Atmosphere temperature distribution over the earth's surface. Earth surface temperature

I am used to the climate in which I live, but still in the summer I want maximum warmth, and therefore I am going to the south of the country. In winter, I admire the beauty of snow-covered nature. In fact, the temperature in different regions of the country is very different. If in winter it snows almost everywhere, then in summer, if you move from north to south, the weather changes.

What factors determine the temperature distribution

If we take the entire territory of Russia, then even in regions that are located in the same latitudes, the climate can be very different. Here are the main reasons that affect the temperature distribution on the surface:

• relief features;
• proximity to or distance from the sea;
• circulation of air masses;
• distance from the equator.

I will give a few examples. Ural mountains retain moist air masses that are directed from the sea, so the climate in Siberia is continental. It has hot but short summers and harsh and long winters.

The sea on one side and the mountains on the other are the main factors that determine the subtropical climate in the south of the Krasnodar Territory.

In general, the climate is milder up to the Urals than to the east of these mountains.

How is the temperature distributed in Russia in summer and winter

Russia is characterized by a clear division of the year into different, pronounced seasons, as well as a large temperature difference.

Generally speaking, the temperature is distributed unevenly. Of course, if you move from south to north, the average annual or monthly temperature drops. If in the south it is hot and sunny all summer, then in the north there are only a few warm days.

For example, in Siberia, the temperature range is the largest in the country, because in summer it can be up to +40, and in winter the same amount, but with a minus sign. In the north, at the beginning of summer, the thermometer can drop below zero, while in the south they are already swimming in the sea with might and main.

Snow falls almost throughout the country in winter, and only in the south the climate is milder. The harshest climate in the north Far East, there average temperature January is -46 degrees Celsius.

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, affecting daily course temperature, 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 temperature changes 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 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 of mean annual air temperature 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 cold continents 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 temperature in winter 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 coastline if air masses often come there from the sea, 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 western parts 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 sea, but also big 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). And Siberia, on the contrary, has a continental climate. Sometimes, to characterize continentality, the so-called. continental indexes.

The temperature of the Earth's surface reflects the heating of the air in any particular area of ​​​​our planet.

As a rule, special devices are used to measure it - thermometers located in small booths. Air temperature is measured at least 2 meters above the ground.

Average surface temperature of the Earth

Under the average temperature of the Earth's surface, they mean the number of degrees not in any particular place, but the average figure from all points of our globe. For example, if in Moscow the air temperature is 30 degrees, and in St. Petersburg 20, then the average temperature in the region of these two cities will be 25 degrees.

(Satellite image of the temperature of the Earth's surface in the month of January with a scale of Kelvin values)

When calculating the average temperature of the Earth, readings are taken not from a specific region, but from all regions of the globe. On this moment The average temperature of the Earth is +12 degrees Celsius.

Minimum and maximum

The lowest temperature was recorded in 2010 in Antarctica. The record was -93 degrees Celsius. The hottest point on the planet is the Deshte Lut desert, located in Iran, where the record temperature was + 70 degrees.

(average temperature for July )

Antarctica is traditionally considered the coldest place on Earth. Africa and North America are constantly competing for the right to be called the warmest continent. However, all other continents are also not so far away, lagging behind the leaders by only a few degrees.

Distribution of heat and light on Earth

Our planet receives most of its heat from a star called the Sun. Despite the rather impressive distance separating us, the reaching amount of radiation is more than enough for the inhabitants of the Earth.

(average temperature for January distributed over the surface of the earth)

As you know, the Earth constantly revolves around the Sun, which illuminates only one part of our planet. Hence the uneven distribution of heat over the planet. The Earth has an ellipsoidal shape, as a result of which the rays of the Sun fall on different parts of the Earth at different angles. This results in an imbalance in the distribution of heat on the planet.

Another important factor affecting the distribution of heat is the tilt of the earth's axis, along which the planet makes a complete revolution around the sun. This tilt is 66.5 degrees, so our planet is constantly facing the northern part towards the North Star.

It is thanks to this slope that we have seasonal and temporal changes, namely, the amount of light and heat, day or night, either increases or decreases, and summer is replaced by autumn.

During the day, the air temperature changes. The lowest temperature is observed before sunrise, the highest - at 14-15 hours.

To determine average daily temperature it is necessary to measure the temperature four times a day: at 1 am, at 7 am, at 1 pm, at 7 pm. The arithmetic mean of these measurements is the average daily temperature.

The air temperature changes not only during the day, but also throughout the year (Fig. 138).

Rice. 138. Head change in air temperature at a latitude of 62 ° N. latitude: 1 - Torshavn Denmark (marine tyne), average annual temperature 6.3 °C; 2- Yakutsk (continental type) - 10.7 °С

Average annual temperature is the arithmetic average of temperatures for all months of the year. It depends on the geographic latitude, the nature of the underlying surface, and the transfer of heat from low to high latitudes.

The Southern Hemisphere is generally colder than the Northern Hemisphere due to the ice and snow covered Antarctica.

The warmest month of the year in the Northern Hemisphere is July, while the coldest month is January.

Lines on maps connecting places with the same air temperature are called isotherms(from the Greek isos - equal and therme - heat). Their complex location can be judged from the maps of January, July and annual isotherms.

The climate at the corresponding parallels of the Northern Hemisphere is warmer than the corresponding parallels of the Southern Hemisphere.

The highest annual temperatures on Earth are observed on the so-called thermal equator. It does not coincide with the geographic equator and is located at 10 ° N. sh. This is due to the fact that in the Northern Hemisphere a large area is occupied by land, and in the Southern Hemisphere, on the contrary, there are oceans that spend heat on evaporation, and besides this, the influence of ice-covered Antarctica affects. The average annual temperature at the parallel is 10° N. sh. is 27 °C.

Isotherms do not coincide with parallels despite the fact that solar radiation is distributed zonally. They bend, moving from the mainland to the ocean, and vice versa. So, in the Northern Hemisphere in January over the mainland isotherms deviate to the south, and in July - to the north. This is due to the unequal conditions for heating land and water. In winter, land cools, and in summer it heats up faster than water.

If we analyze isotherms in the Southern Hemisphere, then in temperate latitudes their course is very close to parallels, since there is little land there.

In January the most heat air is observed at the equator - 27 ° C, in Australia, South America, central and southern parts Africa. The lowest temperature in January was recorded in the northeast of Asia (Oymyakon, -71 °С) and at the North Pole -41 °С.

The "warmest parallel of July" is the parallel of 20°N. with a temperature of 28 ° C, and the coldest place in July is the south pole with an average monthly temperature of -48 ° C.

The absolute maximum air temperature was recorded in North America(+58.1 °С). The absolute minimum air temperature (-89.2 °C) was recorded at the Vostok station in Antarctica.

Observations revealed the existence of daily and annual fluctuations in air temperature. The difference between the largest and the smallest values air temperature during the day is called daily range, and during the year annual temperature range.

The daily temperature amplitude depends on a number of factors:

• latitude of the area - decreases when moving from low to high latitudes;
• the nature of the underlying surface - it is higher on land than over the ocean: over the oceans and seas, the daily temperature amplitude is only 1-2 ° C, and over the steppes and deserts it reaches 15-20 ° C, since the water heats up and cools down more slowly than land ; in addition, it increases in areas with bare soil;
• terrain - due to lowering into the valley of cold air from the slopes;
• cloud cover - with its increase, the daily temperature amplitude decreases, since clouds do not allow the earth's surface to become very hot during the day and cool at night.

The magnitude of the daily amplitude of air temperature is one of the indicators of the continentality of the climate: in deserts, its value is much greater than in areas with a maritime climate.

Annual temperature amplitude has patterns similar to the daily temperature amplitude. It depends mainly on the latitude of the area and the proximity of the ocean. Over the oceans, the annual temperature amplitude most often does not exceed 5-10 °C, and over the interior regions of Eurasia - up to 50-60 °C. Near the equator, average monthly air temperatures differ little from each other throughout the year. At higher latitudes, the annual temperature amplitude increases, and in the Moscow region it is 29 °C. At the same latitude, the annual temperature amplitude increases with distance from the ocean. In the equatorial zone above the ocean, the annual temperature amplitude is only G, and over the continents - 5-10 °.

The different conditions for heating water and land are explained by the fact that the heat capacity of water is twice that of land, and with the same amount of heat, land heats up twice as fast as water. On cooling, the opposite happens. In addition, when heated, water evaporates, while a significant amount of heat is consumed. It is also important that on land heat is distributed practically only in the upper soil layer, and only a small part of it is transferred to the depth. In the seas and oceans, a considerable thickness is being heated. This is facilitated by vertical mixing of water. As a result, oceans accumulate heat much more than land, retain it longer and spend it more evenly than land. The oceans heat up more slowly and cool more slowly.

The annual temperature amplitude in the Northern Hemisphere is 14 °С, and in the Southern - 7 °С. For the globe, the average annual air temperature near the earth's surface is 14 °C.

Thermal belts

The uneven distribution of heat on the Earth, depending on the latitude of the place, allows us to distinguish the following thermal belts, whose boundaries are isotherms (Fig. 139):

• the tropical (hot) zone is located between the annual isotherms + 20 °С;
• temperate zones of the Northern and Southern hemispheres - between the annual isotherms +20 °С and the isotherm of the warmest month +10 °С;
• the polar (cold) belts of both hemispheres are located between the isotherms of the warmest month +10 °С and О °С;
• the belts of eternal frost are limited by the 0°C isotherm of the warmest month. This is the realm of eternal snow and ice.

Rice. 139. Thermal belts of the Earth

The figures relating to the average temperatures of the parallels, although they reveal some general patterns, have the disadvantage that they are related to mathematical lines on the surface of the globe.

You can get rid of this shortcoming by resorting to the study of isotherm maps. It will suffice for us to confine ourselves to an investigation of the isotherms for January and July, i.e., the months which in most places on land characterize the coldest and warmest seasons of the year. In this case, we will use isotherms that are not reduced to sea level.

If the surface of the globe were completely homogeneous (for example, covered with a continuous water shell) and air transport on Earth would occur only along latitude circles, all isotherms would be parallel to the equator. The location of isotherms, close to hypothetical, can be observed only in the southern hemisphere with its vast oceanic expanses. In most cases, the course of the isotherms is extremely whimsical, which indicates a violation of the hypothetical heating conditions.

What causes these violations? Mainly by the nature of the distribution of land and sea, the relief and the existence of constant or dominant cold and warm air and sea currents. As a result, some places turn out to be warmer than they should be according to their geographical latitude, while others are colder, i.e., positive and negative temperature anomalies are observed. The difference in the heating of the land and the sea is due, respectively, to their small and large heat capacity, due to which the land heats up faster and more strongly than the sea, but cools faster and deeper.

Considering the map of July isotherms, we see:

1. In the extratropical regions of both hemispheres, the isotherms over the continents noticeably bend to the north (compared to their course to the sea). For the northern hemisphere, this means that here the land is heated more than the sea, and for the southern hemisphere (where July is - winter month) - that it is colder than the sea. Over the oceans, the average temperature is below +26° everywhere, except for the areas adjacent to the Antilles (here it can be up to +28°), while over the continents there are also much higher temperatures.

2. The highest average July temperatures are found not over the equator, but in the desert region of the northern hemisphere: the hottest places at this time include California, the Sahara, Arabia, Iran and inland Asia. The main reason is that in July the Sun is at its zenith in the northern hemisphere in the belt between the 23rd and 18th parallels: it is here, as well as in neighboring latitudes, that the heating is greatest. The absence of a dense vegetation cover in the desert areas listed above and low cloudiness are also important: with a clear sky, bare soil heats up especially strongly.

High in July and absolute temperatures on land. In Algeria, the lower reaches of the Euphrates, Turkmenistan and some other places, in some years there are days in July when the thermometer shows more than 50 ° in the shade. In Death Valley (California) on July 10, 1913, the highest the globe July temperature: 56°.7.

3. The map also shows the influence of sea currents. It is natural to expect that in winter time the greatest bending of the isotherms will be due to warm currents, and in summer to cold ones, although both, since they are constant, affect the isotherms all year round. In the northern hemisphere, isotherms along the western coasts of California and Africa bulge southward, the result of the influence of the California and Canary cold currents. Oppositely directed bends of isotherms in the southern hemisphere along the western coasts of South America and Africa are the result of the influence of the cold currents of Peru and Bengal. All these currents carry their jets far towards the equator and greatly cool the air in the area of ​​the coasts washed by them, creating here negative temperature anomalies.

Turning now to the map of January isotherms, we see:

1. The influence of the California cold current and partly the Canary current has weakened (since it is winter in the northern hemisphere), while the Peruvian and Bengal currents are more pronounced (since it is summer in the southern hemisphere). On the other hand, in the northern parts of the Atlantic and Pacific oceans, a strong poleward bending of isotherms reflects an increase in the thermal role of warm currents - the Gulf Stream, the Kuro-Sio and the Aleutian.

2. In the extratropical regions of both hemispheres, the isotherms over the continents are curved to the south. Therefore, in the northern hemisphere, the land is colder than the sea, and vice versa in the southern hemisphere. In January, Greenland and northeast Asia are subjected to particularly strong cooling. The lowest air temperature ever observed on Earth was -68° (Verkhoyansk). In January, there are nowhere such low temperatures over the ocean as over land.

3. The area of ​​greatest heating is under the Tropic of Capricorn in central Australia, southern Africa and South America. During January, the solar zenith passes from 23 to 18 ° S. sh.

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