Daily variation of air temperature at the earth's surface, thermal regime of the atmosphere, meteorology and climatology development of science, geographic factors of climate, climate measurement, climate prediction, weather prediction. Daily and annual course of tempera

General information about air temperature

Definition 1

The indicator of the thermal state of air recorded by measuring instruments is called temperature.

The sun's rays, falling on the spherical shape of the planet, heat it in different ways, because they come from different angles. The sun's rays do not heat the atmospheric air, while the earth's surface heats up very strongly and transfers thermal energy to the adjacent layers of air. Warm air becomes light and rises, where it mixes with cold air, giving off part of its thermal energy. Warm air cools with height and at a height of $10$ km its temperature becomes constant $-40$ degrees.

Definition 2

In the stratosphere, temperatures are shifting, and its indicators begin to rise. This phenomenon has been named temperature inversion.

Most of all, the surface of the earth heats up where the sun's rays fall at right angles - this is the area equator. The minimum amount of heat received polar and polar regions, because the angle of incidence of the sun's rays is sharp and the rays glide over the surface, and besides, they are also scattered by the atmosphere. As a result of this, we can say that the air temperature decreases from the equator to the poles of the planet.

An important role is played by the inclination of the earth's axis to the plane of the orbit and the time of year, which leads to uneven heating of the Northern and Southern hemispheres. Air temperature is not a constant indicator; it changes throughout the day anywhere in the world. On thematic climate maps, air temperature is shown by a special symbol, which is called isotherm.

Definition 3

Isotherms- these are lines connecting points on the earth's surface with the same temperature.

On the basis of isotherms, thermal belts are distinguished on the planet, going from the equator to the poles:

• Equatorial or hot belt;
• Two temperate belts;
• two cold zones.

Thus, the air temperature is greatly influenced by:

• Geographic latitude of the place;
• Heat transfer from low latitudes to high latitudes;
• Distribution of continents and oceans;
• Location of mountain ranges;
• Currents in the ocean.

Temperature change

The air temperature changes continuously throughout the day. The land heats up quickly during the day, and the air heats up from it, but with the onset of the night, the land also cools quickly, and after it the air cools. Therefore, it will be coolest in the predawn hours, and warmest in the afternoon.

The exchange of heat, mass and momentum between the individual layers of the atmosphere occurs constantly. The interaction of the atmosphere with the earth's surface is characterized by the same processes and is carried out in the following ways:

• Radiation path (air absorption of solar radiation);
• Thermal conduction path;
• Heat transfer by evaporation, condensation or crystallization of water vapor.

The air temperature even at the same latitude cannot be constant. On Earth, only in one climatic zone there is no daily temperature fluctuation - this is a hot or equatorial zone. Here, both night and day air temperatures will have the same value. On the coasts of large reservoirs and above their surface, the daily amplitude is also insignificant, but in the desert climate zone, the difference between day and night temperatures sometimes reaches $50-60$ degrees.

In temperate climatic zones, the maximum solar radiation occurs on the days of the summer solstices - in the Northern Hemisphere it is July month, and in the southern hemisphere - January. The reason for this lies not only in intense solar radiation, but also in the fact that the very heated surface of the planet gives off a huge amount of thermal energy.

Middle latitudes are characterized by higher annual amplitudes. Any place on the planet is characterized by its average and absolute air temperatures. The hottest place on earth is Libyan desert, where the absolute maximum is fixed - ($ +58 $ degrees), and the coldest place is the Russian station "East" in Antarctica - ($ -89.2 $ degrees). All average temperatures - average daily, average monthly, average annual - are arithmetic mean values ​​of several indicators of the thermometer. We already know that air temperature in the troposphere decreases with height, but in the surface layer its distribution can be different - it can increase, decrease or remain constant. The idea of ​​how air temperature is distributed with height gives vertical gradient temperature (VGT). Time of year, time of day, weather conditions affect the value of VGT. For example, the wind contributes to the mixing of air and at different heights its temperature levels off, which means that the WGT wind decreases. The VGT sharply decreases if the soil is wet, the fallow field has a VGT greater than that of a densely sown field, because these surfaces have different temperature regimes.

The sign of the VGT indicates how the temperature changes with height, if it is less than zero, then the temperature increases with height. And, conversely, if the sign is greater than zero, the temperature will decrease with distance from the surface and will remain unchanged at VGT = 0. Such a distribution of temperature with height is called inversions.

Inversions can be:

• Radiation (radiation cooling of the surface);
• Advective (formed when warm air moves onto a cold surface).

There are four types of annual temperature variation based on the average long-term amplitude and time of onset of extreme temperatures:

• Equatorial type - there are two maxima and two minima;
• Tropical type (maximum and minimum observed after the solstices);
• Moderate type (maximum and minimum are observed after the solstices);
• Polar type (minimum temperature during the polar night);

The height of a place above sea level also affects the annual course of air temperature. The annual amplitude decreases with height. Air temperature is measured by specialists at meteorological stations.

The sun's rays, passing through transparent bodies, heat them very weakly. For this reason, direct sunlight almost does not heat the air of the atmosphere, but heats the surface of the Earth, from which heat is transferred to the adjacent layers of air. When heated, the air becomes lighter and rises, where it mixes with colder air, in turn heating it.

As it rises, the air cools. At an altitude of 10 km, the temperature is constantly kept at around 40-45 ° C.

A decrease in air temperature with height is a general pattern. However, there is often an increase in temperature as you rise up. Such a phenomenon is called temperature inversion, i.e., a permutation of temperatures.

Inversions occur either during the rapid cooling of the earth's surface and adjacent air, or, conversely, when heavy cold air flows down mountain slopes into valleys. There, this air stagnates and displaces warmer air up the slopes.

During the day, the air temperature does not remain constant, but continuously changes. During the day, the surface of the Earth heats up and heats the adjacent layer of air. At night, the Earth radiates heat, cools, and the air cools. The lowest temperatures are observed not at night, but before sunrise, when the earth's surface has already given up all the heat. Similarly, the highest air temperatures are set not at noon, but around 3 p.m.

at the equator diurnal temperature variation monotonous, day and night they are almost the same. The diurnal amplitudes on the seas and along the sea coasts are very insignificant. But in deserts during the day the surface of the earth often heats up to 50-60 ° C, and at night it often cools down to 0 ° C. Thus, diurnal amplitudes here exceed 50–60 °C.

In temperate latitudes, the greatest amount of solar radiation reaches the Earth during the summer solstices, i.e. June 22 in the Northern Hemisphere and December 21 in the Southern. However, the hottest month is not June (December), but July (January), since on the day of the solstice a huge amount of radiation is spent on heating the earth's surface. In July (January) the radiation decreases, but this decrease is compensated by the strongly heated earth's surface.

Similarly, the coldest month is not June (December), but July (January).

At sea, due to the fact that the water cools and heats up more slowly, the temperature shift is even greater. Here, the hottest month is August, and the coldest month is February in the Northern Hemisphere and, accordingly, the hottest month is February and the coldest month is August in the Southern Hemisphere.

Annual amplitude temperature is largely dependent on the latitude of the place. So, at the equator, the amplitude during the year remains almost constant and amounts to 22-23 °C. The highest annual amplitudes are typical for territories located in the middle latitudes in the interior of the continents.

Any area is also characterized by absolute and average temperatures. Absolute temperatures established by long-term observations at weather stations. So, the hottest (+58 °C) place on Earth is in the Libyan Desert; the coldest (-89.2 °C) is in Antarctica at Vostok station. In the Northern Hemisphere, the lowest (-70.2 °C) temperature was recorded in the village of Oymyakon in Eastern Siberia.

Average temperatures is defined as the arithmetic mean of several thermometer readings. So, to determine the average daily temperature, measurements are taken at 1; 7; 13 and 19 hours, i.e. 4 times a day. From the figures obtained, the arithmetic mean value is found, which will be the average daily temperature of the area. Then the mean monthly and mean annual temperatures are found as the arithmetic mean of the mean daily and mean monthly temperatures.

On the map, you can mark points with the same temperature values ​​and draw lines connecting them. These lines are called isotherms. The most revealing isotherms are January and July, i.e. the coldest and warmest months of the year. Isotherms can be used to determine how heat is distributed on the Earth. At the same time, clearly expressed regularities can be traced.

1. The highest temperatures are not observed at the equator, but in tropical and subtropical deserts, where direct radiation prevails.

2. In both hemispheres, temperatures decrease from tropical latitudes to the poles.

3. Due to the predominance of the sea over land, the course of isotherms in the Southern Hemisphere is smoother, and the temperature amplitudes between the hottest and coldest months are smaller than in the Northern Hemisphere.

Number: 15.02.2016

Class: 6"B"

Lesson #42

Lesson topic:§39. Air temperature and diurnal temperature variation

The purpose of the lesson:

Tutorial: To form knowledge about the patterns of distribution of air temperature.

Developing I am : To develop skills, the ability to determine the temperature, calculate the daily rate, draw up graphs, solve problems of temperature changes, find the amplitude of temperatures.

Nurturing: To develop the desire to study the subject.

Lesson type: combined

Type of lesson: problem learning

Equipmentlesson: ICT, thermometers, weather calendars,

I. Organizational moment: Greetings. Identification of absentees.

II.Checking homework:

Test.

1. What reasons determine the heating of the Earth?

A polar night and a polar day

B angle of incidence of the sun's rays

In the change of day and night

G pressure, temperature, wind.

2. What is the difference in surface heating at the equator and temperate latitudes:

And the equatorial latitudes are heated more during the year

B equatorial latitudes are heated more in summer

In equatorial latitudes, they are heated equally throughout the year

3.How many lighting zones?

A 3 B 5 C 6 D 4

4. What are the features of the polar belt

A Twice a year Sun on the tropic

B During the year there is a polar day and a polar night

In Summer the Sun is at its zenith.

5. Does the weather often change in the tropical zone

A Yes B No C 4 times a year

III. Preparation for explaining a new topic: Write on the board the topic of the lesson, explain

IV.Explanation of the new topics:

Air temperature- the degree of air heating, determined using a thermometer.

Air temperature- one of the most important characteristics of weather and climate.

Thermometer is a device for measuring air temperature. The thermometer is a capillary tube soldered to a tank filled with a liquid (mercury, alcohol). The tube is attached to a bar on which the scale of the thermometer is applied. With warming, the liquid in the tube begins to rise, with cooling - to fall. Thermometers are outdoor and indoor.

Daily change in air temperature - amplitude.

Studies have shown that the temperature changes with time, i.e. during the day, month, year. The daily change in temperature depends on the rotation of the Earth around its axis.

At night, when there is no heat from the sun, the surface of the Earth cools. And during the day, on the contrary, it heats up.

As a result, the air temperature changes.

Lowest temperature of the day -before sunrise.

The highest temperature is 2-3 hours after noon

During the day, temperature readings at weather stations are taken 4 times: at 1 a.m., 7 a.m., 1 p.m., 7 p.m., then they are summed up and divided by 4 average daily temperature

For instance:

1h +5 0 C, 7h +7 0 C, 13h +15 0 C, 19h +11 0 C,

5 0 C+7 0 C+15 0 C+11 0 C=38 0 C:4=9.5 0 C

v.Assimilation of a new topic:

Test

1. Air temperature with altitude:

a) goes down

b) rises

c) does not change

2. Land, unlike water, heats up:

a) slower

b) faster

3. Air temperature is measured:

a) a barometer

b) a thermometer

c) hygrometer

a) at 7 o'clock

b) at 12 o'clock

c) at 2 pm

5. Temperature fluctuations during the day depend on:

a) clouds

b) the angle of incidence of the sun's rays

6. Amplitude is:

a) the sum of all temperatures during the day

b) the difference between the highest temperature and the lowest

7. The average temperature (+2 o; +4 o; +3 o; -1 o) is:

VI. Lesson summary:

1. determine the amplitude of temperatures, the average daily temperature,

VII.Homework:

1.§39. Air temperature and diurnal temperature variation

VII. Grading:

Evaluation teacher student

The daily variation of air temperature near the earth's surface

1. The air temperature changes in the daily course following the temperature of the earth's surface. Since the air is heated and cooled from the earth's surface, the amplitude of the daily temperature variation in the meteorological booth is less than on the soil surface, on average by about one third. Above the sea surface, the conditions are more complicated, as will be discussed further.

The rise in air temperature begins with the rise in soil temperature (15 minutes later) in the morning, after sunrise. At 13-14 hours, the temperature of the soil, as we know, begins to drop. At 14-15 hours, the air temperature also begins to fall. Thus, the minimum in the daily course of air temperature near the earth's surface falls on the time shortly after sunrise, and the maximum - at 14-15 hours.

The diurnal variation of air temperature is quite correctly manifested only in conditions of stable clear weather. It seems even more regular on average from a large number of observations: long-term curves of the daily temperature variation are smooth curves similar to sinusoids.

But on some days, the daily course of air temperature can be very wrong. This depends on changes in cloudiness that change the radiation conditions on the earth's surface, as well as on advection, i.e., on the influx of air masses with a different temperature. As a result of these reasons, the minimum temperature can shift even to daytime hours, and the maximum - to the night. The diurnal variation of temperature may disappear altogether, or the diurnal change curve may take on a complex shape. In other words, the regular diurnal variation is blocked or masked by non-periodic temperature changes. For example, in Helsinki in January, with a probability of 24%, the daily maximum temperature falls between midnight and one in the morning, and only in 13% does it occur between 12 and 14 hours.

Even in the tropics, where non-periodic temperature changes are weaker than in temperate latitudes, the maximum temperature occurs in the afternoon only 50% of all cases.

In climatology, the daily course of air temperature, averaged over a long period, is usually considered. In such an averaged diurnal course, non-periodic temperature changes, which occur more or less uniformly for all hours of the day, cancel each other out. As a result, the long-term curve of the diurnal variation has a simple character, close to sinusoidal.
For example, we present in Fig. 22 daily course of air temperature in Moscow in January and July, calculated from long-term data. The long-term average temperature was calculated for each hour of a January or July day, and then, based on the obtained average hourly values, long-term curves of the daily variation for January and July were constructed.

Rice. 22. Daily variation of air temperature in January (1) and July (2). Moscow. The average monthly temperature is 18.5 °С for July, -10 "С for January.

2. The daily amplitude of air temperature depends on many influences. First of all, it is determined by the daily temperature amplitude on the soil surface: the greater the amplitude on the soil surface, the greater it is in the air. But the daily amplitude of temperature on the soil surface depends mainly on cloudiness. Consequently, the daily amplitude of air temperature is closely related to cloudiness: in clear weather it is much greater than in cloudy weather. This is clearly seen from Fig. 23, which shows the daily course of air temperature in Pavlovsk (near Leningrad), averaged for all days of the summer season and separately for clear and cloudy days.

The daily amplitude of air temperature also varies by season, by latitude, and also depending on the nature of the soil and terrain. In winter, it is smaller than in summer, as is the temperature amplitude of the underlying surface.

With increasing latitude, the daily amplitude of air temperature decreases, as the midday height of the sun above the horizon decreases. Under latitudes of 20-30° on land, the average daily temperature amplitude for the year is about 12°C, under latitude 60° about 6°C, under latitude 70° only 3°C. At the highest latitudes, where the sun does not rise or set for many days in a row, there is no regular diurnal temperature variation at all.

The nature of the soil and soil cover also matters. The greater the daily amplitude of the temperature of the soil surface itself, the greater the daily amplitude of the air temperature above it. In steppes and deserts, the average daily amplitude

There it reaches 15-20 °С, sometimes 30 °С. Above a dense vegetation cover, it is smaller. The proximity of water basins also affects the diurnal amplitude: it is less in coastal areas.

Rice. 23. Daily variation of air temperature in Pavlovsk depending on cloud cover. 1 - clear days, 2 - cloudy days, 3 - all days.

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

3. It is clear that small diurnal temperature amplitudes on the sea surface also result in small daily air temperature amplitudes above the sea. However, these latter are still higher than the daily amplitudes on the sea surface itself. Daily amplitudes on the surface of the open ocean are measured only in tenths of a degree, but in the lower layer of air above the ocean they reach 1 - 1.5 ° C (see Fig. 21), and even more over inland seas. The air temperature amplitudes are increased because they are influenced by the advection of air masses. The direct absorption of solar radiation by the lower layers of air during the day and their emission at night also play a role.

Reasons for changes in air temperature.

The temperature of the air varies daily following the temperature of the earth's surface. Since the air is heated and cooled from the earth's surface, the amplitude of the daily temperature variation in the meteorological booth is less than on the soil surface, on average by about one third.

The rise in air temperature begins with the rise in soil temperature (15 minutes later) in the morning, after sunrise. At 13-14 hours, the temperature of the soil, as we know, begins to drop. At 14-15 hours it equalizes with the air temperature; from that time on, with a further drop in soil temperature, the air temperature also begins to fall.

The diurnal variation of air temperature is quite correctly manifested only in conditions of stable clear weather.

But on some days, the daily course of air temperature can be very wrong. It depends on changes in cloudiness as well as advection.

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

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

Reasons for changes in air temperature

Air in direct contact with the earth's surface exchanges heat with it due to molecular heat conduction. But inside the atmosphere there is another, more efficient heat transfer - by turbulent heat conduction. The mixing of air during turbulence contributes to the very rapid transfer of heat from one layer of the atmosphere to another. Turbulent thermal conductivity also increases the transfer of heat from the earth's surface to the air or vice versa. If, for example, air is cooled from the earth's surface, then by means of turbulence, warmer air from the overlying layers is continuously delivered to the place of the cooled air. This maintains a temperature difference between the air and the surface and therefore supports the transfer of heat from the air to the surface. temperature changes associated with advection - the influx of new air masses into a given place from other parts of the globe, are called advective. If air with a higher temperature flows into a given place, they speak of heat advection, if from a lower one, they speak of cold advection.

The general change in temperature at a fixed geographical point, which depends both on individual changes in the state of the air and on advection, is called a local (local) change.