Geographic distribution of air temperature. Earth surface temperature

Heat circulation, one of the climate-forming processes, describes the processes of receiving, transferring, transferring and losing heat in the earth-atmosphere system. Features of heat exchange processes determine the temperature regime of the area. The thermal regime of the atmosphere is primarily due to the heat exchange between atmospheric air And environment. In this case, the environment is understood to mean outer space, neighboring masses, and especially the earth's surface. Of decisive importance for the thermal regime of the atmosphere is heat exchange with the earth's surface through molecular and turbulent heat conduction.

The distribution of air temperature around the globe depends on general conditions influx of solar radiation by latitudes ( influence of latitude), from the distribution of land and sea, which absorb radiation differently and heat up differently ( underlying surface effect), and from air currents that carry air from one area to another ( influence of atmospheric circulation).

As follows from Fig. 1.9, the smallest deviations from latitude circles on the map of average annual temperatures for sea level. In winter, the continents are colder than the oceans, in summer they are warmer, therefore, in the average annual values, the opposite deviations of the isotherms from the zonal distribution are partially mutually compensated. On the map of the average annual temperature on both sides of the equator - in the tropics there is a wide zone where the average annual temperatures are above +25 °C. Inside the zone, heat islands over North Africa, India and Mexico are outlined by closed isotherms, where the average annual temperature is above +28 °C. Above South America, South Africa and Australia have no heat islands. However, over these continents, the isotherms bend southward, forming "heat tongues" in which high temperatures spread further towards high latitudes than over the oceans. Thus, the tropics of the continents are warmer than the tropics of the oceans (we are talking about the average annual air temperature above them).

Rice. 1.9. Distribution of the average annual air temperature at sea level (ºС) (Khromov S.P., Petrosyants M.A., 2006)

In 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. In the Northern Hemisphere, at middle and high latitudes, there are more or less noticeable deviations of 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 distribution are observed 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) ) 32.5 °C. The coldest region is East Antarctica, where in the center of the plateau the average annual temperatures are about -50¸-55 °C (Climatology, 1989).

The temperature decreases from the equator to the poles in accordance with the distribution of the radiation balance earth's surface.

The isotherms on the maps do not completely coincide with the latitudinal circles, as well as the isolines of the radiation balance, i.e. are not zonal. They deviate especially strongly from zonality in the Northern Hemisphere, where the influence of the division of the earth's surface on land and sea is clearly visible. In addition, perturbations in the temperature distribution are associated with the presence of snow or ice cover, mountain ranges, warm and cold ocean currents.

Temperature distribution is also influenced by features general circulation atmosphere, since the temperature in each given place is determined not only by the conditions of the radiation balance in this place, but also by air advection from other regions. For example, 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.

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 by the 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 most heat observed at 14:00, 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 the sun's 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 on average, the most cold month years for most northern hemisphere Earth, 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.

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 most severe climate is in the north of the Far East, where the average January temperature is -46 degrees Celsius.

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; V) annual amount precipitation in the Sahara, near 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. What is the main reason for the 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, but little in tropical areas?

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 near the thirtieth latitudes it is high, then at the surface of the Earth the winds blow from the belts high pressure to the equator. Western winds blow from the tropical high pressure belts towards the poles, since at 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.

2.1. Geographical distribution of the temperature of the surface layer of the atmosphere

The distribution of temperature over large areas or over the entire globe can be represented using isotherm maps. Isotherms are lines that connect points on a map with the same air temperature in this moment or an average over a given period of time.

For comparability of observations made at different points, the measured temperature is adjusted to sea level. The need for this is due to the fact that the average air temperature decreases with height. Therefore, over the hills it is on average lower than in the adjacent valleys. The reduction of temperature to sea level is based on the fact that in the troposphere it decreases by an average of 0.6 ° C / 100 m.

Isotherms on maps, depending on the purpose of their construction, are drawn after 1, 2, 4, 5 ° C, and sometimes even after 10 ° C. To identify the nature at different times of the year, it is convenient to use the isotherms of the average monthly temperature of two months of the year: the coldest (January) and the warmest (July).

January isotherms (Fig. 2) do not coincide with latitude circles. They have various curves, most pronounced in the northern hemisphere, especially in the areas of transition from sea to land and vice versa. This is explained by the difference in air temperatures over water bodies and continents. In the southern hemisphere, where the water surface is dominated, the isotherms run more smoothly and have an almost latitudinal direction. Isotherms are denser in the northern hemisphere than in the southern. This is especially evident over the continents, where the temperature contrasts between individual regions are greater than over the oceans.

Rice. 2. January isotherms (°С)

Over the northern part of the Atlantic Ocean, the direction of the January isotherms approaches the meridional one. This is explained by the fact that here the warm current of the Gulf Stream, washing the western shores of Europe, affects the air temperature. Almost in the meridional direction in winter, isotherms also pass in the north of the European part of Russia. The temperature here decreases with distance from the ocean, that is, from west to east, to about 135 ° E. e. In the north of Yakutia, in the region of Verkhoyansk and Oymyakon, there is the so-called pole of cold, bordered by an isotherm of -50 ° C. On some days, the temperature here drops even lower: in Verkhoyansk it reached -68 ° C, and in Oymyakon an absolute minimum temperature was noted air in the northern hemisphere, equal to -71 ° C. The pole of cold in the Oymyakon region is due to physical and geographical factors: Oymyakon is located in a basin where cold air flows from the north. Here it stagnates, since its mixing in winter, in the absence of significant heating, is weakened.

The second cold pole in the northern hemisphere is Greenland, where the average monthly temperature of the coldest month reduced to sea level is -55 ° C. The minimum temperature here is approximately 70 ° C. The emergence of the Greenlandic cold pole is associated with a large albedo of the glacial plateau. Small pockets of cold on the maps of January isotherms are also observed over Scandinavia and Asia Minor. January is summer in the southern hemisphere. Therefore, hot spots are located over South America, Africa and Australia at this time.

The July isotherms (Fig. 3) in the northern hemisphere are much less frequent than the January isotherms, since the temperature contrasts between the pole and the equator are much smaller in summer than in winter. In summer, the air temperature over the continents is higher than over the oceans. Therefore, in the northern hemisphere over the continents, the isotherms bend to the north. Over North America, Africa and Asia, closed areas of heat are well expressed. Particular attention should be paid to the region in the Sahara, where the average temperature in July

Rice. 3. July isotherms (°С)

is 40 °С, and on some days it exceeds 50 °С. The absolute maximum temperature in North Africa is 58°C (south of Tripoli). The same temperature was noted in California, in Death Valley, where the terrain (high mountains and deep valleys) contributes to the rise in air temperature.

The highest mean annual temperatures are observed approximately along 10°N. sh. The line connecting the points with the maximum average annual temperatures, is called the thermal equator. In summer, the thermal equator shifts to 20°N. sh., and in winter it approaches 5-10 ° N. sh., i.e. always remains in the northern hemisphere. This is explained by the fact that in the northern hemisphere there are more continents that heat up more than the oceans of the southern hemisphere.

Winter in the southern hemisphere in July. The isotherms here run almost in the zonal direction, i.e., they coincide in direction with the parallels. In the high southern latitudes, the temperature drops sharply towards Antarctica. On the ice plateau of Antarctica, the lowest air temperatures are observed. On the coast of Antarctica, the average temperature in July varies from -15 to -35° C, and in the center of East Antarctica it reaches -70° C. On some days, the temperature here drops below -80° C. For example, at st. East, located at 78 ° S. sh., registered the lowest air temperature on the globe near the earth's surface, equal to -88.3 ° C. Thus, the area in which the station is located. The East is the pole of cold not only for the southern hemisphere, but for everything the globe. Such a strong cooling of the air here is explained by the fact that Art. Vostok is located on a plateau, at an altitude of 3420 m above sea level, where, with a weak wind during the polar night, a strong cooling of the air occurs.

2.2. Non-periodic changes in air temperature.
Continental climate

In extratropical latitudes, non-periodic changes in air temperature are so frequent and significant that daily course temperature is clearly manifested only during periods of relatively stable, slightly cloudy anticyclonic weather. The rest of the time it is obscured by non-periodic changes, which can be very intense. For example, cold snaps in winter, when the temperature at any time of the day can drop (in continental conditions) by 10-20 ° C within one hour.

In tropical latitudes, non-periodic temperature changes are less significant and do not disturb the diurnal temperature variation so much.

Non-periodic temperature changes are mainly associated with the advection of air masses from other regions of the Earth. Particularly significant cooling periods (sometimes called cold waves) occur in temperate latitudes due to the intrusions of cold air masses from the Arctic and Antarctica. In Europe, severe winter cooling also occurs when cold air masses penetrate from the east, and in Western Europe- With European territory Russia. Cold air masses sometimes penetrate the Mediterranean basin and even reach North Africa and Asia Minor. But more often they linger in front of the mountain ranges of Europe, located in a latitudinal direction, especially in front of the Alps and the Caucasus. That's why climatic conditions The Mediterranean basin and the Transcaucasus are significantly different from the conditions of close, but more northern regions.

In Asia, cold air freely penetrates to the mountain ranges that limit the territory of the Central Asian republics from the south and east, so winters in the Turan lowland are quite cold. But such mountain ranges as the Pamirs, Tien Shan, Altai, the Tibetan Plateau, not to mention the Himalayas, are obstacles to the further penetration of cold air masses to the south. In rare cases, significant advective cooling is observed, however, in India: in Punjab, on average, by 8 - 9 ° C, and in March 1911 the temperature dropped by 20 ° C. Cold masses flow around mountain ranges from the west. Easier and more often, cold air penetrates southeast Asia without encountering significant obstacles along the way.

There are no latitudinal mountain ranges in North America. Therefore, the cold masses of Arctic air can spread unhindered to Florida and the Gulf of Mexico.

Over the oceans, intrusions of cold air masses can penetrate deep into the tropics. Of course, cold air gradually warms up over warm water, but it can still cause noticeable temperature drops.

Intrusions of sea air from the mid-latitudes of the Atlantic Ocean into Europe create warming in winter and cooling in summer. The farther into the depths of Eurasia, the less the frequency of Atlantic air masses becomes and the more their initial properties change over the mainland. But still, the influence of invasions from the Atlantic on the climate can be traced all the way to the Central Siberian Plateau and Central Asia.

Tropical air invades Europe both in winter and in summer from North Africa and from the low latitudes of the Atlantic. In summer, air masses close in temperature to the air masses of the tropics and therefore also called tropical air form in the south of Europe or come to Europe from Kazakhstan and Central Asia. Tropical air intrusions from Mongolia, northern China, from the southern regions of Kazakhstan and from the deserts of Central Asia are observed in the Asian territory of Russia in summer.

In some cases, strong temperature rises (up to + 30 ° C) during summer intrusions of tropical air spread to the Far North of Russia.

IN North America tropical air invades from both the Pacific and Atlantic oceans, especially from the Gulf of Mexico. On the mainland itself, tropical air masses form over Mexico and the southern United States.

Even in the region of the North Pole, the air temperature sometimes rises to zero in winter as a result of advection from temperate latitudes, and warming can be traced throughout the troposphere.

Movements of air masses, leading to advective temperature changes, are associated with cyclonic activity.

On smaller spatial scales, abrupt non-periodic temperature changes can be associated with foehns in mountainous areas, i.e. with adiabatic heating of air during its downward movement.

Since non-periodic temperature changes occur differently every year, the average annual air temperature at each individual point in different years different. So, in Moscow in 1862 the average annual temperature was +1.2 ° C, in 1925 +6.1 ° C. The average temperature of a month in some years varies even more widely, especially for winter months. So, in Moscow for 170 years, the average temperature in January fluctuated within 19 ° С (from -21 to -2 ° С), and in July - within 7 ° С (from +15 to +22 ° С). But these are the extreme limits of fluctuations. On average, the temperature of one or another month of a particular year deviates from the long-term average for this month in winter by about 3 ° C and in summer by 1.5 ° C in one direction or another.

The deviation of the average monthly temperature from the climatic norm is called the anomaly of the average monthly temperature of a given month. The average long-term value of the absolute values ​​of monthly temperature anomalies can be taken as a measure of variability, which is the greater, the more intense the non-periodic temperature changes in a given area, giving the same month a different character in different years. Therefore, the variability of average monthly temperatures increases with latitude: in the tropics it is small, in temperate latitudes it is significant, in a maritime climate it is less than in the continental one. The variability is especially great in transitional areas between maritime and continental climates, where maritime air masses may prevail in some years, and continental in others.

Continental climate. The climate over the sea, characterized by small annual temperature amplitudes, is naturally called maritime, in contrast to the continental climate over land with large annual temperature amplitudes. The maritime climate also extends to the areas of the continents adjacent to the sea, over which the frequency of sea air masses is high. We can say that sea air brings a maritime climate to land. Areas of the oceans dominated by air masses from the nearby mainland have a continental rather than maritime climate.

The maritime climate is well expressed in Western Europe, where air transfer from the Atlantic Ocean dominates all year round. In the extreme west of Europe, annual air temperature amplitudes are only a few degrees. With distance from the Atlantic Ocean deep into the mainland, annual temperature amplitudes increase. In other words, the continentality of the climate is growing. IN Eastern Siberia annual amplitudes reach several tens of degrees. Summers here are hotter than in Western Europe, winters are much more severe. Proximity of Eastern Siberia to Pacific Ocean is of little importance, since due to the conditions of the general circulation of the atmosphere, air from this ocean does not penetrate far into Siberia, especially in winter. Just on Far East the influx of air masses from the ocean in summer lowers the temperature and thereby somewhat reduces the annual amplitude.

The continental climate is on average annual colder than the sea. This means that a large amplitude in the continental climate of temperate and high latitudes in comparison with the maritime climate is created not so much by an increase in summer temperatures as by a decrease in winter temperatures. In tropical latitudes, on the contrary, an increased amplitude over land is created not so much more cold winter how much more hot summer. Therefore, the average annual temperature in the tropics is higher in the continental climate than in the sea.

As we move deeper into Eurasia from west to east, the average temperatures of the warmest and coldest months, average annual temperatures and annual temperature amplitudes change as shown below (Table 1) for several places on the 52nd parallel:

Table 1.

Features of the distribution of average temperatures and annual air amplitudes depending on the continentality of the climate