Temperature distribution on the ground in July and January. What are the regularities in the distribution of air temperature on Earth? Change in temperature with altitude Distribution of air temperature and atmospheric pressure

Geographical distribution of air temperature near the earth's surface

1. Considering the maps of the long-term average distribution of air temperature at sea level for individual calendar months and for the entire year, we find a number of patterns in this distribution that indicate the influence of geographical factors.

This is primarily the effect of latitude. The temperature generally decreases from the equator to the poles in accordance with the distribution of the radiation balance of the earth's surface. This decrease is especially significant in each hemisphere in winter, because near the equator the temperature changes little in annual course, and at high latitudes in winter it is much lower than in summer.

However, the isotherms on the maps do not quite coincide with the latitudinal circles, as well as the isolines of the radiation balance. They deviate especially strongly from zoning in the northern hemisphere. This clearly shows the influence of the division of the earth's surface on land and sea, which we will consider in more detail later. In addition, perturbations in the temperature distribution are associated with the presence of snow or ice cover, mountain ranges, warm and cold ocean currents. Finally, the characteristics of the general circulation of the atmosphere also influence the temperature distribution. After all, the temperature in each given place is determined not only by the conditions of the radiation balance in this place, but also by the transfer of air from other areas. For example, the lowest temperatures in Eurasia are not found in the center of the continent, but are strongly shifted to its eastern part. In the western part of Eurasia, temperatures are higher in winter and lower in summer than in the eastern part, precisely because with the prevailing westerly direction of air currents from the west, masses of sea air from the west penetrate far into Eurasia. Atlantic Ocean.

2. Year. Deviations from latitudinal circles are smallest on the map of mean annual temperatures for sea level (map XI). In winter, the continents are colder than the oceans, and warmer in summer; therefore, in the average annual values, the opposite deviations of the isotherms from the zonal distribution are partially mutually compensated. On the average annual map, we find on both sides of the equator in the tropics a wide zone where the average annual temperatures are above 25 ° C. Within this zone, heat islands over North Africa and, less significant in size, over India and Mexico, where the average annual temperature is above 28 ° C, are outlined by closed isotherms. There are no such heat islands over South America, South Africa, and Australia; however, over these continents, the isotherms bend to the south, forming<языки тепла>: high temperatures spread here further towards high latitudes than over the oceans. We see, therefore, that in the tropics, on average annual continents warmer than the oceans (we are talking about the temperature of the air above them).

At extratropical latitudes, isotherms deviate less from latitudinal circles, especially in the southern hemisphere, where the underlying surface at middle latitudes is an almost continuous ocean. But in the northern hemisphere, we still find in the middle and high latitudes more or less noticeable deviations of the isotherms to the south over the continents of Asia and North America. This means that, on an average annual basis, the continents in these latitudes are somewhat colder than the oceans.

The warmest places on the Earth in the average annual lie on the coasts of the southern part of the Red Sea. In Massawa (Eritrea, 15.6°N, 39.4°E), the average annual temperature at sea level is 30°C, and in Hodeida (Yemen, 14.6°N, 42, 8°E) even 32.5°C. The coldest region is East Antarctica, where in the center of the plateau the average annual temperatures are -50 ... ... 55 C. 1

3. January (map XII). On the maps for January and July (the central months of winter and summer), the deviations of isotherms from the zonal direction are much larger. True, in the tropics of the northern hemisphere, the January temperatures on the oceans and continents are quite close to each other (under each given parallel). Isotherms are not particularly strongly deviating from the latitudinal circles. Inside the tropics, the temperature varies little with latitude. But outside the tropics in the northern hemisphere, it quickly decreases towards the pole. Isotherms pass here very densely in comparison with the July map. In addition, we find over the cold continents of the northern hemisphere in extratropical latitudes pronounced deflections of isotherms in the direction to the south, and over warmer oceans - to the north: tongues of cold and heat.

Map XI. Distribution of mean annual air temperature at sea level (°C).

The deflection of the isotherms to the north over warm waters North Atlantic, over eastern part ocean, where the branch of the Gulf Stream passes - the Atlantic Current. We see here a vivid example of the influence of ocean currents on temperature distribution. The zero isotherm in this region of the North Atlantic penetrates beyond the Arctic Circle (in winter!). The sharp thickening of isotherms off the coast of Norway speaks of another factor - the influence of coastal mountains, behind which cold air accumulates in the depths of the peninsula. This enhances the contrast between temperatures over the Gulf Stream and the Scandinavian Peninsula. In the Pacific Coast region of North America, a similar influence of the Rocky Mountains can be seen. But the thickening of isotherms on the east coast of Asia is associated mainly with the nature of atmospheric circulation: in January, warm air masses with Pacific Ocean almost never reach the mainland of Asia, and cold continental air masses quickly warm up over the ocean.

Over the northeast of Asia and over Greenland we even find closed isotherms delineating islands of cold. In the first region, between Lena and Indigirka, the average January temperatures reach -48°C, and at the level of the area -50°C and below, the absolute minimums are even -70°C. This is the region of the Yakut pole of cold. The lowest temperatures are observed in Verkhoyansk (67.5°N, 133.4°E) and Oymyakon (63.2°N, 143.1°E).

Northeast Asia has very low temperatures throughout the troposphere in winter. But the occurrence of extremely low temperature minima near the earth's surface is facilitated in these areas by orographic conditions: these low temperatures are observed in depressions or valleys surrounded by mountains, where air stagnation is created in the lower layers.

The second cold pole in the northern hemisphere is Greenland. The average January temperature at the local level here drops to -55 ° C, and the lowest temperatures in the center of the island apparently reach the same low values ​​as in Yakutia (-70 ° C). On the map of isotherms for sea level, this Greenlandic the cold pole is not as well pronounced as the Yakut one, due to the high altitude of the Greenland plateau. The essential difference between the Greenland pole of cold and the Yakut one is that in summer the temperatures over the ice of Greenland are very low: average temperature July at the level of the terrain up to - 15 ° С. In Yakutia, on the other hand, summer temperatures are relatively high: of the same order as under the corresponding latitudes in Europe. Therefore, the Greenland pole of cold is permanent, and the Yakut one is only winter. The area of ​​Baffin Island is also very cold.

Map XII. Distribution of mean monthly air temperature at sea level in January (°C).

In the region of the North Pole, the average winter temperature is higher than in Yakutia and Greenland, since cyclones relatively often bring air masses here from the Atlantic and Pacific oceans.

January is summer in the southern hemisphere. The distribution of temperature in the tropics of the southern hemisphere over the oceans is very even. But over the continents South Africa, South America and especially in Australia well-defined heat islands with average temperatures up to 34 ° C in Australia are outlined. Maximum temperatures reach 55 °C in Australia. In South Africa, ground-level temperatures are not as high due to the high elevation of the ground above sea level: absolute temperature maxima do not exceed 45 °C.

In the extratropical latitudes of the southern hemisphere, the temperature drops more or less rapidly to about the 50th parallel. Then comes a wide zone with uniform temperatures close to 0-5 ° C, to the very coast of Antarctica. In the depths of the icy continent, the temperature drops to -35°C. Attention should be paid to tongues of cold over the oceans off the western coasts of South America and South Africa, associated with cold ocean currents.

4. July (Map XIII). In July, in the tropics and subtropics of the northern, now summer hemisphere, heat islands with closed isotherms over North Africa, Arabia, Central Asia and Mexico. It should be noted that both Mexico and Central Asia have high elevations above sea level, and temperatures at local level are not as high as at sea level.

Average July temperatures in the Sahara reach 40 ° C (slightly lower at the local level). The absolute maximum temperature in North Africa reaches 58 ° C (Azizia in the Libyan Desert, south of the city of Tripoli; 32.4 ° N, 13.0 ° E). A little lower, 57°C, is the absolute maximum temperature in a deep depression among the mountains in California, in the Valley

Map XIII. Distribution of mean monthly air temperature at sea level in July (°C).

Rice. 28. Dependence of the average air temperature near the earth's surface on the geographical latitude. 1 - January, 2 - July, 3 - year.

Deaths (36.5°N, 117.5°W). In the USSR, the absolute maximum temperature in Turkmenistan reaches 50 °C.

The air is colder over the oceans than over the continents, both in the tropics and in extratropical latitudes.

There are no islands of heat and cold with closed isotherms in the extratropical latitudes of the northern hemisphere, but the isotherm troughs are noticeable towards the equator over the oceans and towards the pole over the continents. We also see the deflection of isotherms to the south over Greenland with its permanent ice cover. The low temperatures over Greenland are, of course, better expressed at the level of the area, where the average temperature in the center of the island is below -15 °C.

The concentration of isotherms off the coast of California is interesting, associated with the proximity of overheated deserts and the cold California Current. The average July temperature on the coast of Northern California is about 16 ° C, and in the desert inland up to 32 ° C and above. It should also be noted tongues of cold over the Sea of ​​Okhotsk and the Bering Sea and over Baikal. The temperature over the latter in July is lower by about 5°C compared to the areas 100 km away from the lake.

In the southern hemisphere, it is winter in July and there are no closed isotherms over the continents. The influence of cold currents off the western coasts of America and Africa is also felt in July (tongues of cold). But in general, isotherms are especially close to latitudinal circles. In extratropical latitudes, the temperature decreases quite rapidly towards Antarctica. On the outskirts of the mainland, it reaches -15 ... -35 °С, and in the center of East Antarctica, the average temperatures are close to -70 °С. In some cases, temperatures below -80 °C are observed, the absolute minimum is below -88 °C (Vostok station, 72.1 ° S, 96.6 ° E, altitude 3420 m). This is the pole of cold not only of the southern hemisphere, but of the entire globe.

The terrain also affects the air temperature. With height, the air temperature decreases (by 0.6ºC for every 100 m), so mountainous and flat areas located along the same latitude have unequal average air temperatures. It is much lower in the mountains. (see fig. 2).

Rice. 2. Decrease in temperature with height

Summer is coldest in the Far North. On some islands in the Arctic Ocean, the average temperature of the warmest month is 0ºC.

The most heat air in July (+45ºC), with an average of +24ºC (as at the equator), registered at Caspian lowland, in the area of ​​the famous salt lakes Elton and Baskunchak. This area is located in the south of our country, and in the summer it is characterized by a high angle of incidence of sunlight. Low air humidity and cloudless skies increase the proportion of direct radiation. Cool winds from the Atlantic do not reach the territory, but sultry and dry winds from Central Asia often blow, bringing continental tropical air masses. At this time, the highest air temperatures are observed (See Fig. 3).

Rice. 3. Factors shaping the climate of the Caspian lowland

The distribution of temperatures in January is decisively influenced by the circulation of the atmosphere, i.e., the movement air masses. Warm in winter time the air of the Atlantic does not allow the European part of the country to cool. January isotherms in most of the territory of Russia have not sublatitudinal, but submeridional strike: the closer to the Atlantic Ocean, the warmer. In Rostov-on-Don, the average January temperatures are -4…-8ºC, in Moscow -8…-12ºC; in Omsk and Yekaterinburg -16…-20º C; in Irkutsk -24… -32º C; in Yakutsk below -40ºC (see Fig. 4).

Rice. 4. Average January temperatures in Russia ()

The lowest temperatures are typical for the north-east of Siberia. This territory is removed from the Atlantic, and separated from the Pacific Ocean by mountains. In addition, the penetration of the Pacific air is hindered by the dominance here in winter of high atmospheric pressure. The "poles of cold" of the Northern Hemisphere of the Earth are considered the villages of Verkhoyansk and Oymyakon (See Fig. 5).

Rice. 5. Verkhoyansk and Oymyakon - cold poles of the northern hemisphere

At the end of the XIX century. (1892) the lowest air temperature was recorded in Verkhoyansk: -69ºC. No observations were made in Oymyakon that year. However, in other years, it was noted that on the coldest nights, the air temperature in Oymyakon is about 2ºC lower than in Verkhoyansk. Based on this, it was considered that the absolute minimum temperature is typical for Oymyakon and is 71ºC. Only icy Antarctica competes with the North-East of Siberia. The absolute minimum air temperature on Earth was recorded at Vostok station - -89.2ºC (July 21, 1983) (See Fig. 6).

Rice. 6. Station "Vostok"

Abnormally low air temperatures in this area are due to the combined effect of all climate-forming factors. The territory is located in the area of ​​the Arctic Circle and receives little solar heat. The clear sky due to the high atmospheric pressure contributes to additional cooling. Both points are located in intermountain basins, where cold air stagnates. The spatial and temporal coincidence of all conditions led to the formation of the "pole of cold" of the northern hemisphere (See Fig. 7).

Rice. 7. Factors that shape the climate of the north-east of Siberia

The distribution of precipitation is mainly influenced by circulation processes and topography. Most of the moisture in the territory of Russia is brought by cyclones of the Atlantic Ocean. Due to the westerly winds and the absence of mountain barriers, they penetrate far to the east. Wet "breath" of the Atlantic is felt right up to the Yenisei. From west to east, the amount of precipitation gradually decreases. In St. Petersburg and the Moscow region, the annual amount of precipitation is more than 650 mm; in Samara - no more than 500 mm; in Yakutsk - about 350 mm; and in Verkhoyansk - 128 mm (less than in Baghdad, surrounded by deserts).

Rice. 8. Annual rainfall ()

The largest amount of precipitation is characteristic of the windward slopes of the mountains. This applies to the western slopes of the Urals, Altai, and especially the Greater Caucasus. Much less moisture is brought in from the Pacific Ocean. The deep penetration of the Pacific air masses is hindered by the western transport, which prevails in temperate latitudes, and, in addition, by the nature of the relief.

Air masses from the Arctic Ocean can penetrate far south. But it is cold, which means dry air. In addition, when moving south, the northern air masses warm up, and their relative humidity becomes even lower - in the summer, the penetration of air from the Arctic Ocean to the south causes droughts.

Along with the amount of precipitation, no less important climatic feature is their mode, i.e., distribution over the seasons of the year. Over most of the territory of our country, precipitation is unevenly distributed: most of it falls on the warm season, that is, in the summer. The summer maximum precipitation is more clearly expressed in the Asian part of the country. This is due to the low amount of precipitation in winter due to the dominance of the region of high atmospheric pressure. (see fig. 9).

Rice. 9. Precipitation of the warm period ()

The summer maximum precipitation is most pronounced in Primorye (Vladivostok); the amount of summer precipitation here is approximately equal to the sum of precipitation for the rest of the seasons.

The eastern coast of Kamchatka and the western slopes are characterized by a relatively uniform distribution of moisture over the seasons. Caucasus mountains. In any of the seasons, at least 200 mm of moisture falls here. These are not only the wettest, but also the snowiest areas of the country.

The place with the maximum annual precipitation is the windward slopes of the Achishkho ridge near Sochi (the western slope of the Greater Caucasus), where the annual precipitation is 3240 mm. Humid air is brought by the Black Sea cyclones. Encountering mountain slopes on its way, the air rises and cools, which contributes to precipitation. These processes take place all year round regardless of the seasons, which leads to a relatively uniform distribution of atmospheric moisture throughout the year.

Rice. 10. Achishkho Ridge ()

The driest places in Russia are the intermountain basins of Altai (Chuya steppe) and Sayan (Ubsunur basin). The annual precipitation here barely exceeds 100 mm. Humid air does not reach the inner parts of the mountains. Moreover, descending along the slopes into the basins, the air heats up and dries out even more. (see fig. 11 and fig. 12).

Rice. 11. Chui steppe ()

Rice. 12. Ubsunur hollow ()

Note that places with both minimum and maximum precipitation are located in the mountains. At the same time, the maximum amount of precipitation falls on the windward slopes. mountain systems, and the minimum - in the intermountain basins.

Is 300 mm of precipitation a lot or a little? It is impossible to answer this question unambiguously. This amount of precipitation is typical, for example, for both the northern and southern parts of the West Siberian Plain. At the same time, in the north, the territory is clearly waterlogged, as evidenced by severe waterlogging; and in the south, dry steppes are common - a manifestation of moisture deficiency. Thus, with the same amount of precipitation, the moistening conditions turn out to be fundamentally different.

In order to assess whether the climate in a given place is dry or humid, it is necessary to take into account not only the annual rainfall, but also evaporation.

Evaporation- the amount of moisture that could evaporate under given temperature conditions. Like precipitation, evaporation is measured in millimetres.

At the same time, the amount of precipitation does not depend on the amount of evaporation. It is determined by the amount of heat that the area receives. The higher the air temperature, the more moisture can evaporate.

Lines connecting points on the map with the same volatility have a latitudinal strike. Evaporation can be greater than, equal to or less than precipitation (see fig. 13).

Rice. 13. Evaporation and evaporation ()

The ratio of annual precipitation to evaporation is called moisture coefficient:

K= O/I

K - moisture coefficient

O - annual rainfall

I - evaporation

If K > 1 - excessive moisture (tundra, taiga, forests).

If K = 1 - sufficient moisture (forest-steppe and steppe).

If K< 1 - увлажнение недостаточное (полупустыня).

If K< < - увлажнение скудное (пустыня).

Moisture coefficient is the main characteristic of the moisture supply of the territory. It largely determines the features of such natural ingredients like surface water, land cover, wildlife.

Bibliography

1. Geography of Russia. Nature. Population. 1 hour Grade 8 / V.P. Dronov, I.I. Barinova, V.Ya Rom, A.A. Lobzhanidze.
2. V.B. Pyatunin, E.A. Customs. Geography of Russia. Nature. Population. 8th grade.
3. Atlas. Geography of Russia. population and economy. - M.: Bustard, 2012.
4. V.P. Dronov, L.E. Savelyeva. UMK (educational-methodical set) "SPHERES". Textbook “Russia: nature, population, economy. 8th grade". Atlas.

1. No. 3. Distribution of heat and moisture on the territory of Russia. ()
2. Climate-forming factors and atmospheric circulation ()
3. monthly climate data for Russian cities ()
4. The temperature in Russia is growing 2.5 times faster than in the rest of the world ()
5. New records of negative temperatures recorded in many regions of Russia ()
6. Temperature maps with region selection ()
7. Precipitation maps with region selection ()

Homework

1. What patterns of heat and moisture exist on the territory of our country?
2. How is the moisture coefficient determined and why is this indicator so important?
3. Using the maps of the atlas, fill in the table:

1. What is the power of the atmosphere and what gases form it?

Power conditionally 1000 km. Gases: nitrogen, oxygen, argon, carbon dioxide, neon, helium, methane, krypton, hydrogen, xenon.

2. What are the layers of the atmosphere?

The Earth's atmosphere consists of four layers: troposphere, stratosphere, mesosphere, ionosphere (thermosphere).

3. How are the average monthly and average annual temperatures of the Earth determined?

The monthly mean temperature is the arithmetic mean of the temperatures of each day, and the mean annual temperature is the arithmetic mean of the monthly mean temperature.

4. What conditions are necessary for education precipitation? Can cold air hold a lot of moisture? What kind of air is called saturated with water vapor?

The main condition for the formation of precipitation is the cooling of warm air, leading to the condensation of the vapor contained in it. The moisture content of the air depends on atmospheric pressure. Cold air, descending, cannot contain much moisture; when lowering, it compresses and heats up, due to which it moves away from the state of saturation and becomes drier. Therefore, in areas of high pressure over the tropics and near the poles, there is little precipitation. Air saturated with water vapor is air in which the vapor content is above 75%.

5. What is atmospheric pressure? How does it affect the weather in your area?

Atmospheric pressure - the pressure of the atmosphere on all objects in it and the Earth's surface. It affects the fact that we are in a zone with low pressure and because of this there is precipitation in the Urals.

6. What influence does wind direction and air masses have on the weather in your area?

The direction of the wind and air masses have a significant influence on the weather in our area, since they are constantly in motion and carry heat and cold, moisture and dryness from one latitude to another, from the oceans to the continents and from the continents to the oceans. The nature of the weather is determined by the downward and upward movement of air.

7. Determine: a) which isotherms cross the meridian 80 z. d.; b) what are the annual temperatures in the tropical, temperate, polar zones of illumination?

a) Isotherms –10°С, 0°С, +10°С, +20°С cross the meridian 80 W. e. b) In the tropical zone of illumination, the annual temperature is + 20 ° С, in temperate zones The annual temperature ranges from +20°С to –10°С, in the polar zones of illumination the annual temperature is below –10°С.

8. What pattern does the map data confirm?

The amount of heat received by the Earth decreases from the equator.

9. Using climatic maps, determine: a) which isotherms of annual temperatures cross the 40th meridian. d.; b) the average annual temperature in southern Africa; c) the annual amount of precipitation in the Sahara, in the region of Moscow, in the Amazon basin.

Isotherms –10°С, 0°С, +10°С, +20°С cross the 40th century meridian. d.; b) the average annual temperature in southern Africa is +20°C; c) annual precipitation in the Sahara - 76 mm, in the Moscow area - 650 mm, in the Amazon River basin - up to 3000 mm.

10. By climate map Australia define: average temperatures of January and July; annual precipitation in the west and east of the mainland; prevailing winds.

The average January temperature in Australia ranges from +20 C to +27 C; average temperature in July +14 C - +18 C; in the west 250 mm, in the east 2,000 mm; prevailing westerly winds.

Questions and tasks

1. Name main reason temperature distribution on the earth's surface.

The closer to the equator, the greater the angle of incidence of the sun's rays, which means that the earth's surface heats up more, which contributes to an increase in the temperature of the surface layer of the atmosphere.

2. What can be learned from climate maps?

Temperature distribution, annual precipitation, prevailing winds.

3. Why is there a lot of precipitation near the equator, and in tropical areas- few?

The main reason is the movement of air, which depends on the belts of atmospheric pressure and the rotation of the Earth around its axis. In areas of high pressure over the tropics and near the poles, there is little precipitation. A lot of precipitation falls in areas where there is low atmospheric pressure.

4. Name constant winds and explain their education. How can winds be grouped?

The trade winds blow in equatorial belt, since low pressure prevails there, and high pressure near the thirtieth latitudes, then at the Earth's surface the winds blow from the high pressure belts to the equator. West winds blow from tropical belts high pressure towards the poles, since 65 s. and yu. sh. low pressure prevails. However, due to the rotation of the Earth, they gradually deviate to the east and create an air flow from west to east.

5. What is an air mass?

An air mass is a large volume of air in the troposphere that has uniform properties.

6. What is the role of air currents in the distribution of heat and moisture on the Earth's surface?

Constant winds carry air masses from one area on the surface of the Earth to another. The weather depends on what air mass enters a particular area, and ultimately the climate of the area. Each air mass has its own individual properties: humidity, temperature, transparency, density.

7. People of what professions are engaged in the study of the atmosphere and the processes occurring within it?

Meteorologists, weather forecasters, climatologists, ecologists.

Temperature is a very variable characteristic of the atmosphere, it varies in time and space. Changes in temperature over time are associated with the daily course of the radiation balance, but the temperature also changes during the day due to the action of other factors, for example, advection of air masses, which causes non-periodic changes in air temperature.

There are certain and significant differences in the heating of the surface layers of soil and water, which affect the daily temperature course, as well as the seasonal course. So, the surface of the water heats up relatively little, but a thick layer of water warms up. The surface of the soil heats up very strongly, but heat is transferred deep into the soil weakly. As a result, the ocean gives off a lot of heat at night, while the soil surface cools very quickly.

These differences are also reflected in the seasonal course of surface temperature. However seasonal changes temperatures are caused mainly by the change of seasons, which is especially evident in the temperate and polar zones. At the same time, during the cold season, the water constantly gives off the accumulated heat (whereas the soil does not store so much heat), therefore, in the cold season, over the ocean, as well as over areas subject to its direct influence, it is warmer than over land not subject to the influence of the sea. air.

Considering maps of the long-term average distribution of air temperature at sea level for individual calendar months and for the entire year, we find a number of patterns in this distribution that indicate the influence of geographical factors. This is primarily the effect of latitude. The temperature generally decreases from the equator to the poles in accordance with the distribution of the radiation balance of the earth's surface. This decrease is especially significant in each hemisphere in winter, because near the equator the temperature varies little in the annual course, while at high latitudes it is much lower in winter than in summer.

However, the isotherms on the maps do not quite coincide with the latitudinal circles, as well as the isolines of the radiation balance (Fig. 6.8). They deviate especially strongly from zoning in the northern hemisphere. This clearly shows the influence of the division of the earth's surface into land and sea. In addition, perturbations in the temperature distribution are associated with the presence of snow or ice cover, mountain ranges, and ocean currents. Finally, the characteristics of the atmospheric circulation also affect the temperature distribution. After all, the temperature in each given place is determined not only by the conditions of the radiation balance in this place, but also by the transfer of air from other areas. For example, the lowest temperatures in Eurasia are not found in the center of the continent, but are strongly shifted to its eastern part. In the western part of Eurasia, temperatures are higher in winter and lower in summer than in the eastern part, precisely because, with the prevailing westerly direction of air currents, masses of sea air from the Atlantic Ocean penetrate far into Eurasia from the west.

Deviations from latitudinal circles are the smallest on the map of mean annual temperatures for sea level. In winter, the continents are colder than the oceans, and warmer in summer; therefore, in the average annual values, the opposite deviations of the isotherms from the zonal distribution are partially mutually compensated. On the average annual map, we find on both sides of the equator in the tropics a wide zone where the average annual temperatures are above 25 ° C. Within this zone, heat islands are outlined over North Africa and, less significant in size, over India and Mexico, where the average annual temperature is above 28°C. There are no such heat islands over South America, South Africa, and Australia; however, over these continents, the isotherms bend to the south, forming "heat tongues": high temperatures spread here further towards high latitudes than over the oceans. Thus, in the tropics, on average, the continents are warmer than the oceans (we are talking about the air temperature above them).

At extratropical latitudes, isotherms deviate less from latitudinal circles, especially in the southern hemisphere, where the underlying surface at middle latitudes is an almost continuous ocean. But in the northern hemisphere we still find in the middle and high latitudes more or less noticeable deviations of the isotherms to the south over the continents of Asia and North America. This means that, on an average annual basis, the continents in these latitudes are somewhat colder than the oceans.

Fig.6.8. Distribution average annual temperature air at sea level

The features of the temperature distribution in January and July also differ significantly (these months are usually used in climatology as a characteristic of winter and summer). Such maps are shown in Figures 6.9 and 6.10.

January is winter in the northern hemisphere. The deviations of the isotherms from the zonal direction are significant. Inside the tropics, the temperature varies little with latitude. But outside the tropics in the northern hemisphere, it quickly decreases towards the pole. Isotherms pass here very densely in comparison with the July map. In addition, we find over the cold continents of the northern hemisphere in extratropical latitudes pronounced deflections of isotherms in the direction to the south, and over warmer oceans - to the north: tongues of cold and heat.

Especially significant is the deflection of isotherms to the north over the warm waters of the North Atlantic, over the eastern part of the ocean, where the branch of the Gulf Stream passes - the Atlantic Current. We see here a vivid example of the influence of ocean currents on temperature distribution. The zero isotherm in this region of the North Atlantic penetrates even beyond the Arctic Circle (in winter!). The sharp thickening of isotherms off the coast of Norway speaks of another factor - the influence of coastal mountains, behind which cold air accumulates in the depths of the peninsula.

Fig.6.9. Distribution of mean monthly air temperature at sea level in January

Fig.6.10. Distribution of mean monthly air temperature at sea level in July

This enhances the contrast between temperatures over the Gulf Stream and the Scandinavian Peninsula. In the Pacific Coast region of North America, a similar influence of the Rocky Mountains can be seen. But the thickening of isotherms on the east coast of Asia is mainly due to the nature of atmospheric circulation: in January, warm air masses from the Pacific Ocean almost do not reach the Asian mainland, and cold continental air masses quickly warm up over the ocean. Over the northeast of Asia and over Greenland we even find closed isotherms, delineating a kind of islands of cold. In the first region, between Lena and Indigirka, the average January temperatures reach -50°C, this is the region of the Yakut pole of cold. Greenland is the second cold pole in the northern hemisphere. The average January temperature at the local level here drops to -55 ° C, and the lowest temperatures in the center of the island apparently reach the same low values ​​as in Yakutia. In the region of the North Pole, the average winter temperature is higher than in Yakutia and Greenland, since cyclones relatively often bring air masses here from the Atlantic and Pacific oceans.

January is summer in the southern hemisphere. The distribution of temperature in the tropics of the southern hemisphere over the oceans is very even. But over the continents in South Africa, South America and especially in Australia, well-defined heat islands are outlined with average temperatures up to 34 ° C in Australia. Maximum temperatures reach 55 °C in Australia. In South Africa, ground-level temperatures are not as high due to the high elevation of the ground above sea level: absolute temperature maxima do not exceed 45 °C.

In the extratropical latitudes of the southern hemisphere, the temperature drops more or less rapidly to about the 50th parallel. Then comes a wide zone with uniform temperatures close to 0 °C, all the way to the shores of Antarctica. In the depths of the icy continent, the temperature drops to -35°C.

July is summer in the northern hemisphere. In July, in the tropics and subtropics of the northern, summer hemisphere, heat islands with closed isotherms over North Africa, Arabia, Central Asia and Mexico are well expressed.

The air is colder over the oceans than over the continents, both in the tropics and in extratropical latitudes.

In the southern hemisphere, it is winter in July and there are no closed isotherms over the continents. The influence of cold currents off the western coasts of America and Africa is also felt in July (tongues of cold). But in general, isotherms are especially close to latitudinal circles. In extratropical latitudes, the temperature decreases quite rapidly towards Antarctica. In the center of East Antarctica, average temperatures are close to -70°C. In some cases, temperatures below -80°C are observed, the absolute minimum is below -88°C (Vostok station). This is the pole of cold not only of the southern hemisphere, but of the entire globe.

The difference between the average monthly temperatures of the warmest and coldest months is called the annual air temperature amplitude. In climatology, annual temperature amplitudes are considered, calculated from long-term average monthly temperatures.

The annual amplitude of air temperature primarily increases with geographic latitude. At the equator, the influx of solar radiation changes very little during the year; in the direction of the pole, the differences in the inflow of solar radiation between winter and summer increase, and at the same time, the annual amplitude of air temperature also increases. Over the ocean, far from the coast, this latitudinal change in the annual amplitude, however, is small.

Annual temperature amplitudes over land are much larger than over the sea (as well as daily amplitudes). Even over relatively small continental massifs of the southern hemisphere, they exceed 15°C, and under a latitude of 60° on the Asian mainland, in Yakutia, they reach 60°C (Fig. 6.11).

Fig.6.11 Distribution of the average annual air temperature amplitude

But small amplitudes are also observed in many areas over land, even far from the coastline, if air masses from the sea often come there, for example, in Western Europe. On the contrary, increased amplitudes are also observed over the ocean where air masses from the mainland often enter, for example, in the western parts of the oceans of the northern hemisphere. Therefore, the annual temperature amplitude depends not only on the nature of the underlying surface or on the proximity of a given place to the coastline. It depends on the frequency of air masses of marine and continental origin in a given place, i.e., on the conditions of the general circulation of the atmosphere.

Not only the seas, but also large lakes reduce the annual amplitude of air temperature and thereby soften the climate. In the middle of Lake Baikal, the annual amplitude of air temperature is 30 - 31 ° C, on its shores it is about 36 ° C, and under the same latitude on the river. Yenisei 42 °C.

Usually, the climate over the sea, characterized by small annual temperature amplitudes, is called maritime climate , and the climate over land with large annual temperature amplitudes - continental. The continentality of the climate should always be kept in mind, especially when considering climatic characteristic terrain. So, Western Europe characterized by a pronounced maritime climate (the influence of the air masses of the Atlantic). Siberia, on the other hand, continental climate. Sometimes, to characterize continentality, the so-called. continental indexes.

Question 1. What determines the distribution of heat over the surface of the Earth?

The distribution of air temperature above the Earth's surface depends on the following four main factors: 1) latitude, 2) height of the land surface, 3) type of surface, especially the location of land and sea, 4) heat transfer by winds and currents.

Question 2. In what units is temperature measured?

In meteorology and in everyday life, the Celsius scale or degrees Celsius is used as a unit of temperature.

Question 3. What is the name of the temperature measuring device?

Thermometer - a device for measuring air temperature.

Question 4. How does the air temperature change during the day, during the year?

The change in temperature depends on the rotation of the Earth around its axis and, accordingly, on changes in the amount of solar heat. Therefore, the air temperature rises or falls depending on the location of the Sun in the sky. The change in air temperature during the year depends on the position of the Earth in its orbit as it revolves around the Sun. In summer, the earth's surface heats up well due to direct sunlight.

Question 5. Under what conditions at a particular point on the surface of the Earth will the air temperature always remain constant?

If the Earth does not rotate around the sun and its axis, and there will be no air transport by winds.

Question 6. According to what pattern does air temperature change with height?

When rising above the Earth's surface, the air temperature in the troposphere drops by 6 C for each kilometer of ascent.

Question 7. What is the relationship between air temperature and the geographical latitude of the place?

The amount of light and heat received earth's surface, gradually decreases in the direction from the equator to the poles due to a change in the angle of incidence of the sun's rays.

Question 8. How and why does the air temperature change during the day?

The sun rises in the east, rises higher and higher, and then begins to sink until it sets below the horizon until the next morning. The daily rotation of the Earth causes the angle of incidence of the sun's rays on the Earth's surface to change. This means that the level of heating of this surface also changes. In turn, the air, which is heated from the Earth's surface, receives a different amount of heat during the day. And at night, the amount of heat received by the atmosphere is even less. This is the reason for the diurnal variability. During the day, the air temperature rises from dawn to two in the afternoon, and then begins to drop and reaches a minimum an hour before dawn.

Question 9. What is the temperature range?

The difference between the highest and lowest air temperature for any period of time is called the temperature amplitude.

Question 11. Why is the highest temperature observed at 2 p.m., and the lowest - in the "pre-dawn hour"?

Because at 14 o'clock the Sun heats the earth as much as possible, and in the pre-dawn hour the Sun has not yet risen, and during the night the temperature dropped all the time.

Question 12. Is it always possible to limit ourselves to knowledge only about average temperatures?

No, because in certain situations it is necessary to know the exact temperature.

Question 13. For what latitudes and why are the lowest average air temperatures typical?

For polar latitudes, since Sun rays reach the surface at the smallest angle.

Question 14. For what latitudes and why are the highest average air temperatures typical?

The highest average air temperatures are typical for the tropics and the equator, since there is the largest angle of incidence of sunlight.

Question 15. Why does the air temperature decrease with height?

Because the air warms up from the surface of the Earth, when it has a positive temperature and it turns out that the higher the air layer, the less it warms up.

Question 16. What do you think, which month of the year is characterized by the minimum average air temperatures in the Northern Hemisphere? In the southern hemisphere?

January is, on average, the coldest month of the year in most of the Earth's Northern Hemisphere, and the warmest month of the year in most of the Southern Hemisphere. June is, on average, the coldest month of the year in most of the Southern Hemisphere.

Question 17 latitude, 50°S sh., 80 p. sh.?

Question 18. Determine the air temperature at a height of 3 km, if it is +24 ° C at the Earth's surface?

tn=24-6.5*3=4.5 ºС

Question 19. Calculate the average temperature value according to the data presented in the table.

(5+0+3+4+7+10+5) : 6 = 4,86; (-3 + -1) : 2 = -2; 4,86 - 2 = 2,86

Answer: average temperature = 2.86 degrees.

Question 20. Using the tabular data given in task 2, determine the temperature amplitude for the specified period.

The temperature amplitude for the specified period will be 13 degrees.