Thermal regime of the atmosphere and the earth's surface. Thermal balance of the earth's surface Thermal regime of the underlying surface and atmosphere

Soil is a component of the climate system, which is the most active accumulator of solar heat entering the earth's surface.

The daily course of the underlying surface temperature has one maximum and one minimum. The minimum occurs around sunrise, the maximum occurs in the afternoon. Phase daily course and its daily amplitude depend on the time of year, the state of the underlying surface, the amount and precipitation, as well as, on the location of the stations, the type of soil and its mechanical composition.

According to the mechanical composition, soils are divided into sandy, sandy and loamy, differing in heat capacity, thermal diffusivity and genetic properties (in particular, in color). Dark soils absorb more solar radiation and therefore warm up more than light soils. Sandy and sandy loamy soils, characterized by a smaller, warmer than loamy.

In the annual course of the temperature of the underlying surface, a simple periodicity can be traced with a minimum of winter time and maximum in summer. In most of the territory of Russia, the highest soil temperature is observed in July, on Far East in the coastal strip of the Sea of Okhotsk, on and - in July - August, in the south of Primorsky Krai - in August.

The maximum temperatures of the underlying surface during most of the year characterize the extreme thermal state of the soil, and only for the coldest months - the surface.

The weather conditions favorable for the underlying surface to reach maximum temperatures are: slightly cloudy weather, when the influx of solar radiation is maximum; low wind speeds or calm, since an increase in wind speed increases the evaporation of moisture from the soil; a small amount of precipitation, since dry soil is characterized by lower heat and thermal diffusivity. In addition, in dry soil there is less heat consumption for evaporation. Thus, absolute temperature maxima are usually observed during the clearest sunny days on dry soil and usually in the afternoon.

The geographical distribution of averages from the absolute annual maxima of the underlying surface temperature is similar to the distribution of isogeotherms of the average monthly temperatures of the soil surface in the summer months. Isogeotherms are mainly latitudinal. The influence of the seas on the temperature of the soil surface is manifested in the fact that on the western coast of Japan and, on Sakhalin and Kamchatka, the latitudinal direction of isogeoterms is disturbed and becomes close to meridional (repeats the outlines of the coastline). In the European part of Russia, the values of the average of the absolute annual maxima of the underlying surface temperature vary from 30–35°C on the coast of the northern seas to 60–62°C in the south of the Rostov Region, in the Krasnodar and Stavropol Territories, in the Republic of Kalmykia and the Republic of Dagestan. In the area, the average of the absolute annual maxima of soil surface temperature is 3–5°C lower than in the nearby flat areas, which is associated with the influence of elevations on the increase in precipitation in the area and soil moisture. Plain territories, closed by hills from the prevailing winds, are characterized by a reduced amount of precipitation and lower wind speeds, and, consequently, increased values of extreme temperatures of the soil surface.

The most rapid increase in extreme temperatures from north to south occurs in the zone of transition from the forest and zones to the zone, which is associated with a decrease in precipitation in the steppe zone and with a change in soil composition. In the south, with a generally low level of moisture content in the soil, the same changes in soil moisture correspond to more significant differences in the temperature of soils that differ from each other in mechanical composition.

There is also a sharp decrease in the average of the absolute annual maximums of the temperature of the underlying surface from south to north in the northern regions of the European part of Russia, during the transition from the forest zone to zones and tundra - areas of excessive moisture. The northern regions of the European part of Russia, due to active cyclonic activity, among other things, differ from the southern regions in an increased amount of cloudiness, which sharply reduces the arrival of solar radiation to the earth's surface.

In the Asian part of Russia, the lowest average absolute maxima occur on the islands and in the north (12–19°С). As we move southward, there is an increase in extreme temperatures, and in the north of the European and Asian parts of Russia, this increase occurs more sharply than in the rest of the territory. In areas with a minimum amount of precipitation (for example, the areas between the Lena and Aldan rivers), pockets of increased extreme temperatures are distinguished. Since the areas are very complex, the extreme temperatures of the soil surface for stations located in various forms relief (mountainous regions, basins, lowlands, valleys of large Siberian rivers) are very different. The average values of the absolute annual maxima of the underlying surface temperature reach the highest values in the south of the Asian part of Russia (except for coastal areas). In the south of Primorsky Krai, the average of absolute annual maxima is lower than in continental regions located at the same latitude. Here their values reach 55–59°C.

The minimum temperatures of the underlying surface are also observed under quite specific conditions: on the coldest nights, at hours close to sunrise, during anticyclonic weather conditions, when low cloud cover favors maximum effective radiation.

The distribution of average isogeotherms from the absolute annual minima of the underlying surface temperature is similar to the distribution of isotherms of minimum air temperatures. In most of the territory of Russia, except for the southern and northern regions, the average isogeotherms of the absolute annual minimum temperatures of the underlying surface take on a meridional orientation (decreasing from west to east). In the European part of Russia, the average of the absolute annual minimum temperatures of the underlying surface varies from -25°C in the western and southern regions to -40 ... -45°C in the eastern and, especially, northeastern regions (Timan Ridge and Bolshezemelskaya tundra). The highest mean values of the absolute annual temperature minima (–16…–17°С) take place in Black Sea coast. In most of the Asian part of Russia, the average of the absolute annual minimums vary within -45 ... -55 ° С. Such an insignificant and fairly uniform distribution of temperature over a vast territory is associated with the uniformity of the conditions for the formation of minimum temperatures in areas subject to the influence of the Siberian.

In the districts Eastern Siberia with a complex relief, especially in the Republic of Sakha (Yakutia), along with radiation factors, the relief features have a significant impact on the decrease in minimum temperatures. Here, in the difficult conditions of a mountainous country in depressions and basins, especially favorable conditions are created for cooling the underlying surface. The Republic of Sakha (Yakutia) has the lowest mean values of the absolute annual minimums of the underlying surface temperature in Russia (up to –57…–60°C).

On the coast of the Arctic seas, due to the development of active winter cyclonic activity here, the minimum temperatures are higher than in hinterland. The isogeotherms have an almost latitudinal direction, and the decrease in the average of the absolute annual minima from north to south occurs rather quickly.

On the coast, the isogeotherms repeat the outlines of the shores. The influence of the Aleutian minimum is manifested in the increase in the average of the absolute annual minimums in the coastal zone compared to the inland areas, especially on the southern coast of Primorsky Krai and on Sakhalin. The average of the absolute annual minimums here is –25…–30°C.

The freezing of the soil depends on the magnitude of negative air temperatures in the cold season. The most important factor preventing soil freezing is the presence of snow cover. Its characteristics such as formation time, power, duration of occurrence determine the depth of soil freezing. The late establishment of snow cover contributes to greater freezing of the soil, since in the first half of winter the intensity of soil freezing is greatest and, conversely, the early establishment of snow cover prevents significant freezing of the soil. The influence of the thickness of the snow cover is most pronounced in areas with low air temperatures.

At the same depth of freezing depends on the type of soil, its mechanical composition and humidity.

For example, in the northern regions of Western Siberia, with low and thick snow cover, the depth of soil freezing is less than in more southern and warmer regions with small. A peculiar picture takes place in regions with unstable snow cover (southern regions of the European part of Russia), where it can contribute to an increase in the depth of soil freezing. This is due to the fact that with frequent changes of frost and thaw, an ice crust forms on the surface of a thin snow cover, the thermal conductivity coefficient of which is several times greater than the thermal conductivity of snow and water. The soil in the presence of such a crust cools and freezes much faster. The presence of vegetation cover contributes to a decrease in the depth of soil freezing, as it retains and accumulates snow.

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Temperature regimeunderlying surface

1 . The temperature regime of the underlying surface and activityOlayer

temperature soil instrument

The underlying surface, or active surface, is the surface of the earth (soil, water, snow, etc.) that interacts with the atmosphere in the process of heat and moisture exchange.

An active layer is a layer of soil (including vegetation and snow cover) or water that is involved in heat exchange with environment, and to the depth of which daily and annual temperature fluctuations extend.

The thermal state of the underlying surface has a significant effect on the temperature of the lower layers of air. This influence decreasing with height can be detected even in the upper troposphere.

There are differences in the thermal regime of land and water, which are explained by the difference in their thermophysical properties and heat exchange processes between the surface and underlying layers.

In the soil, short-wave solar radiation penetrates to a depth of tenths of a millimeter, where it is converted into heat. This heat is transferred to the underlying layers by molecular heat conduction.

In water, depending on its transparency, solar radiation penetrates to depths of up to tens of meters, and heat transfer to the deep layers occurs as a result of turbulent mixing, thermal convection, and evaporation.

Turbulence in water bodies is primarily due to waves and currents. At night and in the cold season, thermal convection develops, when water cooled on the surface sinks down due to increased density and is replaced by warmer water from the lower layers. With significant evaporation from the sea surface, the upper layer of water becomes more saline and denser, as a result of which warmer water sinks from the surface to the depths. Therefore, daily temperature fluctuations in water extend to a depth of tens of meters, and in soil - less than a meter. Annual fluctuations in water temperature extend to a depth of hundreds of meters, and in the soil - only 10-20 m; those. in the soil, heat is concentrated in a thin upper layer, which heats up with a positive radiation balance and cools down with a negative one.

Thus, land heats up quickly and cools down quickly, while water heats up slowly and cools down slowly. The large thermal inertia of water bodies is also facilitated by the fact that the specific heat capacity of water is 3-4 times greater than that of soil. For the same reasons, daily and annual temperature fluctuations on the soil surface are much greater than on the water surface.

The daily course of soil surface temperature in clear weather is represented by a wavy curve resembling a sinusoid. At the same time, the temperature minimum is observed shortly after sunrise, when the radiation balance changes sign from "-" to "+". The maximum temperature occurs at 13-14 hours. The smoothness of the daily temperature variation can be disturbed by the presence of clouds, precipitation, and advective changes.

The difference between the maximum and minimum temperatures per day is the daily temperature amplitude.

The amplitude of the daily variation of the soil surface temperature depends on the midday height of the Sun, i.e. on the latitude of the place and time of year. In summer, in clear weather in temperate latitudes, the temperature amplitude of bare soil can reach 55 ° C, and in deserts - 80 ° and more. In cloudy weather, the amplitude is less than in clear weather. Clouds during the day delay direct solar radiation, and at night they reduce the effective radiation of the underlying surface.

Soil temperature is influenced by vegetation and snow cover. Vegetation cover reduces the amplitude of diurnal fluctuations in the temperature of the soil surface, since it prevents its heating by the sun's rays during the day and protects it from radiation cooling at night. At the same time, the average daily temperature of the soil surface also decreases. The snow cover, having low thermal conductivity, protects the soil from intense heat loss, while the daily temperature amplitude sharply decreases compared to bare soil.

The difference between the maximum and minimum average monthly temperatures during the year is called the annual temperature amplitude.

The temperature amplitude of the underlying surface in the annual course depends on latitude (in the tropics - the minimum) and increases with latitude, which is in line with changes in the meridian direction of the annual amplitude of the monthly sums of solar radiation in a solar climate.

The distribution of heat in the soil from the surface to the depth corresponds quite closely to Fourier law. Regardless of the type of soil and its moisture, the period of temperature fluctuations does not change with depth, i.e. at depth, the diurnal variation persists with a period of 24 hours, and in the annual variation, at 12 months. In this case, the amplitude of temperature fluctuations decreases with depth.

At a certain depth (about 70 cm, different depending on the latitude and the season of the year), a layer with a constant daily temperature begins. The amplitude of annual fluctuations decreases almost to zero at a depth of about 30 m in the polar regions, about 15-20 m - in temperate latitudes. The maximum and minimum temperatures, both in the daily and annual variations, occur later than on the surface, and the delay is directly proportional to the depth.

A visual representation of the distribution of soil temperature in depth and in time is given by a graph of thermal isopleths, which is built on the basis of long-term average monthly soil temperatures (Fig. 1.2). Depths are plotted on the vertical axis of the graph, and months are plotted on the horizontal axis. Lines of equal temperatures on a graph are called thermal isopleths.

Moving along the horizontal line allows you to trace the change in temperature at a given depth during the year, and moving along the vertical line gives an idea of the change in temperature with depth for a given month. It can be seen from the graph that the maximum annual temperature amplitude at the surface decreases with depth.

Due to the above differences in the processes of heat transfer between the surface and deep layers of water bodies and land, daily and annual changes in the temperature of the surface of water bodies are much less than those of land. Thus, the daily amplitude of changes in ocean surface temperature is about 0.1-0.2°C in temperate latitudes, and about 0.5°C in the tropics. At the same time, the temperature minimum is observed 2-3 hours after sunrise, and the maximum - about 15-16 hours. The annual amplitude of ocean surface temperature fluctuations is much greater than the daily one. In the tropics, it is about 2-3 ° C, in temperate latitudes about 10 ° C. Daily fluctuations are found at depths of up to 15-20 m, and annual fluctuations - up to 150-400 m.

2 Instruments for measuring the temperature of the active layer

Measurement of soil surface temperature, snow cover and determination of their condition.

The surface of the soil and snow cover is the underlying surface that directly interacts with the atmosphere, absorbs solar and atmospheric radiation and radiates into the atmosphere itself, participates in heat and moisture exchange and affects the thermal regime of the underlying soil layers.

To measure the temperature of the soil and snow cover during the observation period, the mercury meteorological thermometer TM-3 with scale limits from -10 to +85° С; from -25 to +70° С; from -35 to +60° C, with a scale division of 0.5° C. The measurement error at temperatures above -20° C is ±0.5° C, at lower temperatures ± 0.7° C. To determine extreme temperatures between periods are used thermometers maToSimal TM-1 And minimal TM-2(same as for determining the air temperature in the psychrometric booth).

Measurements of soil surface temperature and snow cover are made on an unshaded area 4x6 m in size in the southern part of the meteorological site. In summer, measurements are made on bare, loosened soil, for which the site is dug up in the spring.

Readings on thermometers are taken with an accuracy of 0.1 ° C. The condition of the soil and snow cover is assessed visually. Temperature measurements and monitoring of the underlying surface are carried out throughout the year.

Temperature measurement in the topsoil

To measure the temperature in the upper layer of the soil, termOmercury meteorological cranked meters (Savinova) TM-5(produced as a set of 4 thermometers for measuring soil temperature at depths of 5, 10, 15, 20 cm). Measurement limits: from -10 to +50° С, scale division value 0.5° С, measurement error ±0.5° С. Cylindrical tanks. The thermometers are bent at an angle of 135° in places 2-3 cm from the tank. This allows you to install the thermometers so that the tank and part of the thermometer before bending are in a horizontal position under the soil layer, and part of the thermometer with a scale is located above the soil.

The capillary in the area from the reservoir to the beginning of the scale is covered with a heat-insulating shell, which reduces the effect on the thermometer readings of the soil layer lying above its reservoir, provides a more accurate temperature measurement at the depth where the reservoir is located.

Observations using Savinov's thermometers are carried out on the same site where thermometers are installed to measure the temperature of the soil surface, at the same time and only in the warm part of the year. When the temperature drops at a depth of 5 cm below 0 ° C, thermometers are dug out, installed in the spring after the snow cover has melted.

Measurement of soil and soil temperature at depths under natural cover

Used to measure soil temperature thermometer mercury meteorological soil-deep TM-10. Its length is 360 mm, diameter is 16 mm, the upper limit of the scale is from + 31 to +41 ° C, and the lower limit is from -10 to -20 ° C. The scale division is 0.2 ° C, the measurement error at positive temperatures is ±0, 2 ° С, at negative ± 0.3 ° С.

The thermometer is placed in a vinyl plastic frame, ending at the bottom with a copper or brass cap filled with copper filings around the thermometer reservoir. A wooden rod is attached to the upper end of the frame, with the help of which the thermometer is immersed in an ebonite pipe located in the ground at the depth of measuring the soil temperature.

Measurements are made on a 6x8 m area with natural vegetation in the southeastern part of the meteorological site. Exhaust soil-depth thermometers are installed along the east-west line at a distance of 50 cm from each other at depths of 0.2; 0.4; 0.8; 1.2; 1.6; 2.4; 3.2 m in ascending order of depth.

With a snow cover of up to 50 cm, the part of the pipe protruding above the ground is 40 cm, with higher altitude snow cover - 100 cm. The installation of external (ebonite) pipes is carried out using a drill in order to less disturb the natural state of the soil.

Exhaust thermometer observations are made all year round, daily at depths of 0.2 and 0.4 m - all 8 periods (except for the period when the snow height exceeds 15 cm), at other depths - 1 time per day.

Surface water temperature measurement

For measurement, a mercury thermometer with a division value of 0.2 ° C, with scale limits from -5 to + 35 ° C is used. The thermometer is placed in a frame, which is designed to save the thermometer readings after it has been raised from the water, as well as to protect against mechanical damage . The frame consists of a glass and two tubes: outer and inner.

The thermometer in the frame is placed so that its scale is located against the slots in the tubes, and the thermometer reservoir is in the middle part of the glass. The frame has a shackle for attaching to the cable. When the thermometer is immersed, the slot is closed by turning the outer cover, and after lifting and for taking a reading, it is opened. The holding time of the thermometer at the point is 5-8 minutes, the penetration into the water is no more than 0.5 m.

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transcript

1 THERMAL REGIME OF THE ATMOSPHERE AND THE EARTH'S SURFACE

2 Heat balance of the earth's surface The total radiation and the counter radiation of the atmosphere enter the earth's surface. They are absorbed by the surface, that is, they go to heat the upper layers of soil and water. At the same time, the earth's surface itself radiates and loses heat in the process.

3 Earth surface (active surface, underlying surface) i.e. the surface of soil or water (vegetation, snow, ice cover), continuously different ways gains and loses heat. Through the earth's surface, heat is transferred up into the atmosphere and down into the soil or water. In any period of time, the same amount of heat goes up and down from the earth's surface as it receives from above and below during this time. If it were otherwise, the law of conservation of energy would not be fulfilled: it would be necessary to assume that energy arises or disappears on the earth's surface. The algebraic sum of all heat inputs and outputs on the earth's surface should be equal to zero. This is expressed by the equation of the heat balance of the earth's surface.

4 heat balance equation To write the heat balance equation, firstly, we combine the absorbed radiation Q (1- A) and the effective radiation Eef = Ez - Ea into a radiation balance: B=S +D R + Ea Ez or B= Q (1 - A) - Eef

5 Radiation balance of the earth's surface - This is the difference between absorbed radiation (total radiation minus reflected) and effective radiation (radiation of the earth's surface minus counterradiation) B=S +D R + Ea Ez B=Q(1-A)-Eef 0 Therefore V= - Eeff

6 1) The arrival of heat from the air or its release into the air by thermal conductivity, we denote P 2) The same income or consumption by heat exchange with deeper layers of soil or water, we will call A. 3) The loss of heat during evaporation or its arrival during condensation on the earth's surface, we denote LE where L is the specific heat of vaporization and E is evaporation/condensation (mass of water). Then the equation of the heat balance of the earth's surface will be written as follows: B \u003d P + A + LE The heat balance equation refers to the unit area of the active surface All its members are energy flows They have the dimension of W / m 2

7, the meaning of the equation is that the radiative balance on the earth's surface is balanced by non-radiative heat transfer. The equation is valid for any period of time, including for many years.

8 Components of the heat balance of the Earth-atmosphere system Received from the sun Released by the earth's surface

9 Heat balance options Q Radiation balance LE Evaporation heat loss H Turbulent heat flux from (into) the atmosphere from the underlying surface G -- Heat flux into (from) the depth of the soil

10 Arrival and consumption B=Q(1-A)-Eef B= P+A+LE Q(1-A)- The solar radiation flux, partially reflected, penetrates deep into the active layer to different depths and always heats it Effective radiation usually cools the surface Eeff Evaporation also always cools the surface LE The heat flux into the atmosphere Р cools the surface during the day when it is hotter than the air, but warms it at night when the atmosphere is warmer than the earth's surface. Heat flow into the soil A, removes excess heat during the day (cools the surface), but brings the missing heat from the depths at night

11 The average annual temperature of the earth's surface and the active layer varies little from year to year From day to day and from year to year, the average temperature of the active layer and the earth's surface in any place varies little. This means that during the day, almost as much heat enters the depths of the soil or water during the day as it leaves it at night. But still, during the summer days, the heat goes down a little more than it comes from below. Therefore, the layers of soil and water, and their surface, are heated day by day. Happens in winter reverse process. These seasonal changes in the heat input and output in soil and water are almost balanced over the year, and the average annual temperature of the earth's surface and the active layer varies little from year to year.

12 The underlying surface is the earth's surface that interacts directly with the atmosphere.

13 Active surface Types of heat transfer of the active surface This is the surface of soil, vegetation and any other type of land and ocean surface (water), which absorbs and gives off heat. It regulates the thermal regime of the body itself and the adjacent air layer (surface layer)

14 Approximate values of the parameters of the thermal properties of the active layer of the Earth Substance Density Kg / m 3 Heat capacity J / (kg K) Thermal conductivity W / (m K) air 1.02 water, 63 ice, 5 snow, 11 wood, 0 sand, 25 rock, 0

15 How the earth warms up: thermal conductivity is one of the types of heat transfer

16 Mechanism of heat conduction (transfer of heat deep into bodies) Heat conduction is one of the types of heat transfer from more heated parts of the body to less heated ones, leading to temperature equalization. At the same time, energy is transferred in the body from particles (molecules, atoms, electrons) with higher energy to particles with lower energy. flow q is proportional to grad T, that is, where λ is the thermal conductivity coefficient, or simply thermal conductivity, does not depend on grad T. λ depends on the aggregate state of the substance (see table), its atomic and molecular structure, temperature and pressure, composition (in the case mixture or solution), etc. Heat flux into the soil In the heat balance equation, this is A G T c z

17 The transfer of heat to the soil obeys the laws of Fourier thermal conductivity (1 and 2) 1) The period of temperature fluctuation does not change with depth 2) The amplitude of fluctuation decays exponentially with depth

18 The spread of heat into the soil The greater the density and moisture of the soil, the better it conducts heat, the faster it spreads to the depth and the deeper the temperature fluctuations penetrate. But, regardless of the type of soil, the period of temperature fluctuations does not change with depth. This means that not only on the surface, but also at depths, there remains a daily course with a period of 24 hours between each two successive maximums or minimums, and an annual course with a period of 12 months.

19 Formation of temperature in the upper soil layer (What cranked thermometers show) The amplitude of fluctuations decreases exponentially. Below a certain depth (about cm cm), the temperature hardly changes during the day.

20 Daily and annual variation of soil surface temperature The temperature on the soil surface has a daily variation: The minimum is observed approximately half an hour after sunrise. By this time, the radiation balance of the soil surface becomes equal to zero; the heat transfer from the upper soil layer by effective radiation is balanced by the increased influx of total radiation. The non-radiative heat exchange at this time is negligible. Then the temperature on the soil surface rises up to hours, when it reaches a maximum in the daily course. After that, the temperature starts to drop. The radiation balance in the afternoon remains positive; however, during the daytime heat is released from the upper soil layer to the atmosphere not only through effective radiation, but also through increased thermal conductivity, as well as increased evaporation of water. The transfer of heat into the depth of the soil also continues. Therefore, the temperature on the soil surface drops from the hours to the morning low.

21 Daily variation of temperature in the soil at different depths, the amplitudes of fluctuations decrease with depth. So, if on the surface the daily amplitude is 30, and at a depth of 20 cm - 5, then at a depth of 40 cm it will already be less than 1. At some relatively shallow depth, the daily amplitude decreases to zero. At this depth (about cm), a layer of constant daily temperature begins. Pavlovsk, May. The amplitude of annual temperature fluctuations decreases with depth according to the same law. However, annual fluctuations propagate to a greater depth, which is quite understandable: there is more time for their propagation. The amplitudes of annual fluctuations decrease to zero at a depth of about 30 m in the polar latitudes, about 10 m in the middle latitudes, and about 10 m in the tropics (where the annual amplitudes are also lower on the soil surface than in the middle latitudes). At these depths begins, a layer of constant annual temperature. The diurnal cycle in the soil attenuates with depth in amplitude and lags in phase depending on soil moisture: the maximum occurs in the evening on land and at night on the water (the same is true for the minimum in the morning and afternoon)

22 Fourier heat conduction laws (3) 3) The oscillation phase delay increases linearly with depth. the time of the onset of the temperature maximum shifts relative to the higher layers by several hours (towards evening and even night)

23 The fourth Fourier law The depths of the layers of constant daily and annual temperature are related to each other as the square roots of the periods of oscillations, i.e. as 1: 365. This means that the depth at which the annual oscillations decay is 19 times greater than the depth where the diurnal fluctuations are damped. And this law, like the rest of Fourier's laws, is quite well confirmed by observations.

24 Formation of temperature in the entire active layer of the soil (What is shown by exhaust thermometers) 1. The period of temperature fluctuations does not change with depth 2. Below a certain depth, the temperature does not change over the year. 3. Depths of propagation of annual fluctuations are approximately 19 times greater than daily fluctuations

25 Penetration of temperature fluctuations deep into the soil in accordance with the thermal conductivity model

26 . The average daily temperature variation on the soil surface (P) and in the air at a height of 2 m (V). Pavlovsk, June. The maximum temperatures on the soil surface are usually higher than in the air at the height of the meteorological booth. This is understandable: during the day, solar radiation primarily heats the soil, and already the air heats up from it.

27 annual course of soil temperature The temperature of the soil surface, of course, also changes in the annual course. IN tropical latitudes its annual amplitude, i.e., the difference between the long-term average temperatures of the warmest and coldest months of the year, is small and increases with latitude. In the northern hemisphere at latitude 10 it is about 3, at latitude 30 about 10, at latitude 50 it averages about 25.

28 Temperature fluctuations in the soil attenuate with depth in amplitude and lag in phase, the maximum shifts to autumn, and the minimum to spring Annual maxima and minima are delayed by days for each meter of depth. Annual variation of temperature in the soil at different depths from 3 to 753 cm in Kaliningrad. In tropical latitudes, the annual amplitude, i.e., the difference in long-term average temperatures of the warmest and coldest months of the year, is small and increases with latitude. In the northern hemisphere at latitude 10 it is about 3, at latitude 30 about 10, at latitude 50 it averages about 25.

29 Thermal isopleth method Visually represents all the features of temperature variation both in time and with depth (in one point) Example of annual variation and daily variation Isoplets of annual temperature variation in soil in Tbilisi

30 Daily course of air temperature of the surface layer The air temperature changes in the daily course following the temperature of the earth's surface. Since the air is heated and cooled from the earth's surface, the amplitude of the daily temperature variation in the meteorological booth is less than on the soil surface, on average by about one third. The rise in air temperature begins with the rise in soil temperature (15 minutes later) in the morning, after sunrise. In hours, the temperature of the soil, as we know, begins to drop. In hours it equalizes with the air temperature; from that time on, with a further drop in soil temperature, the air temperature also begins to fall. Thus, the minimum in the daily course of air temperature near the earth's surface falls on the time shortly after sunrise, and the maximum at hours.

32 Differences in the thermal regime of soil and water bodies There are sharp differences in the heating and thermal characteristics of the surface layers of soil and the upper layers of water bodies. In soil, heat is distributed vertically by molecular heat conduction, and in lightly moving water also by turbulent mixing of water layers, which is much more efficient. Turbulence in water bodies is primarily due to waves and currents. But at night and in the cold season, thermal convection also joins this kind of turbulence: water cooled on the surface sinks down due to increased density and is replaced by warmer water from the lower layers.

33 Temperature features of water bodies associated with large turbulent heat transfer coefficients Daily and annual fluctuations in water penetrate to much greater depths than in soil Temperature amplitudes are much smaller and almost the same in the UML of lakes and seas Heat fluxes in the active water layer are many times greater than in soil

34 Daily and annual fluctuations As a result, daily fluctuations in water temperature extend to a depth of about tens of meters, and in the soil to less than one meter. Annual fluctuations in temperature in water extend to a depth of hundreds of meters, and in soil only to m. So, the heat that comes to the surface of the water during the day and summer penetrates to a considerable depth and heats up a large thickness of water. The temperature of the upper layer and the surface of the water itself rises little at the same time. in the soil incoming warmth distributed in a thin upper layer, which is thus strongly heated. Heat exchange with deeper layers in the heat balance equation "A" for water is much greater than for soil, and the heat flux into the atmosphere "P" (turbulence) is correspondingly less. At night and in winter, water loses heat from the surface layer, but instead of it comes the accumulated heat from the underlying layers. Therefore, the temperature at the surface of the water decreases slowly. On the soil surface, the temperature drops rapidly during heat release: the heat accumulated in the thin upper layer quickly leaves it without being replenished from below.

35 Maps of turbulent heat transfer of the atmosphere and the underlying surface were obtained

36 In the oceans and seas, evaporation also plays a role in the mixing of layers and the associated heat transfer. With significant evaporation from the sea surface, the upper layer of water becomes more salty and dense, as a result of which the water sinks from the surface to the depths. In addition, radiation penetrates deeper into water compared to soil. Finally, the heat capacity of water is large in comparison with soil, and the same amount of heat heats a mass of water to a lower temperature than the same mass of soil. HEAT CAPACITY - The amount of heat absorbed by the body when heated by 1 degree (Celsius) or given off when cooled by 1 degree (Celsius) or the ability of the material to accumulate thermal energy.

37 Due to these differences in the distribution of heat: 1. during the warm season, water accumulates a large amount of heat in a sufficiently thick layer of water, which is released into the atmosphere during the cold season. 2. during the warm season, the soil gives off at night most of the heat that it receives during the day, and accumulates little of it by winter. As a result of these differences, the air temperature over the sea is lower in summer and higher in winter than over land. In the middle latitudes, during the warm half of the year, 1.5-3 kcal of heat is accumulated in the soil per square centimeter of surface. In cold weather, the soil gives off this heat to the atmosphere. The value of ±1.5 3 kcal / cm 2 per year is the annual heat cycle of the soil.

38 The amplitudes of the annual temperature variation determine the continental climate or nautical map amplitudes of the annual temperature variation near the Earth's surface

39 The position of the place relative to the coastline significantly affects the regime of temperature, humidity, cloudiness, precipitation and determines the degree of continentality of the climate.

40 Climate continentality Climate continentality is a set of characteristic features of the climate, determined by the influence of the continent on the processes of climate formation. In a climate over the sea (marine climate), small annual air temperature amplitudes are observed in comparison with the continental climate over land with large annual temperature amplitudes.

41 The annual variation of air temperature at latitude 62 N: in the Faroe Islands and Yakutsk reflects the geographical position of these points: in the first case - near the western coast of Europe, in the second - in the eastern part of Asia

42 Average annual amplitude in Torshavn 8, in Yakutsk 62 C. On the continent of Eurasia, an increase in the annual amplitude in the direction from west to east is observed.

43 Eurasia - the continent with the greatest distribution of continental climate This type of climate is typical for the inner regions of the continents. The continental climate is dominant in a significant part of the territory of Russia, Ukraine, Central Asia(Kazakhstan, Uzbekistan, Tajikistan), Inner China, Mongolia, inner regions of the USA and Canada. The continental climate leads to the formation of steppes and deserts, since most of the moisture of the seas and oceans does not reach the inland regions.

44 continentality index is a numerical characteristic of climate continentality. There are a number of options for I K, which are based on one or another function of the annual amplitude of air temperature A: according to Gorchinsky, according to Konrad, according to Zenker, according to Khromov. There are indices built on other grounds. For example, it is proposed as an I.K. the ratio of the frequency of occurrence of continental air masses to the frequency of sea air masses. L. G. Polozova proposed to characterize the continentality separately for January and July in relation to the greatest continentality at a given latitude; this latter is determined from temperature anomalies. Η. Η. Ivanov proposed I.K. as a function of latitude, annual and daily temperature amplitudes, and humidity deficit in the driest month.

45 continentality index The magnitude of the annual amplitude of air temperature depends on the geographical latitude. At low latitudes, the annual temperature amplitudes are smaller compared to high latitudes. This provision leads to the need to exclude the influence of latitude on the annual amplitude. For this, various indicators of climate continentality are proposed, represented as a function of the annual temperature amplitude and latitude. Formula L. Gorchinsky where A is the annual temperature amplitude. The average continentality over the ocean is zero, and for Verkhoyansk it is 100.

47 Maritime and continental Temperate maritime climate characterized quite warm winter(from -8 C to 0 C), cool summer (+16 C) and a large amount of precipitation (more than 800 mm), which falls evenly throughout the year. The temperate continental climate is characterized by fluctuations in air temperature from about -8 C in January to +18 C in July, precipitation here is more than mm, which falls mostly in summer. The area of continental climate is characterized by more low temperatures in winter (up to -20 C) and less precipitation (about 600 mm). In the temperate sharply continental climate, winter will be even colder down to -40 C, and precipitation will be even less than mm.

48 Extremes Temperatures up to +55, and even up to +80 in deserts are observed in summer on the surface of bare soil in the Moscow region. Night temperature minima, on the contrary, are lower on the soil surface than in the air, since, first of all, the soil is cooled by effective radiation, and the air is already cooled from it. In winter in the Moscow region, nighttime temperatures on the surface (covered with snow at this time) can drop below 50, in summer (except July) to zero. On the snowy surface in the interior of Antarctica, even the average monthly temperature in June is about 70, and in some cases it can drop to 90.

49 Maps of average Air temperature January and July

50 Distribution of air temperature (zonality of distribution is the main factor of climatic zonality) Average annual Average summer(July) Average for January Average for latitudinal zones

51 Temperature regime of the territory of Russia It is characterized by great contrasts in winter. In Eastern Siberia, a winter anticyclone, which is an extremely stable baric formation, contributes to the formation of a cold pole in northeastern Russia with an average monthly air temperature in winter of 42 C. The average minimum temperature in winter is 55 C. in winter it changes from C in the southwest, reaching positive values on the Black Sea coast, to C in the central regions.

52 Average surface air temperature (С) in winter

53 Average surface air temperature (С) in summer The average air temperature varies from 4 5 C on the northern coasts to C in the southwest, where its average maximum is C and the absolute maximum is 45 C. The amplitude of extreme temperatures reaches 90 C. A feature of the air temperature regime in Russia is its large daily and annual amplitudes, especially in the sharply continental climate of the Asian territory. The annual amplitude varies from 8 10 C ETR to 63 C in Eastern Siberia in the region of the Verkhoyansk Range.

54 Effect of vegetation cover on soil surface temperature Vegetation cover reduces soil cooling at night. In this case, night radiation occurs mainly from the surface of the vegetation itself, which will be the most cooled. The soil under vegetation maintains a higher temperature. However, during the day, vegetation prevents the radiative heating of the soil. The daily temperature range under vegetation is reduced, and the average daily temperature is lowered. So, vegetation cover generally cools the soil. In the Leningrad region, the surface of the soil under field crops can be 15 degrees colder during the daytime than the soil under fallow. On average, per day it is colder than bare soil by 6, and even at a depth of 5-10 cm there is a difference of 3-4.

55 Effect of snow cover on soil temperature Snow cover protects the soil from heat loss in winter. The radiation comes from the surface of the snow cover itself, and the soil underneath remains warmer than the bare soil. At the same time, the daily temperature amplitude on the soil surface under snow sharply decreases. In the middle zone of the European territory of Russia, with a snow cover of 50 cm, the temperature of the soil surface under it is 6-7 higher than the temperature of the bare soil, and 10 higher than the temperature on the surface of the snow cover itself. Winter soil freezing under snow reaches depths of about 40 cm, and without snow it can spread to depths of more than 100 cm. Thus, vegetation cover in summer reduces the temperature on the soil surface, and snow cover in winter, on the contrary, increases it. The combined effect of vegetation cover in summer and snow cover in winter reduces the annual temperature amplitude on the soil surface; this is a decrease of the order of 10 compared to bare soil.

56 HAZARDOUS METEOROLOGICAL PHENOMENA AND THEIR CRITERIA 1. very strong wind (including squalls) of at least 25 m/s, (including gusts), on sea coasts and in mountainous areas of at least 35 m/s; 2. very heavy rain of at least 50 mm for a period of not more than 12 hours 3. heavy rain of at least 30 mm for a period of not more than 1 hour; 4. very heavy snow of at least 20 mm for a period of no more than 12 hours; 5. large hail - not less than 20mm; 6. heavy snowstorm - with an average wind speed of at least 15 m/s and visibility of less than 500 m;

57 7. Severe dust storm with an average wind speed of at least 15 m/s and visibility of no more than 500 m; 8. Heavy fog visibility no more than 50m; 9. Severe ice-frost deposits of at least 20 mm for ice, at least 35 mm for complex deposits or wet snow, at least 50 mm for hoarfrost. 10. Extreme heat - High maximum air temperature of at least 35 ºС for more than 5 days. 11. Severe frost - The minimum air temperature is not less than minus 35ºС for at least 5 days.

58 High temperature hazards Fire hazard Extreme heat

59 Low temperature hazards

60 Freeze. Freezing is a short-term decrease in air temperature or an active surface (soil surface) to 0 C and below against a general background of positive average daily temperatures.

61 Basic concepts of air temperature WHAT YOU NEED TO KNOW! Map of average annual temperature Differences in summer and winter temperatures Zonal distribution of temperature Influence of distribution of land and sea Altitude distribution of air temperature Daily and annual variation of soil and air temperature Hazardous weather phenomena due to temperature regime

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The surface directly heated by the sun's rays and giving off heat to the underlying layers and air is called active. The temperature of the active surface, its value and change (daily and annual variation) are determined by the heat balance.

The maximum value of almost all components of the heat balance is observed in the near noon hours. The exception is the maximum heat exchange in the soil, which falls on the morning hours.

The maximum amplitudes of the diurnal variation of the heat balance components are observed in summer, the minimum - in winter. In the diurnal course of surface temperature, dry and devoid of vegetation, on a clear day, the maximum occurs after 13:00, and the minimum occurs around the time of sunrise. Cloudiness disrupts the regular course of surface temperature and causes a shift in the moments of maxima and minima. Big influence surface temperature is influenced by its humidity and vegetation cover. Daytime surface temperature maxima can be + 80°C or more. Daily fluctuations reach 40°. Their value depends on the latitude of the place, time of year, cloudiness, thermal properties of the surface, its color, roughness, vegetation cover, and slope exposure.

The annual course of the temperature of the active layer is different at different latitudes. The maximum temperature in middle and high latitudes is usually observed in June, the minimum - in January. The amplitudes of annual fluctuations in the temperature of the active layer at low latitudes are very small; at middle latitudes on land, they reach 30°. The annual fluctuations in surface temperature in temperate and high latitudes are strongly influenced by snow cover.

It takes time to transfer heat from layer to layer, and the moments of the onset of maximum and minimum temperatures during the day are delayed by every 10 cm by about 3 hours. If the highest temperature on the surface was at about 13:00, at a depth of 10 cm the maximum temperature will come at about 16:00, and at a depth of 20 cm - at about 19:00, etc. With successive heating of the underlying layers from the overlying ones, each layer absorbs a certain amount of heat. The deeper the layer, the less heat it receives and the weaker the temperature fluctuations in it. The amplitude of daily temperature fluctuations with depth decreases by 2 times for every 15 cm. This means that if on the surface the amplitude is 16°, then at a depth of 15 cm it is 8°, and at a depth of 30 cm it is 4°.

At an average depth of about 1 m, the daily fluctuations in soil temperature "fade out". The layer in which these oscillations practically stop is called the layer constant daily temperature.

The longer the period of temperature fluctuations, the deeper they spread. In the middle latitudes, the layer of constant annual temperature is located at a depth of 19-20 m, in high latitudes at a depth of 25 m. In tropical latitudes, the annual temperature amplitudes are small and the layer of constant annual amplitude is located at a depth of only 5-10 m. and minimum temperatures are delayed by an average of 20-30 days per meter. Thus, if the lowest temperature on the surface was observed in January, at a depth of 2 m it occurs in early March. Observations show that the temperature in the layer of constant annual temperature is close to the average annual air temperature above the surface.

Water, having a higher heat capacity and lower thermal conductivity than land, heats up more slowly and releases heat more slowly. Part sun rays falling on the water surface is absorbed by the uppermost layer, and some of them penetrate to a considerable depth, directly heating some of its layer.

The mobility of water makes heat transfer possible. Due to turbulent mixing, heat transfer in depth occurs 1000 - 10,000 times faster than through heat conduction. When the surface layers of water cool, thermal convection occurs, accompanied by mixing. Daily temperature fluctuations on the surface of the Ocean in high latitudes are on average only 0.1°, in temperate latitudes - 0.4°, in tropical latitudes - 0.5°. The penetration depth of these vibrations is 15-20m. The annual temperature amplitudes on the surface of the Ocean range from 1° in equatorial latitudes to 10.2° in temperate latitudes. Annual temperature fluctuations penetrate to a depth of 200-300 m. The moments of maximum temperature in water bodies are late compared to land. The maximum occurs at about 15-16 hours, the minimum - 2-3 hours after sunrise.

Thermal regime of the lower layer of the atmosphere.

The air is heated mainly not by the sun's rays directly, but due to the transfer of heat to it by the underlying surface (the processes of radiation and heat conduction). The most important role in the transfer of heat from the surface to the overlying layers of the troposphere is played by heat exchange and transfer of latent heat of vaporization. The random movement of air particles caused by its heating of an unevenly heated underlying surface is called thermal turbulence or thermal convection.

If instead of small chaotic moving vortices, powerful ascending (thermals) and less powerful descending air movements begin to predominate, convection is called orderly. Air warming near the surface rushes upward, transferring heat. Thermal convection can only develop as long as the air has a temperature higher than the temperature of the environment in which it rises (an unstable state of the atmosphere). If the temperature of the rising air is equal to the temperature its environment, the uplift will stop (indifferent state of the atmosphere); if the air becomes colder than the environment, it will begin to sink (the steady state of the atmosphere).

With the turbulent movement of air, more and more of its particles, in contact with the surface, receive heat, and rising and mixing, give it to other particles. The amount of heat received by air from the surface through turbulence is 400 times greater than the amount of heat it receives as a result of radiation, and as a result of transfer by molecular heat conduction - almost 500,000 times. Heat is transferred from the surface to the atmosphere along with the moisture evaporated from it, and then released during the condensation process. Each gram of water vapor contains 600 calories of latent heat of vaporization.

In rising air, the temperature changes due to adiabatic process, i.e., without heat exchange with the environment, due to the conversion of the internal energy of the gas into work and work into internal energy. Since the internal energy is proportional absolute temperature gas, the temperature changes. The rising air expands, performs work for which it expends internal energy, and its temperature decreases. The descending air, on the contrary, is compressed, the energy spent on expansion is released, and the air temperature rises.

The amount of cooling of saturated air when it rises by 100 m depends on the air temperature and atmospheric pressure and varies within wide limits. Unsaturated air, descending, heats up by 1 ° per 100 m, saturated by a smaller amount, since evaporation takes place in it, for which heat is expended. Rising saturated air usually loses moisture during precipitation and becomes unsaturated. When lowered, such air heats up by 1 ° per 100 m.

As a result, the decrease in temperature during ascent is less than its increase during lowering, and the air that rises and then descends at the same level at the same pressure will have a different temperature - the final temperature will be higher than the initial one. Such a process is called pseudoadiabatic.

Since the air is heated mainly from the active surface, the temperature in the lower atmosphere, as a rule, decreases with height. The vertical gradient for the troposphere averages 0.6° per 100 m. It is considered positive if the temperature decreases with height, and negative if it rises. In the lower surface layer of air (1.5-2 m), vertical gradients can be very large.

The increase in temperature with height is called inversion, and a layer of air in which the temperature increases with height, - inversion layer. In the atmosphere, layers of inversion can almost always be observed. At the earth's surface, when it is strongly cooled, as a result of radiation, radiative inversion(radiation inversion) . It appears on clear summer nights and can cover a layer of several hundred meters. In winter, in clear weather, the inversion persists for several days and even weeks. Winter inversions can cover a layer up to 1.5 km.

The inversion is enhanced by the relief conditions: cold air flows into the depression and stagnates there. Such inversions are called orographic. Powerful inversions called adventitious, are formed in those cases when relatively warm air comes to a cold surface, cooling its lower layers. Daytime advective inversions are weakly expressed; at night they are enhanced by radiative cooling. In spring, the formation of such inversions is facilitated by the snow cover that has not yet melted.

Frosts are associated with the phenomenon of temperature inversion in the surface air layer. Freeze - a decrease in air temperature at night to 0 ° and below at a time when the average daily temperatures are above 0 ° (autumn, spring). It may also be that frosts are observed only on the soil when the air temperature above it is above zero.

The thermal state of the atmosphere affects the propagation of light in it. In cases where the temperature changes sharply with height (increases or decreases), there are mirages.

Mirage - an imaginary image of an object that appears above it (upper mirage) or below it (lower mirage). Less common are lateral mirages (the image appears from the side). The cause of mirages is the curvature of the trajectory of light rays coming from an object to the observer's eye, as a result of their refraction at the boundary of layers with different densities.

The daily and annual temperature variation in the lower troposphere up to a height of 2 km generally reflects the surface temperature variation. With distance from the surface, the amplitudes of temperature fluctuations decrease, and the moments of maximum and minimum are delayed. Daily fluctuations in air temperature in winter are noticeable up to a height of 0.5 km, in summer - up to 2 km.

The amplitude of diurnal temperature fluctuations decreases with increasing latitude. The largest daily amplitude is in subtropical latitudes, the smallest - in polar ones. In temperate latitudes, diurnal amplitudes are different in different times of the year. In high latitudes, the largest daily amplitude is in spring and autumn, in temperate latitudes - in summer.

The annual course of air temperature depends primarily on the latitude of the place. From the equator to the poles, the annual amplitude of air temperature fluctuations increases.

There are four types of annual temperature variation according to the magnitude of the amplitude and the time of the onset of extreme temperatures.

equatorial type characterized by two maxima (after the equinoxes) and two minima (after the solstices). The amplitude over the Ocean is about 1°, over land - up to 10°. The temperature is positive throughout the year.

Tropical type - one maximum (after the summer solstice) and one minimum (after the winter solstice). The amplitude over the Ocean is about 5°, on land - up to 20°. The temperature is positive throughout the year.

Moderate type - one maximum (in the northern hemisphere over land in July, over the Ocean in August) and one minimum (in the northern hemisphere over land in January, over the Ocean in February). Four seasons are clearly distinguished: warm, cold and two transitional. The annual temperature amplitude increases with increasing latitude, as well as with distance from the Ocean: on the coast 10°, away from the Ocean - up to 60° and more (in Yakutsk - -62.5°). The temperature during the cold season is negative.

polar type - winter is very long and cold, summer is short and cool. Annual amplitudes are 25° and more (over land up to 65°). The temperature is negative most of the year. The overall picture of the annual course of air temperature is complicated by the influence of factors, among which the underlying surface is of particular importance. Over the water surface, the annual temperature variation is smoothed out; over land, on the contrary, it is more pronounced. Snow and ice cover greatly reduces annual temperatures. The height of the place above the level of the Ocean, relief, distance from the Ocean, and cloudiness also affect. The smooth course of the annual air temperature is disturbed by disturbances caused by the intrusion of cold or, conversely, warm air. An example can be spring returns of cold weather (cold waves), autumn returns of heat, winter thaws in temperate latitudes.

Distribution of air temperature at the underlying surface.

If the earth's surface were homogeneous, and the atmosphere and hydrosphere were stationary, the distribution of heat over the Earth's surface would be determined only by the influx of solar radiation, and the air temperature would gradually decrease from the equator to the poles, remaining the same at each parallel (solar temperatures). Indeed, the average annual air temperatures are determined by the heat balance and depend on the nature of the underlying surface and the continuous interlatitudinal heat exchange carried out through the movement of air and waters of the Ocean, and therefore differ significantly from solar temperatures.

The actual average annual air temperatures near the earth's surface in low latitudes are lower, and in high latitudes, on the contrary, they are higher than solar ones. In the southern hemisphere, the actual average annual temperatures at all latitudes are lower than in the northern. The average air temperature near the earth's surface in the northern hemisphere in January is +8°C, in July +22°C; in the south - +10° C in July, +17° C in January. The average air temperature for the year at the earth's surface is +14 ° C as a whole.

If we mark the highest average annual or monthly temperatures on different meridians and connect them, we get a line thermal maximum, often called the thermal equator. It is probably more correct to consider the parallel (latitudinal circle) with the highest normal average temperatures of the year or any month as the thermal equator. The thermal equator does not coincide with the geographic one and is "shifted"; to North. During the year it moves from 20° N. sh. (in July) to 0° (in January). There are several reasons for the shift of the thermal equator to the north: the predominance of land in the tropical latitudes of the northern hemisphere, the Antarctic cold pole, and, perhaps, the duration of summer matters (summer in the southern hemisphere is shorter).

Thermal belts.

Isotherms are taken beyond the boundaries of thermal (temperature) belts. There are seven thermal zones:

hot belt, located between the annual isotherm + 20 ° of the northern and southern hemispheres; two temperate zones, bounded from the side of the equator by the annual isotherm + 20 °, from the poles by the isotherm + 10 ° of the warmest month;

two cold belts, located between the isotherm + 10 ° and and the warmest month;

two frost belts located near the poles and bounded by the 0° isotherm of the warmest month. In the northern hemisphere this is Greenland and the space near the north pole, in the southern hemisphere - the area inside the parallel of 60 ° S. sh.

Temperature zones are the basis of climatic zones. Within each belt, large variations in temperature are observed depending on the underlying surface. On land, the influence of relief on temperature is very great. The change in temperature with height for every 100 m is not the same in different temperature zones. The vertical gradient in the lower kilometer layer of the troposphere varies from 0° over the ice surface of Antarctica to 0.8° in summer over tropical deserts. Therefore, the method of bringing temperatures to sea level using an average gradient (6°/100 m) can sometimes lead to gross errors. The change in temperature with height is the cause of vertical climatic zonality.

WATER IN THE ATMOSPHERE

The earth's atmosphere contains about 14,000 km 3 of water vapor. Water enters the atmosphere mainly as a result of evaporation from the Earth's surface. Moisture condenses in the atmosphere, is carried by air currents and falls back to the earth's surface. There is a constant cycle of water, possible due to its ability to be in three states (solid, liquid and vapor) and easily move from one state to another.

Characteristics of air humidity.

Absolute humidity - the content of water vapor in the atmosphere in grams per 1 m 3 of air ("; a";).

Relative humidity - the ratio of the actual water vapor pressure to saturation elasticity, expressed as a percentage. Relative humidity characterizes the degree of saturation of air with water vapor.

Humidity deficiency- lack of saturation at a given temperature:

Dew point - the temperature at which water vapor in the air saturates it.

Evaporation and evaporation. Water vapor enters the atmosphere through evaporation from the underlying surface (physical evaporation) and transpiration. The process of physical evaporation consists in overcoming cohesive forces by rapidly moving water molecules, in separating them from the surface and passing into the atmosphere. The higher the temperature of the evaporating surface, the faster the movement of molecules and the more of them enters the atmosphere.

When the air is saturated with water vapor, the evaporation process stops.

The evaporation process requires heat: the evaporation of 1 g of water requires 597 cal, the evaporation of 1 g of ice requires 80 cal more. As a result, the temperature of the evaporating surface decreases.

Evaporation from the ocean at all latitudes is much greater than evaporation from land. Its maximum value for the Ocean reaches 3000 cm per year. In tropical latitudes, the annual amounts of evaporation from the surface of the Ocean are the largest and it changes little during the year. In temperate latitudes, the maximum evaporation from the Ocean is in winter, in polar latitudes - in summer. The maximum evaporation from the land surface is 1000 mm. Its differences in latitudes are determined by the radiation balance and moisture. In general, in the direction from the equator to the poles, in accordance with the decrease in temperature, evaporation decreases.

In the absence of a sufficient amount of moisture on the evaporating surface, evaporation cannot be large even with high temperature and a huge lack of moisture. Possible evaporation - evaporation- in this case is very large. Above the water surface, evaporation and evaporation coincide. Over land, evaporation can be much less than evaporation. Evaporation characterizes the amount of possible evaporation from land with sufficient moisture. Daily and annual variations in air humidity. Air humidity is constantly changing due to changes in the temperature of the evaporating surface and air, the ratio of evaporation and condensation processes, and moisture transfer.

Daily variation of absolute air humidity may be single or double. The first one coincides with the daily temperature variation, has one maximum and one minimum, and is typical for places with a sufficient amount of moisture. It can be observed over the Ocean, and in winter and autumn over land. The double move has two highs and two lows and is typical for land. The morning minimum before sunrise is explained by very weak evaporation (or even its absence) during the night hours. With an increase in the arrival of the radiant energy of the Sun, evaporation increases, the absolute humidity reaches a maximum at about 09:00. As a result, the developing convection - the transfer of moisture to the upper layers - occurs faster than its entry into the air from the evaporating surface, therefore, at about 16:00, a second minimum occurs. By evening, convection stops, and evaporation from the surface heated during the day is still quite intense and moisture accumulates in the lower layers of the air, creating a second (evening) maximum around 20-21 hours.

The annual course of absolute humidity also corresponds to the annual course of temperature. In summer the absolute humidity is the highest, in winter it is the lowest. The daily and annual course of relative humidity is almost everywhere opposite to the course of temperature, since the maximum moisture content increases faster than absolute humidity with increasing temperature.

The daily maximum of relative humidity occurs before sunrise, the minimum - at 15-16 hours. During the year, the maximum relative humidity, as a rule, falls on the coldest month, the minimum - on the warmest. The exceptions are areas in which moist winds blow from the sea in summer, and dry winds from the mainland in winter.

The distribution of air humidity. The moisture content in the air in the direction from the equator to the poles generally decreases from 18-20 mb to 1-2. The maximum absolute humidity (more than 30 g / m 3) was recorded over the Red Sea and in the delta of the river. Mekong, the largest average annual (more than 67 g / m 3) - over the Bay of Bengal, the smallest average annual (about 1 g / m 3) and the absolute minimum (less than 0.1 g / m 3) - over Antarctica. Relative humidity changes relatively little with latitude: for example, at latitudes 0-10° it is a maximum of 85%, at latitudes 30-40° - 70% and at latitudes 60-70° - 80%. A noticeable decrease in relative humidity is observed only at latitudes of 30-40° in the northern and southern hemispheres. The highest average annual value of relative humidity (90%) was observed at the mouth of the Amazon, the lowest (28%) - in Khartoum (Nile Valley).

condensation and sublimation. In air saturated with water vapor, when its temperature drops to the dew point or the amount of water vapor in it increases, condensation - water changes from a vapor state to a liquid state. At temperatures below 0 ° C, water can, bypassing the liquid state, go into a solid state. This process is called sublimation. Both condensation and sublimation can occur in the air on the nuclei of condensation, on the earth's surface and on the surface of various objects. When the temperature of the air cooling from the underlying surface reaches the dew point, dew, hoarfrost, liquid and solid deposits, and frost settle on the cold surface.

dew - tiny droplets of water, often merging. It usually appears at night on the surface, on the leaves of plants that have cooled as a result of heat radiation. In temperate latitudes, dew gives 0.1-0.3 mm per night, and 10-50 mm per year.

Hoarfrost - hard white precipitate. Formed under the same conditions as dew, but at temperatures below 0° (sublimation). When dew forms, latent heat is released; when frost forms, heat, on the contrary, is absorbed.

Liquid and solid plaque - thin film of water or ice that forms on vertical surfaces (walls, poles, etc.) when changing cold weather to warm as a result of contact of moist and warm air with a cooled surface.

Hoarfrost - white loose sediment that settles on trees, wires and the corners of buildings from air saturated with moisture at a temperature well below 0 °. called ice. It usually forms in autumn and spring at a temperature of 0°, -5°.

The accumulation of products of condensation or sublimation (water droplets, ice crystals) in the surface layers of air is called mist or haze. Fog and haze differ in droplet size and cause different degrees of reduced visibility. In fog, visibility is 1 km or less, in haze - more than 1 km. As the droplets get larger, the haze can turn into fog. Evaporation of moisture from the surface of the droplets can cause the fog to turn into haze.

If condensation (or sublimation) of water vapor occurs at a certain height above the surface, clouds. They differ from fog in their position in the atmosphere, in their physical structure, and in their variety of forms. The formation of clouds is mainly due to the adiabatic cooling of the rising air. Rising and at the same time gradually cooling, the air reaches the boundary at which its temperature is equal to the dew point. This border is called level of condensation. Above, in the presence of condensation nuclei, condensation of water vapor begins and clouds can form. Thus, the lower boundary of the clouds practically coincides with the level of condensation. The upper boundary of the clouds is determined by the level of convection - the boundaries of the distribution of ascending air currents. It often coincides with the delay layers.

At high altitude, where the temperature of the rising air is below 0°, ice crystals appear in the cloud. Crystallization usually occurs at a temperature of -10° C, -15° C. There is no sharp boundary between the location of liquid and solid elements in the cloud, there are powerful transitional layers. The water droplets and ice crystals that make up the cloud are carried upward by the ascending currents and descend again under the action of gravity. Falling below the condensation limit, the droplets can evaporate. Depending on the predominance of certain elements, clouds are divided into water, ice, mixed.

Water Clouds are made up of water droplets. At a negative temperature, the droplets in the cloud are supercooled (down to -30°C). The droplet radius is most often from 2 to 7 microns, rarely up to 100 microns. In 1 cm 3 of a water cloud there are several hundred droplets.

Ice Clouds are made up of ice crystals.

mixed contain water droplets of different sizes and ice crystals at the same time. In the warm season, water clouds appear mainly in the lower layers of the troposphere, mixed - in the middle, ice - in the upper. The modern international classification of clouds is based on their division by height and appearance.

According to their appearance and height, the clouds are divided into 10 genera:

I family (upper tier):

1st kind. Cirrus (C)- separate delicate clouds, fibrous or threadlike, without "shadows", usually white, often shining.

2nd kind. Cirrocumulus (CC) - layers and ridges of transparent flakes and balls without shadows.

3rd kind. Cirrostratus (Cs) - thin, white, translucent shroud.

All clouds of the upper tier are icy.

II family (middle tier):

4th kind. Altocumulus(AC) - layers or ridges of white plates and balls, shafts. They are made up of tiny water droplets.

5th kind. Altostratus(As) - smooth or slightly wavy veil of gray color. They are mixed clouds.

III family (lower tier):

6th kind. Stratocumulus(Sс) - layers and ridges of blocks and shafts of gray color. Made up of water droplets.

7th kind. layered(St) - veil of gray clouds. Usually these are water clouds.

8th kind. Nimbostratus(Ns) - shapeless gray layer. Often "; these clouds are accompanied by underlying ragged rain (fn),

Strato-nimbus clouds mixed.

IV family (clouds of vertical development):

9th kind. Cumulus(Si) - dense cloudy clubs and heaps with an almost horizontal base. Cumulus clouds are water. Cumulus clouds with torn edges are called torn cumulus. (Fc).

10th kind. Cumulonimbus(Sv) - dense clubs developed vertically, watery in the lower part, icy in the upper part.

The nature and shape of clouds are determined by processes that cause air cooling, leading to cloud formation. As a result convection, A heterogeneous surface that develops upon heating produces cumulus clouds (family IV). They differ depending on the intensity of convection and on the position of the level of condensation: the more intense the convection, the higher its level, the greater the vertical power of cumulus clouds.

When warm and cold air masses meet, warm air always tends to rise up cold air. As it rises, clouds form as a result of adiabatic cooling. If warm air slowly rises along a slightly inclined (1-2 km at a distance of 100-200 km) interface between warm and cold masses (ascending slip process), a continuous cloud layer is formed, extending for hundreds of kilometers (700-900 km). A characteristic cloud system emerges: ragged rain clouds are often found below (fn), above them - stratified rain (Ns), above - high-layered (As), cirrostratus (Cs) and cirrus clouds (WITH).

In the case when warm air is vigorously pushed upwards by cold air flowing under it, a different cloud system is formed. Since the surface layers of cold air due to friction move more slowly than the overlying layers, the interface in its lower part bends sharply, warm air rises almost vertically and cumulonimbus clouds form in it. (Cb). If an upward sliding of warm air over cold air is observed above, then (as in the first case) nimbostratus, altostratus and cirrostratus clouds develop (as in the first case). If the upward slide stops, clouds do not form.

Clouds formed when warm air rises over cold air are called frontal. If the rise of air is caused by its flow onto the slopes of mountains and hills, the clouds formed in this case are called orographic. At the lower boundary of the inversion layer, which separates denser and less dense layers of air, waves several hundred meters long and 20-50 m high appear. On the crests of these waves, where the air cools as it rises, clouds form; cloud formation does not occur in the depressions between the crests. So there are long parallel strips or shafts. wavy clouds. Depending on the height of their location, they are altocumulus or stratocumulus.

If there were already clouds in the atmosphere before the onset of wave motion, they become denser on the crests of the waves and the density decreases in depressions. The result is the often observed alternation of darker and lighter cloud bands. With turbulent mixing of air over a large area, for example, as a result of increased friction on the surface when it moves from the sea to land, a layer of clouds is formed, which differs in unequal power in different parts and even breaks. Heat loss by radiation at night in winter and autumn causes cloud formation in the air with a high content of water vapor. Since this process proceeds calmly and continuously, a continuous layer of clouds appears, melting during the day.

Storm. The process of cloud formation is always accompanied by electrification and accumulation of free charges in clouds. Electrification is observed even in small cumulus clouds, but it is especially intense in powerful cumulonimbus clouds of vertical development with a low temperature in the upper part (t

Between sections of the cloud with different charges or between the cloud and the ground, electrical discharges occur - lightning, accompanied thunder. This is a thunderstorm. The duration of a thunderstorm is a maximum of several hours. About 2,000 thunderstorms occur on Earth every hour. Favorable conditions for the occurrence of thunderstorms are strong convection and high water content of clouds. Therefore, thunderstorms are especially frequent over land in tropical latitudes (up to 150 days a year with thunderstorms), in temperate latitudes over land - with thunderstorms 10-30 days a year, over the sea - 5-10. Thunderstorms are very rare in the polar regions.

Light phenomena in the atmosphere. As a result of reflection, refraction and diffraction of light rays in droplets and ice crystals of clouds, halos, crowns, rainbows appear.

Halo - these are circles, arcs, light spots (false suns), colored and colorless, arising in the ice clouds of the upper tier, more often in cirrostratus. The diversity of the halo depends on the shape of the ice crystals, their orientation and movement; the height of the sun above the horizon matters.

Crowns - light, slightly colored rings surrounding the Sun or the Moon, which are translucent through thin water clouds. There may be one crown adjacent to the luminary (halo), and there may be several "additional rings" separated by gaps. Each crown has an inner side facing the star is blue, the outer side is red. The reason for the appearance of crowns is the diffraction of light as it passes between the droplets and crystals of the cloud. The dimensions of the crown depend on the size of the drops and crystals: the larger the drops (crystals), the smaller the crown, and vice versa. If cloud elements become larger in the cloud, the crown radius gradually decreases, and when the size of cloud elements decreases (evaporation), it increases. Large white crowns around the Sun or Moon "false suns"; pillars are signs of good weather.

Rainbow It is visible against the background of a cloud illuminated by the Sun, from which drops of rain fall. It is a light arc, painted in spectral colors: the outer edge of the arc is red, the inner edge is purple. This arc is a part of a circle, the center of which is connected by "; axis"; (one straight line) with the eye of the observer and with the center of the solar disk. If the Sun is low on the horizon, the observer sees half of the circle; if the Sun rises, the arc becomes smaller as the center of the circle falls below the horizon. When the sun is >42°, the rainbow is not visible. From an airplane, you can observe a rainbow in the form of an almost complete circle.

In addition to the main rainbow, there are secondary, slightly colored ones. A rainbow is formed by the refraction and reflection of sunlight in water droplets. The rays falling on the drops come out of the drops as if diverging, colored, and this is how the observer sees them. When the rays are refracted twice in a drop, a secondary rainbow appears. The color of the rainbow, its width, and the type of secondary arcs depend on the size of the droplets. Large drops give a smaller but brighter rainbow; as the drops decrease, the rainbow becomes wider, its colors become blurry; with very small drops, it is almost white. Light phenomena in the atmosphere, caused by changes in the light beam under the influence of droplets and crystals, make it possible to judge the structure and condition of clouds and can be used in weather predictions.

Cloudiness, daily and annual variation, distribution of clouds.

Cloudiness - the degree of cloud coverage of the sky: 0 - clear sky, 10 - overcast, 5 - half of the sky is covered with clouds, 1 - clouds cover 1/10 of the sky, etc. When calculating average cloudiness, tenths of a unit are also used, for example: 0.5 5.0, 8.7 etc. In the daily course of cloudiness over land, two maxima are found - in the early morning and in the afternoon. In the morning, a decrease in temperature and an increase in relative humidity contribute to the formation of stratus clouds; in the afternoon, due to the development of convection, cumulus clouds appear. In summer, the daily maximum is more pronounced than the morning one. In winter, stratus clouds predominate and the maximum cloudiness occurs in the morning and night hours. Over the Ocean, the daily course of cloudiness is the reverse of its course over land: the maximum cloudiness occurs at night, the minimum - during the day.

The annual course of cloudiness is very diverse. At low latitudes, cloud cover does not change significantly throughout the year. Over the continents, the maximum development of convection clouds occurs in summer. The summer cloudiness maximum is noted in the area of monsoon development, as well as over the oceans at high latitudes. In general, in the distribution of cloudiness on Earth, zoning is noticeable, due primarily to the prevailing movement of air - its rise or fall. Two maxima are noted - above the equator due to powerful upward movements of moist air and above 60-70 ° With. and y.sh. in connection with the rise of air in cyclones prevailing in temperate latitudes. Over land, cloudiness is less than over the ocean, and its zonality is less pronounced. Cloud minimums are confined to 20-30°S. and s. sh. and to the poles; they are associated with lowering air.

The average annual cloudiness for the whole Earth is 5.4; over land 4.9; over the Ocean 5.8. The minimum average annual cloudiness is noted in Aswan (Egypt) 0.5. The maximum average annual cloudiness (8.8) was observed in the White Sea; the northern regions of the Atlantic and Pacific oceans and the coast of Antarctica are characterized by large clouds.

Clouds play a very important role in geographical envelope. They carry moisture, rainfall is associated with them. The cloud cover reflects and scatters solar radiation and at the same time delays the thermal radiation of the earth's surface, regulating the temperature of the lower layers of the air: without clouds, fluctuations in air temperature would become very sharp.

Precipitation. Precipitation is water that has fallen to the surface from the atmosphere in the form of rain, drizzle, grains, snow, hail. Precipitation falls mainly from clouds, but not every cloud gives precipitation. The water droplets and ice crystals in the cloud are very small, easily held by the air, and even weak upward currents carry them upward. Precipitation requires cloud elements to grow large enough to overcome rising currents and air resistance. The enlargement of some elements of the cloud occurs at the expense of others, firstly, as a result of the merging of droplets and the adhesion of crystals, and secondly, and this is the main thing, as a result of evaporation of some elements of the cloud, diffuse transfer and condensation of water vapor on others.

The collision of drops or crystals occurs during random (turbulent) movements or when they fall at different speeds. The fusion process is hindered by a film of air on the surface of the droplets, which causes the colliding droplets to bounce, as well as electric charges of the same name. The growth of some cloud elements at the expense of others due to the diffuse transfer of water vapor is especially intense in mixed clouds. Since the maximum moisture content over water is greater than over ice, for ice crystals in a cloud, water vapor can saturate the space, while for water droplets there will be no saturation. As a result, the droplets will begin to evaporate, and the crystals will rapidly grow due to moisture condensation on their surface.

In the presence of droplets of different sizes in a water cloud, the movement of water vapor to larger drops begins and their growth begins. But since this process is very slow, very small drops (0.05-0.5 mm in diameter) fall out of water clouds (stratus, stratocumulus). Clouds that are homogeneous in structure usually do not produce precipitation. Especially favorable conditions for the occurrence of precipitation in clouds of vertical development. In the lower part of such a cloud there are water drops, in the upper part there are ice crystals, in the intermediate zone there are supercooled drops and crystals.

In rare cases, when there are a large number of condensation nuclei in very humid air, one can observe the precipitation of individual raindrops without clouds. Raindrops have a diameter of 0.05 to 7 mm (average 1.5 mm), larger droplets disintegrate in the air. Drops up to 0.5 mm in diameter form drizzle.

The falling drops of drizzle are imperceptible to the eye. Real rain is the larger, the stronger the ascending air currents overcome by falling drops. At an ascending air speed of 4 m / s, drops with a diameter of at least 1 mm fall on the earth's surface: ascending currents at a speed of 8 m / s cannot overcome even the largest drops. The temperature of the falling raindrops is always slightly lower than the air temperature. If the ice crystals falling from the cloud do not melt in the air, solid precipitation (snow, grains, hail) falls to the surface.

Snowflakes are hexagonal ice crystals with rays formed in the process of sublimation. Wet snowflakes stick together to form snow flakes. Snow pellet is spherocrystals arising from the random growth of ice crystals under conditions of high relative humidity (greater than 100%). If a snow pellet is covered with a thin shell of ice, it turns into ice grits.

hail falls in the warm season from powerful cumulonimbus clouds . Usually hail fall is short-lived. Hailstones are formed as a result of the repeated movement of ice pellets in the cloud up and down. Falling down, the grains fall into the zone of supercooled water droplets and are covered with a transparent ice shell; then they again rise to the zone of ice crystals and an opaque layer of tiny crystals forms on their surface.

The hailstone has a snow core and a series of alternating transparent and opaque ice shells. The number of shells and the size of the hailstone depend on how many times it rose and fell in the cloud. Most often, hailstones with a diameter of 6-20 mm fall out, sometimes there are much larger ones. Usually hail falls in temperate latitudes, but the most intense hail fall occurs in the tropics. In the polar regions, hail does not fall.

Precipitation is measured in terms of the thickness of the water layer in millimeters, which could be formed as a result of precipitation on a horizontal surface in the absence of evaporation and infiltration into the soil. According to the intensity (the number of millimeters of precipitation in 1 minute), precipitation is divided into weak, moderate and heavy. The nature of precipitation depends on the conditions of their formation.

overhead precipitation, characterized by uniformity and duration, usually fall in the form of rain from nimbostratus clouds.

heavy rainfall characterized by a rapid change in intensity and short duration. They fall from cumulus stratus clouds in the form of rain, snow, and occasional rain and hail. Separate showers with an intensity of up to 21.5 mm/min (Hawaiian Islands) were noted.

Drizzling precipitation fall out of stratocumulus and stratocumulus clouds. The droplets that make them up (in cold weather - the smallest crystals) are barely visible and seem to be suspended in the air.

The daily course of precipitation coincides with the daily course of cloudiness. There are two types of daily precipitation patterns - continental and marine (coastal). continental type has two maxima (in the morning and afternoon) and two minima (at night and before noon). marine type- one maximum (night) and one minimum (day). The annual course of precipitation is different in different latitudinal zones and in different parts of the same zone. It depends on the amount of heat, thermal regime, air movement, distribution of water and land, and to a large extent on topography. All the diversity of the annual course of precipitation cannot be reduced to several types, but it can be noted characteristics for different latitudes, allowing us to speak about its zonality. Equatorial latitudes are characterized by two rainy seasons (after the equinoxes) separated by two dry seasons. In the direction of the tropics, changes occur in the annual precipitation regime, expressed in the convergence of wet seasons and their confluence near the tropics into one season with heavy rains, lasting 4 months a year. In subtropical latitudes (35-40°) there is also one rainy season, but it falls in winter. In temperate latitudes, the annual course of precipitation is different over the Ocean, the interior of the continents, and the coasts. Winter precipitation prevails over the Ocean, and summer precipitation over the continents. Summer precipitation is also typical for polar latitudes. The annual course of precipitation in each case can be explained only by taking into account the circulation of the atmosphere.

Precipitation is most abundant in equatorial latitudes, where the annual amount exceeds 1000-2000 mm. On the equatorial islands of the Pacific Ocean falls up to 4000-5000 mm per year, and on the windward slopes of the mountains of tropical islands up to 10000 mm. Heavy rainfall is caused by powerful convective currents of very humid air. To the north and south of the equatorial latitudes, the amount of precipitation decreases, reaching a minimum near the 25-35 ° parallel, where their average annual amount is not more than 500 mm. In the interior of the continents and on the western coasts, rains do not fall in places for several years. In temperate latitudes, the amount of precipitation increases again and averages 800 mm per year; in the inner part of the continents there are fewer of them (500, 400 and even 250 mm per year); on the shores of the Ocean more (up to 1000 mm per year). At high latitudes, at low temperatures and low moisture content in the air, the annual amount of precipitation

The maximum average annual precipitation falls in Cherrapunji (India) - about 12,270 mm. The largest annual precipitation there is about 23,000 mm, the smallest - more than 7,000 mm. The minimum recorded average annual rainfall is in Aswan (0).

The total amount of precipitation falling on the Earth's surface in a year can form a continuous layer up to 1000 mm high on it.

Snow cover. Snow cover is formed by the fall of snow on the earth's surface at a temperature low enough to maintain it. It is characterized by height and density.

The height of the snow cover, measured in centimeters, depends on the amount of precipitation that has fallen on a unit of surface, on the density of snow (the ratio of mass to volume), on the terrain, on the vegetation cover, and also on the wind that moves the snow. In temperate latitudes, the usual height of the snow cover is 30-50 cm. Its highest height in Russia is noted in the basin of the middle reaches of the Yenisei - 110 cm. In the mountains, it can reach several meters.

Having a high albedo and high radiation, the snow cover contributes to lowering the temperature of the surface layers of air, especially in clear weather. The minimum and maximum air temperatures above the snow cover are lower than under the same conditions, but in the absence of it.

In the polar and high-mountain regions, snow cover is permanent. In temperate latitudes, the duration of its occurrence varies depending on climatic conditions. Snow cover that persists for a month is called stable. Such snow cover is formed annually in most of the territory of Russia. In the Far North, it lasts 8-9 months, in the central regions - 4-6, on the shores of the Azov and Black Seas, the snow cover is unstable. Snow melting is mainly caused by exposure to warm air coming from other areas. Under the action of sunlight, about 36% of the snow cover melts. Warm rain helps melt. Contaminated snow melts faster.

Snow not only melts, but also evaporates in dry air. But the evaporation of snow cover is less important than melting.

Hydration. To estimate the surface moistening conditions, it is not enough to know only the amount of precipitation. With the same amount of precipitation, but different evapotranspiration, the moistening conditions can be very different. To characterize the conditions of moisture, use moisture coefficient (K), representing the ratio of the amount of precipitation (r) to evaporation (Eat) for the same period.

Moisture is usually expressed as a percentage, but it can be expressed as a fraction. If the amount of precipitation is less than evaporation, i.e. TO less than 100% (or TO less than 1), moisture is insufficient. At TO more than 100% moisture may be excessive, at K=100% it is normal. If K=10% (0.1) or less than 10%, we speak of negligible moisture.

In semi-deserts, K is 30%, but 100% (100-150%).

During the year, an average of 511 thousand km 3 of precipitation falls on the earth's surface, of which 108 thousand km 3 (21%) fall on land, the rest in the Ocean. Almost half of all precipitation falls between 20°N. sh. and 20°S sh. The polar regions account for only 4% of precipitation.

On average, as much water evaporates from the Earth's surface in a year as falls on it. The main ";source"; moisture in the atmosphere is Ocean in subtropical latitudes, where surface heating creates conditions for maximum evaporation at a given temperature. In the same latitudes on land, where evaporation is high, and there is nothing to evaporate, drainless regions and deserts arise. For the Ocean as a whole, the balance of water is negative (evaporation is more precipitation), on land it is positive (evaporation is less precipitation). The overall balance is equalized by means of a drain "surplus"; water from land to ocean.

mode atmosphere The Earth has been investigated as ... influence on radiation and thermalmodeatmosphere determining the weather and... surfaces. Most of thermal the energy it receives atmosphere, comes from underlyingsurfaces... Thermal regime of the atmosphere

local temperature

The total temperature change in the fixed
geographic point, depending on individual
changes in the state of the air, and from advection, are called
local (local) change.
Any meteorological station, which does not change
its position on the earth's surface,
be considered as such a point.
Meteorological instruments - thermometers and
thermographs, fixedly placed in one or another
place, register exactly local changes
air temperature.
A thermometer on a balloon flying in the wind and,
therefore remaining in the same mass
air, shows individual change
temperature in this mass.

Thermal regime of the atmosphere

Air temperature distribution in
space and its change in time
Thermal state of the atmosphere
defined:
1. Heat exchange with the environment
(with underlying surface, adjacent
air masses and outer space).
2. Adiabatic processes
(associated with changes in air pressure,
especially when moving vertically
3. Advection processes
(the transfer of warm or cold air that affects the temperature in
given point)

Heat exchange

Heat transfer paths
1) Radiation
in absorption
air radiation from the sun and the earth
surfaces.
2) Thermal conductivity.
3) Evaporation or condensation.
4) Formation or melting of ice and snow.

Radiative heat transfer path

1. Direct absorption
there is little solar radiation in the troposphere;
it can cause an increase
air temperature by just
about 0.5° per day.
2. Somewhat more important is
loss of heat from the air
longwave radiation.

B = S + D + Ea – Rk – Rd – Ez, kW/m2
Where
S - direct solar radiation on
horizontal surface;
D - scattered solar radiation on
horizontal surface;
Ea is the counter radiation of the atmosphere;
Rk and Rd - reflected from the underlying surface
short and long wave radiation;
Ez - long-wave radiation of the underlying
surfaces.

Radiation balance of the underlying surface

B = S + D + Ea– Rk – Rd – Ez, kW/m2
Pay attention to:
Q = S + D This is the total radiation;
Rd is a very small value and is usually not
take into account;
Rk =Q *Ak, where A is the albedo of the surface;
Eef \u003d Ez - Ea
We get:
B \u003d Q (1 - Ak) - Eef

Thermal balance of the underlying surface

B \u003d Lt-f * Mp + Lzh-g * Mk + Qa + Qp-p
where Lt-zh and Lzh-g - specific heat of fusion
and vaporization (condensation), respectively;
Mn and Mk are the masses of water involved in
corresponding phase transitions;
Qa and Qp-p - heat flux into the atmosphere and through
underlying surface to underlying layers
soil or water.

surface and active layer

The temperature regime of the underlying

The underlying surface is
ground surface (soil, water, snow and
etc.), interacting with the atmosphere
in the process of heat and moisture exchange.
The active layer is the layer of soil (including
vegetation and snow cover) or water,
participating in heat exchange with the environment,
to the depth of which the daily and
annual temperature fluctuations.

10. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
In the soil, solar radiation, penetrating
to a depth of tenths of a mm,
converted into heat, which
transmitted to the underlying layers
molecular thermal conductivity.
In water, solar radiation penetrates
depths up to tens of meters, and the transfer
heat to the underlying layers occurs in
turbulent
mixing, thermal
convection and evaporation

11. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
Daily temperature fluctuations
apply:
in water - up to tens of meters,
in the soil - less than a meter
Annual temperature fluctuations
apply:
in water - up to hundreds of meters,
in the soil - 10-20 meters

12. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
The heat that comes to the surface of the water during the day and summer penetrates
to a considerable depth and heats a large water column.
The temperature of the upper layer and the very surface of the water
it rises little.
In the soil, the incoming heat is distributed in a thin upper
layer, which thus becomes very hot.
At night and in winter, water loses heat from the surface layer, but
instead of it comes the accumulated heat from the underlying layers.
Therefore, the temperature at the surface of the water decreases
slowly.
On the surface of the soil, the temperature drops when heat is released
fast:
heat accumulated in a thin upper layer quickly leaves it
without replenishment from below.

13. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
During the day and summer, the temperature on the soil surface is higher than the temperature on
water surface; lower at night and in winter.
The daily and annual fluctuations in temperature on the soil surface are greater,
moreover, much more than on the surface of the water.
During the warm season, the water basin accumulates in a fairly thick layer
water, a large amount of heat, which gives off to the atmosphere in a cold
season.
The soil during the warm season gives off most of the heat at night,
which receives during the day, and accumulates little of it by winter.
In the middle latitudes, during the warm half of the year, 1.5-3
kcal of heat per square centimeter of surface.
In cold weather, the soil gives off this heat to the atmosphere. Value ±1.5-3
kcal/cm2 per year is the annual heat cycle of the soil.
Under the influence of snow cover and vegetation in summer, the annual
soil heat circulation decreases; for example, near Leningrad by 30%.
In the tropics, the annual heat turnover is less than in temperate latitudes, since
there are less annual differences in the influx of solar radiation.

14. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
The annual heat turnover of large reservoirs is about 20
times more than the annual heat turnover
soil.
The Baltic Sea gives off air in cold weather 52
kcal / cm2 and accumulates the same amount in the warm season.
Annual heat turnover of the Black Sea ±48 kcal/cm2,
As a result of these differences, the air temperature above
lower by sea in summer and higher in winter than over land.

15. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
The land heats up quickly and
cools down.
The water heats up slowly and slowly
cools down
(specific heat capacity of water in
3-4 times more soil)
Vegetation reduces the amplitude
diurnal temperature fluctuations
soil surface.
The snow cover protects the soil from
intense heat loss (in winter, the soil
freezes less)

16.

key role in creating
temperature regime of the troposphere
heat exchange plays
air with the earth's surface
by conduction

17. Processes affecting the heat transfer of the atmosphere

Processes affecting heat transfer
atmosphere
1).Turbulence
(mixing
air with disordered
chaotic movement).
2).Thermal
convection
(air transport in vertical
direction that occurs when
heating of the underlying layer)

18. Changes in air temperature

Changes in air temperature
1).
Periodic
2). Non-periodic
Non-periodic changes
air temperature
Associated with advection of air masses
from other parts of the earth
Such changes are frequent and significant in
temperate latitudes,
they are associated with cyclonic
activities, in small
scales - with local winds.

19. Periodic changes in air temperature

Daily and annual temperature changes are
periodic character.
Diurnal Changes
The air temperature changes in
daily course following the temperature
earth's surface, from which
air is heated

20. Daily temperature variation

Daily temperature variation
Multi-annual diurnal curves
temperatures are smooth curves,
similar to sinusoids.
In climatology, it is considered
diurnal change in air temperature,
averaged over many years.

21. on the soil surface (1) and in the air at a height of 2m (2). Moscow (MSU)

The average diurnal temperature variation at the surface
soil (1) and
in the air at a height of 2m (2). Moscow (MSU)

22. Average daily temperature variation

Average daily temperature variation
The temperature on the soil surface has a diurnal variation.
Its minimum is observed approximately half an hour after
sunrise.
By this time, the radiation balance of the soil surface
becomes equal to zero - heat transfer from the upper layer
soil effective radiation is balanced
increased influx of total radiation.
The non-radiative heat exchange at this time is negligible.

23. Average daily temperature variation

Average daily temperature variation
The temperature on the soil surface rises up to 13-14 hours,
when it reaches its maximum in the daily course.
After that, the temperature starts to drop.
The radiation balance in the afternoon hours, however,
remains positive; however
heat transfer in the daytime from the top layer of soil to
atmosphere occurs not only through effective
radiation, but also through increased thermal conductivity, and
also with increased evaporation of water.
The transfer of heat into the depth of the soil also continues.
Therefore, the temperature on the surface of the soil and falls
from 13-14 hours to the morning low.

24. 25. Soil surface temperature

The maximum temperatures at the soil surface are usually higher
than in the air at the height of the meteorological booth. It's clear:
during the day, solar radiation primarily heats the soil, and already
it heats up the air.
In the Moscow region in the summer on the surface of bare soil
temperatures up to + 55 ° are observed, and in deserts - even up to + 80 °.
Nighttime temperature minima, on the contrary, occur at
the soil surface is lower than in the air,
since, first of all, the soil is cooled by effective
radiation, and already from it the air is cooled.
In winter in the Moscow region, night temperatures on the surface (at this time
covered with snow) can fall below -50 °, in summer (except July) - to zero. On
snow surface in the interior of Antarctica, even the average
the monthly temperature in June is about -70°, and in some cases it can
fall to -90°.

26. Daily temperature range

Daily temperature range
This is the difference between the maximum
and daily minimum temperature.
Daily temperature range
air changes:
by the seasons of the year,
by latitude
depending on the nature
underlying surface,
depending on the terrain.

27. Changes in the daily temperature amplitude (Asut)

Changes

1. In winter, Asut is less than in summer
2. With increasing latitude, A day. decreasing:
at latitude 20 - 30°
on land A days = 12 ° С
at a latitude of 60° A day. = 6°C
3. Open spaces
are characterized by a greater A day. :
for steppes and deserts medium
Asut \u003d 15-20 ° С (up to 30 ° С),

28. Changes in the daily temperature amplitude (Asut)

Changes
daily temperature amplitude (Asut)
4. Proximity of water basins
reduces A day.
5.On convex landforms
(tops and slopes of mountains) A day. less,
than on the plain
6. In concave landforms
(hollows, valleys, ravines, etc. And more days.

29. Influence of soil cover on soil surface temperature

Vegetation cover reduces soil cooling at night.
Night radiation occurs mainly with
the surface of the vegetation itself, which will be the most
cool.
The soil under vegetation retains a higher
temperature.
However, during the day, vegetation prevents radiation
heating the soil.
Daily temperature range under vegetation,
thus reduced, and the average daily temperature
lowered.
So, vegetation cover generally cools the soil.
In the Leningrad Region, the soil surface under field
crops may be 15° colder during the daytime than
fallow soil. On average, it is colder per day
exposed soil by 6°, and even at a depth of 5-10 cm remains
a difference of 3-4°.

30. Influence of soil cover on soil surface temperature

Snow cover protects the soil in winter from excessive heat loss.
Radiation comes from the surface of the snow cover itself, and the soil under it
stays warmer than bare soil. At the same time, the daily amplitude
temperatures on the soil surface under the snow drops sharply.
In the middle zone of the European territory of Russia with a snow cover of height
40-50 cm, the temperature of the soil surface under it is 6-7 ° higher than
the temperature of the bare soil, and 10° higher than the temperature on
the surface of the snow cover itself.
Winter soil freezing under snow reaches depths of about 40 cm, and without
snow can extend to depths of more than 100 cm.
So, the vegetation cover in summer reduces the temperature on the soil surface, and
snow cover in winter, on the contrary, increases it.
The combined effect of vegetation cover in summer and snow cover in winter reduces
annual amplitude of temperature on the soil surface; this reduction is
about 10° compared to bare soil.

31. Distribution of heat deep into the soil

The greater the density and moisture content of the soil, the
the better it conducts heat, the faster
spread deeper and deeper
temperature fluctuations penetrate.
Regardless of soil type, the oscillation period
temperature does not change with depth.
This means that not only on the surface, but also on
depths remains a daily course with a period of 24
hours between each two consecutive
highs or lows
and an annual course with a period of 12 months.

32. Distribution of heat deep into the soil

The oscillation amplitudes decrease with depth.
Increasing depth in arithmetic progression
leads to a progressive decrease in amplitude
geometric.
So, if on the surface the daily amplitude is 30°, and
at a depth of 20 cm 5 °, then at a depth of 40 cm it will be narrower
less than 1°.
At some relatively shallow depth, the daily
amplitude decreases so much that it becomes
practically equal to zero.
At this depth (about 70-100 cm, in different cases
different) begins a layer of constant daily
temperature.

33. Daily variation of temperature in the soil at different depths from 1 to 80 cm. Pavlovsk, May.

34. Annual temperature fluctuations

The amplitude of annual temperature fluctuations decreases from
depth.
However, annual fluctuations extend to a larger
depth, which is quite understandable: for their distribution
there is more time.
The amplitudes of annual fluctuations decrease almost to
zero at a depth of about 30 m in polar latitudes,
about 15-20 m in middle latitudes,
about 10 m in the tropics
(where and on the soil surface the annual amplitudes are smaller,
than in mid-latitudes).
At these depths begins, a layer of constant annual
temperature.

35.

The timing of the maximum and minimum temperatures
both in the daily and in the annual course they lag with depth
in proportion to her.
This is understandable, since it takes time for the heat to spread through
depth.
Daily extremes for every 10 cm of depth are delayed by
2.5-3.5 hours.
This means that at a depth of, for example, 50 cm, the daily maximum
seen after midnight.
Annual highs and lows are 20-30 days late by
every meter of depth.
So, in Kaliningrad at a depth of 5 m, the minimum temperature
observed not in January, as on the soil surface, but in May,
maximum - not in July, but in October

36. Annual variation of temperature in the soil at different depths from 3 to 753 cm in Kaliningrad.

37. Temperature distribution in the soil vertically in different seasons

In summer, the temperature drops from the soil surface to the depth.
Grows in winter.
In the spring, it first grows, and then decreases.
In autumn, it first decreases and then grows.
Changes in temperature in the soil with depth during the day or year can be represented with
using an isopleth chart.
The x-axis represents time in hours or months of the year.
The y-axis is the depth in the soil.
Each point on the graph corresponds to a certain time and a certain depth. On
graph plots average temperatures at different depths at different hours or
months.
After drawing isolines connecting points with equal temperatures,
for example, every degree or every 2 degrees, we get a family
thermal isopleth.
According to this graph, you can determine the temperature value for any moment of the day.
or day of the year and for any depth within the graph.

38. Isopleths of the annual temperature variation in the soil in Tbilisi

Isoplets of the annual temperature variation in the soil in
Tbilisi

39. Daily and annual course of temperature on the surface of reservoirs and in the upper layers of water

Heating and cooling spreads in water bodies for more than
thick layer than in the soil, and in addition having a greater
heat capacity than soil.
As a result of this change in temperature at the surface of the water
very small.
Their amplitude is of the order of tenths of a degree: about 0.1-
0.2° in temperate latitudes,
about 0.5° in the tropics.
In the southern seas of the USSR, the daily temperature amplitude is greater:
1-2°;
on the surface of large lakes in temperate latitudes even more:
2-5°.
Diurnal fluctuations in ocean surface water temperature
have a maximum of about 15-16 hours and a minimum after 2-3 hours
after sunrise.

40. Daily variation of temperature at the sea surface (solid curve) and at a height of 6 m in the air (dashed curve) in a tropical

Atlantic

41. Daily and annual course of temperature on the surface of reservoirs and in the upper layers of water

Annual amplitude of surface temperature fluctuations
ocean much more than the daily.
But it is less than the annual amplitude on the soil surface.
In the tropics, it is about 2-3 °, at 40 ° N. sh. about 10 °, and at 40 ° S.
sh. around 5°.
On inland seas and deep-sea lakes,
significantly large annual amplitudes - up to 20° or more.
Both daily and annual fluctuations propagate in water
(also, of course, belatedly) to greater depths than in soil.
Daily fluctuations are found in the sea at depths up to 15
20 m and more, and annual - up to 150-400 m.

42. Daily variation of air temperature near the earth's surface

Air temperature changes daily
following the temperature of the earth's surface.
As the air is heated and cooled by
the earth's surface, the amplitude of the diurnal variation
the temperature in the meteorological booth is lower,
than on the soil surface, on average about
by one third.

43. Daily variation of air temperature near the earth's surface

An increase in air temperature begins with an increase in
soil temperature (15 minutes later) in the morning,
after sunrise. At 13-14 hours the soil temperature,
starts to drop.
At 14-15 hours it equalizes with the air temperature;
From now on, with a further drop in temperature
the soil starts to drop and the air temperature.
Thus, the minimum in the daily course of temperature
air at the earth's surface falls on time
shortly after sunrise,
and a maximum of 14-15 hours.

44. Daily variation of air temperature near the earth's surface

The daily course of air temperature is quite correct
manifests itself only in stable clear weather.
It seems even more logical on average from a large
number of observations: long-term diurnal curves
temperature - smooth curves, similar to sinusoids.
But on some days, the diurnal variation of air temperature can
be very wrong.
It depends on changes in cloudiness that change the radiative
conditions on the earth's surface, as well as from advection, i.e. from
inflow of air masses with a different temperature.
As a result of these reasons, the temperature minimum may shift
even during the daytime, and a maximum - at night.
The diurnal variation of temperature may disappear altogether or the curve
diurnal change will take a complex and irregular form.

45. Daily variation of air temperature near the earth's surface

The regular diurnal course is overlapped or masked
non-periodic temperature changes.
For example, in Helsinki in January there are 24%
the probability that the daily temperature maximum
be between midnight and one in the morning, and
only 13% chance that it will fall on
time interval from 12 to 14 hours.
Even in the tropics, where non-periodic temperature changes are weaker than in temperate latitudes, the maximum
temperatures are in the afternoon
only in 50% of all cases.

46. Daily variation of air temperature near the earth's surface

In climatology, the diurnal variation is usually considered
air temperature averaged over a long period.
In such an average daily course, non-periodic changes
temperatures that fall more or less evenly across
all hours of the day cancel each other out.
As a result, the long-term diurnal variation curve has
simple character close to sinusoidal.
For example, consider the daily variation of air temperature in
Moscow in January and July, calculated by multi-year
data.
The long-term average temperature was calculated for each hour
January or July days, and then according to the obtained average
hourly values were constructed long-term curves
daily course for January and July.

47. Daily course of air temperature in Moscow in January and July. The figures indicate the average monthly temperatures of January and July.

48. Daily changes in the amplitude of air temperature

The daily amplitude of air temperature varies by season,
latitude, as well as depending on the nature of the soil and
terrain.
In winter, it is less than in summer, as well as the amplitude
underlying surface temperature.
With increasing latitude, the daily temperature amplitude
air decreases as the midday height of the sun decreases
over the horizon.
Under latitudes of 20-30 ° on land, the annual average daily
temperature amplitude about 12°,
under latitude 60° about 6°,
under latitude 70° only 3°.
In the highest latitudes where the sun does not rise or
comes many days in a row, regular daily course
no temperature at all.

49. Influence of the nature of the soil and soil cover

The greater the diurnal range of temperature itself
soil surface, the greater the daily amplitude
air temperature above it.
In the steppes and deserts, the average daily amplitude
reaches 15-20°, sometimes 30°.
It is smaller above the abundant vegetation cover.
The proximity of water sources also affects the diurnal amplitude.
basins: in coastal areas it is lowered.

50. Relief influence

On convex landforms (on the peaks and on
slopes of mountains and hills) daily temperature range
air is reduced in comparison with the flat terrain.
In concave landforms (in valleys, ravines and hollows)
increased.
The reason is that on convex landforms
air has a reduced area of contact with
underlying surface and is quickly removed from it, being replaced
new masses of air.
In concave landforms, the air heats up more strongly from
surface and stagnates more during the daytime, and at night
cools more strongly and flows down the slopes. But in narrow
gorges, where both the influx of radiation and effective radiation
reduced, diurnal amplitudes are less than in wide
valleys

51. Influence of the seas and oceans

Small diurnal temperature amplitudes on the surface
seas also have small diurnal amplitudes
air temperature over the sea.
However, these latter are still higher than the daily
amplitudes on the sea surface itself.
Diurnal amplitudes on the surface of the open ocean
measured only in tenths of a degree;
but in the lower layer of air above the ocean they reach 1 -
1.5°),
and more over inland seas.
The temperature amplitudes in the air are increased because
they are influenced by the advection of air masses.
Direct absorption also plays a role.
solar radiation by the lower layers of air during the day and
radiation from them at night.

52. Change in daily temperature amplitude with height

Daily temperature fluctuations in the atmosphere extend to
a more powerful layer than the diurnal fluctuations in the ocean.
At an altitude of 300 m above land, the amplitude of the daily temperature variation
about 50% of the amplitude at the earth's surface, and the extreme values
temperatures come 1.5-2 hours later.
At an altitude of 1 km, the daily temperature range over land is 1-2°,
at a height of 2-5 km 0.5-1 °, and the daytime maximum shifts to
evening.
Over the sea, the daily temperature amplitude slightly increases with
high in the lower kilometers, but still remains small.
Small diurnal temperature fluctuations are detected even
in the upper troposphere and in the lower stratosphere.
But there they are already determined by the processes of absorption and emission
radiation by air, and not by the influences of the earth's surface.

53. The influence of the terrain

In the mountains, where the influence of the underlying surface is greater than on
corresponding altitudes in free atmosphere, daily
amplitude decreases with height more slowly.
On individual mountain peaks, at altitudes of 3000 m and more,
the daily amplitude can still be 3-4°.
On high, vast plateaus, the diurnal temperature range
air of the same order as in the lowlands: absorbed radiation
and the effective radiation is large here, as is the surface
contact of air with soil.
The daily range of air temperature at Murghab station at
In the Pamirs, the annual average is 15.5°, while in Tashkent it is 12°.

54. 55. Radiation of the earth's surface

Top layers of soil and water, snowy
cover and vegetation themselves radiate
longwave radiation; this earthly
radiation is often referred to as intrinsic
radiation from the earth's surface.

56. Radiation of the earth's surface

Absolute temperatures of the earth's surface
are between 180 and 350°.
At these temperatures, the emitted radiation
practically lies within
4-120 microns,
and the maximum of its energy falls on the wavelengths
10-15 microns.
Therefore, all this radiation
infrared, invisible to the eye.

57. 58. Atmospheric radiation

The atmosphere heats up by absorbing both solar radiation
(although in a relatively small proportion, about 15% of its total
amount coming to the Earth), and its own
radiation from the earth's surface.
In addition, it receives heat from the earth's surface.
by conduction of heat, as well as by evaporation and
subsequent condensation of water vapor.
Being heated, the atmosphere radiates itself.
Just like the earth's surface, it radiates an invisible
infrared radiation in the same range
wavelengths.

59. Counter radiation

Most (70%) of atmospheric radiation comes from
the earth's surface, the rest goes into the world
space.
Atmospheric radiation reaching the earth's surface is called counterradiation.
Oncoming because it is directed towards
self-radiation of the earth's surface.
The earth's surface absorbs this counter radiation
almost entirely (by 90-99%). Thus, it is
for the earth's surface an important source of heat in
addition to the absorbed solar radiation.

60. Counter radiation

Counter radiation increases with increasing cloudiness,
because the clouds themselves radiate strongly.
For flat stations of temperate latitudes, the average
counter radiation intensity (for each
square centimeter of horizontal earth
surface per minute)
about 0.3-0.4 cal,
at mountain stations - about 0.1-0.2 cal.
This is a decrease in counter radiation with height
due to the decrease in water vapor content.
The largest counter radiation is at the equator, where
the atmosphere is the hottest and richest in water vapor.
At the equator 0.5-0.6 cal/cm2 min on average,
In polar latitudes up to 0.3 cal/cm2 min.

61. Counter radiation

The main substance in the atmosphere that absorbs
terrestrial radiation and sending oncoming
radiation, is water vapor.
It absorbs infrared radiation in a large
spectral region - from 4.5 to 80 microns, with the exception of
interval between 8.5 and 11 microns.
With an average content of water vapor in the atmosphere
radiation with wavelengths from 5.5 to 7.0 microns or more
absorbed almost completely.
Only in the range of 8.5-11 microns terrestrial radiation
passes through the atmosphere into outer space.

62.

63. 64. Effective Radiation

The counter radiation is always somewhat less than the terrestrial one.
At night, when there is no solar radiation, the earth's surface comes
only counter radiation.
The earth's surface loses heat due to the positive difference between
own and counter radiation.
The difference between the earth's own radiation
surface and counter radiation of the atmosphere
called effective radiation

65. Efficient Radiation

Effective radiation is
net loss of radiant energy, and
hence the heat from the earth's surface
at night

66. Effective Radiation

With increasing cloudiness, increasing
counter radiation, effective radiation
decreases.
In cloudy weather, effective radiation
much less than in clear;
In cloudy weather less and night
cooling of the earth's surface.

67. Effective Radiation

Effective radiation, of course,
also exists during the day.
But during the day it overlaps or partially
compensated by the absorbed solar
radiation. Therefore, the earth's surface
warmer during the day than at night, as a result of which,
among other things, and effective radiation
more during the day.

68. Effective Radiation

Absorbing terrestrial radiation and sending oncoming
radiation to the earth's surface, atmosphere
most reduces the cooling of the latter in
night time.
During the day, it does little to prevent the heating of the earth.
surface by solar radiation.
This is the influence of the atmosphere on the thermal regime of the earth
surface is called the greenhouse effect.
due to external analogy with the action of glasses
greenhouses.

69. Effective Radiation

In general, the earth's surface in medium
latitudes loses effective
radiation about half that
the amount of heat she receives
from absorbed radiation.

70. Radiation balance of the earth's surface

The difference between the absorbed radiation and the radiation balance of the earth's surface In the presence of snow cover, the radiation balance
goes to positive values only at height
the sun is about 20-25 °, since with a large snow albedo
its absorption of total radiation is small.
During the day, the radiation balance increases with increasing altitude.
sun and decreases with its decrease.
At night, when there is no total radiation,
the negative radiation balance is
effective radiation
and therefore changes little during the night, unless
cloud conditions remain the same.

76. Radiation balance of the earth's surface

Mean noon values
radiation balance in Moscow:
in summer with a clear sky - 0.51 kW / m2,
in winter with a clear sky - 0.03 kW / m2
summer under average conditions
cloudiness - 0.3 kW / m2,
winter under average conditions
cloud cover is about 0 kW/m2.

77.

78. 79. Radiation balance of the earth's surface

The radiation balance is determined by a balance meter.
It has one blackened receiving plate
pointing up towards the sky
and the other - down to the earth's surface.
The difference in plate heating allows
determine the value of the radiation balance.
At night, it is equal to the value of the effective
radiation.

80. Radiation into world space

Most of the radiation from the earth's surface
absorbed in the atmosphere.
Only in the wavelength range of 8.5-11 microns passes through
atmosphere in the world space.
This outgoing amount is only 10%, of
influx of solar radiation to the boundary of the atmosphere.
But, in addition, the atmosphere itself radiates into the world
space about 55% of the energy from the incoming
solar radiation,
i.e., several times larger than the earth's surface.

81. Radiation into the world space

Radiation from the lower layers of the atmosphere is absorbed in
its overlying layers.
But, as you move away from the earth's surface, the content
water vapor, the main absorber of radiation,
decreases, and an increasingly thicker layer of air is needed,
to absorb radiation coming from
the underlying layers.
Starting from some height of water vapor in general
not enough to absorb all the radiation,
coming from below, and from these upper layers part
atmospheric radiation will go into the world
space.
Calculations show that the most strongly radiating in
Space layers of the atmosphere lie at altitudes of 6-10 km.

82. Radiation into the world space

Long-wave radiation of the earth's surface and
atmosphere going into space is called
outgoing radiation.
It is about 65 units, if we take for 100 units
influx of solar radiation into the atmosphere. Together with
reflected and scattered shortwave solar
radiation that escapes the atmosphere in
an amount of about 35 units (planetary albedo of the Earth),
this outgoing radiation compensates for the influx of solar
radiation to the earth.
Thus, the Earth, along with the atmosphere, loses
as much radiation as it receives, i.e.
is in a state of radiant (radiation)
balance.

83. Radiation balance

Qincoming = Qoutput
Qincoming \u003d I * S projections * (1-A)
σ
1/4
T =
Q flow = S earth * * T4
T=
0
252K

84. Physical constants

I - Solar constant - 1378 W/m2
R(Earth) - 6367 km.
A - the average albedo of the Earth - 0.33.
Σ - Stefan-Boltzmann constant -5.67 * 10 -8
W/m2K4