Air masses atmospheric fronts cyclones and anticyclones. atmospheric fronts

air masses- these are large air masses of the troposphere and lower stratosphere, which are formed over a certain territory of land or ocean and have relatively uniform properties - temperature, humidity, transparency. They move as one unit and in the same direction in the system of the general circulation of the atmosphere.

Air masses occupy an area of ​​thousands of square kilometers, their thickness (thickness) reaches up to 20-25 km. Moving over a surface with different properties, they heat up or cool down, moisten or become drier. Warm or cold air mass is called, which is warmer (colder) than its environment. There are four zonal types air masses depending on the areas of formation: equatorial, tropical, temperate, arctic (antarctic) air masses (Fig. 13). They differ primarily in temperature and humidity. All types of air masses, except for equatorial ones, are divided into maritime and continental, depending on the nature of the surface over which they formed.

Equatorial air mass is formed in equatorial latitudes, belt reduced pressure. It has rather high temperatures and humidity close to the maximum, both over land and over the sea. Continental tropical air mass is formed in the central part of the continents in tropical latitudes. It has high temperature, low humidity, high dust content. Marine tropical air mass is formed over the oceans in tropical latitudes, where rather high air temperatures prevail and high humidity is noted.

Continental moderate air mass is formed over the continents in temperate latitudes dominates the Northern Hemisphere. Its properties change with the seasons. Pretty in the summer heat and humidity, precipitation is typical. In winter, low and extremely low temperatures and low humidity. Marine temperate air mass forms over oceans with warm currents in temperate latitudes. It is cooler in summer, warmer in winter, and has significant humidity.

Continental Arctic (Antarctic) air mass is formed over the ice of the Arctic and Antarctica, has extremely low temperatures and low humidity, high transparency. Marine Arctic (Antarctic) air mass is formed over periodically freezing seas and oceans, its temperature is slightly higher, humidity is higher.

Air masses are in constant motion; when they meet, transition zones, or fronts, are formed. atmospheric front- the boundary zone between two air masses with different properties. The width of the atmospheric front reaches tens of kilometers. atmospheric fronts can be warm and cold, depending on what kind of air is moving into the territory and what is being displaced (Fig. 14). Most often, atmospheric fronts occur in temperate latitudes, where cold air from polar latitudes and warm from tropical latitudes.

The passage of the front is accompanied by changes in the weather. The warm front moves towards the cold air. It is associated with warming, nimbostratus clouds, bringing drizzling precipitation. The cold front moves towards the warm air. It brings heavy short-term heavy rainfall, often with squally winds and thunderstorms, and cooling.

Cyclones and anticyclones

In the atmosphere, when two air masses meet, large atmospheric vortices arise - cyclones and anticyclones. They are flat air vortices covering thousands of square kilometers at a height of only 15-20 km.

Cyclone- an atmospheric vortex of huge (from hundreds to several thousand kilometers) diameter with reduced air pressure in the center, with a system of winds from the periphery to the center counterclockwise in the Northern Hemisphere. In the center of the cyclone, ascending air currents are observed (Fig. 15). As a result of ascending air currents, powerful clouds form in the center of cyclones and precipitation falls.

In summer, during the passage of cyclones, the air temperature decreases, and in winter it rises, a thaw begins. The approach of a cyclone causes cloudy weather and a change in wind direction.

Tropical cyclones occur in tropical latitudes from 5 to 25° in both hemispheres. Unlike cyclones of temperate latitudes, they occupy a smaller area. Tropical cyclones occur over the warm sea surface in late summer - early autumn and are accompanied by powerful thunderstorms, heavy rainfall and storm-force winds, which have tremendous destructive power.

AT pacific ocean tropical cyclones are called typhoons, in the Atlantic - hurricanes, off the coast of Australia - willy-willy. Tropical cyclones carry a large amount of energy from tropical to temperate latitudes, which makes them an important component of global atmospheric circulation processes. For their unpredictability, tropical cyclones are given female names(for example, "Catherine", "Juliet", etc.).

Anticyclone- an atmospheric vortex of huge diameter (from hundreds to several thousand kilometers) with an area of ​​high pressure near the earth's surface, with a system of winds from the center to the periphery clockwise in the Northern Hemisphere. Downdrafts of air are observed in the anticyclone.

Both in winter and in summer, the anticyclone is characterized by a cloudless sky and calmness. During the passage of anticyclones, the weather is sunny, hot in summer and very cold in winter. Anticyclones form over the ice sheets of Antarctica, over Greenland, the Arctic, over the oceans in tropical latitudes.

The properties of air masses are determined by the areas of their formation. When they move from their places of formation to others, they gradually change their properties (temperature and humidity). Due to cyclones and anticyclones, heat and moisture are exchanged between latitudes. The change of cyclones and anticyclones in temperate latitudes leads to sharp changes in the weather.

Atmospheric fronts are formed in the border zone of 2 neighboring air masses. atmospheric front is a transition zone between two air masses with different physical properties. The atmospheric front between moving air masses intersects with the horizon plane at an angle of less than 1º, has a width in the horizontal plane of tens of kilometers and a vertical thickness of the order of hundreds of meters. The length of the atmospheric front reaches thousands of kilometers.

Special weather phenomena are associated with fronts. Ascending air movements in front zones lead to the formation of vast cloud systems, from which precipitation falls over large areas. Huge atmospheric waves arising in the air masses on both sides of the front lead to the formation of atmospheric disturbances of a vortex nature - cyclones and anticyclones, which determine the wind regime and other weather elements.

Major climate fronts:

Arctic (Antarctic) - on the border of AB and SW.

Polar - at the border of the SW and TV.

Intratropical - on the border of TV and EV.

As for any contact, bordering surface, the atmospheric front line is characterized by stormy, active processes of atmospheric mixing, the formation of atmospheric vortices, and the development of convective air rise.

Cyclones form along the lines of the Arctic and especially the polar fronts. This process is called cyclogenesis.

Cyclone. Cyclone (from the Greek kyklon - whirling) is a large-scale atmospheric disturbance of a vortex nature associated with an area of ​​low atmospheric pressure. The minimum atmospheric pressure falls on the center of the cyclone. Winds in a cyclone northern hemisphere directed counterclockwise, deviating in the lower layer towards the center; in the southern hemisphere - clockwise, with the same deviation in the lower layer.

Cyclone diagram (Z).

Anticyclone. An anticyclone is an area of ​​high atmospheric pressure with closed concentric isobars at sea level. The maximum pressure is in the center of the anticyclone and decreases towards the periphery. The air in the anticyclone moves in the northern hemisphere, going around the center clockwise (ie deviating to the right), in the southern hemisphere - counterclockwise. In the lower layer, the air current lines are in the form of spirals diverging from the center. The divergence of air currents in the lower layers entails the predominance of downward movements (settlement) of air in the anticyclone with a vertical component of the order of tens and hundreds of meters per day.

Diagram of an anticyclone (Az).

Cyclones (A) and anticyclones (B) (in the northern hemisphere)

Fronts constantly appear and disappear (blur) due to certain features of the atmospheric circulation. Together with them, air masses are formed and change their properties.

Fronts according to the nature of the movement of air masses are divided into warm and cold. The front is shifting towards a less active air mass. A more active air mass displaces a less active one from the territory. More active is the mass, where the baric gradient is greater.

warm front

warm is a front that moves towards cold air, because warm air is more active. It flows into the receding cold air, calmly rising up the frontal surface. Adiabatic cooling occurs, accompanied by moisture condensation and the formation of a powerful cloud system, which leads to precipitation. The length of the rainy zone reaches 600-700 km. In the place where warm air rises, i.e. a zone of low pressure is formed on the front line. The cold air is slowly receding. In general, a warm front brings warmth and moisture.

Cold A front occurs when cold air pushes warm air out of an area. The warm air mass is pushed upward by a wedge of cold air. The passage of the front leads to a change in the warm air mass to a cold one, and consequently, a decrease in temperature and sharp changes in other meteorological elements. The frontal surface is steeper than that of a warm front.

cold front

Depending on the degree of stability of warm air, cold fronts of the 1st and 2nd kind are distinguished.

Cold front of the 1st kind moves relatively slowly, the warm air in front of it rises calmly. The slope of the front is somewhat greater than that of the warm front, and the precipitation zone is smaller. The cloud system is dominated by nimbostratus (Ns), then altostratus (As), and then cirrostratus (Cs) clouds. Cumulonimbus clouds (Cb) are observed ahead of the front. Altocumulus clouds (Ac) are the harbinger of the front.

Cold front of the 2nd kind released when cold air quickly invades and actively pushes the warm air mass. The upward movement of warm air in front of the front in the lower part meets the downward movement along the frontal surface. An inversion occurs in front of the front at a height. Also, a powerful cloud system is formed in front of the front, mainly from cumulonimbus clouds (Cb), squally winds, showers with thunderstorms, often with hail are characteristic. But the front passes quickly and the weather improves.

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Attention! The slide preview is for informational purposes only and may not represent the full extent of the presentation. If you are interested this work please download the full version.

Using the MS office "Power Point" software application, I have the ability to quickly access the necessary information, the ability to view in the mode that is necessary at the moment - to speed it up or, conversely, slow it down while explaining the topic.

During a slide lecture, the student perceives information both visually and auditorily, which creates favorable conditions for understanding and assimilation of the material being studied.

For the lesson, a new pedagogical technology is used - a slide lecture. The advantages of using a slide lecture is that students focus on the main points educational material. Students do not just listen to a lecture, but see visual material about weather phenomena. The lesson successfully combines oral lecture material with the image of photographic materials, maps, videos. Control of assimilation of the material is carried out by filling in the table.

Students receive more than enough information on a given topic and learn to apply it in practice.

Lesson Objectives:

• Educational: to give an idea of ​​atmospheric fronts, cyclones, anticyclones and their influence on the weather.
• Educational:
  • to highlight the main thing, to ensure that students comprehend and assimilate new material;
  • determine and explain the state of the weather in our area in given time;
  • develop the ability to determine weather conditions for the near future using synoptic maps.
• Educational: contribute to the education of observation for signs weather events and interest in weather forecasting.

Lesson objectives:

• promote the development of cognitive interest in weather forecasting;
• improve the ability to analyze and work with synoptic maps;
• cultivate observation.

Equipment: geography atlases, DER "Warm and cold atmospheric fronts", synoptic map of Russia, satellite images, presentation "Regularities of air mass circulation. Atmospheric fronts, cyclones and anticyclones", multimedia equipment with a projector, a table for self-control "Comparative characteristics of a cyclone and anticyclone"

Methods and forms of educational activity: overview lecture with elements of conversation and practical activities of students.

DURING THE CLASSES

I. Organizational moment

The teacher checks how comfortable the students feel, the readiness of the workplace, creates a situation of success

1. Before studying new topic the teacher poses a problematic question, to which students must answer and determine the topic of learning new material.
- What will we study today in the lesson based on the photographs we have seen? (SLIDES 1, 2)
“Regularities of the circulation of air masses. Atmospheric fronts, cyclones and anticyclones.(SLIDE 3)

2. In the 7th grade, we studied climate-forming factors. Let's remember them and determine which of them strongly affects the state of the weather? We will study this factor today. (SLIDE 4. Answer: “Movement of air masses”)

II. Motivational moment:

- Today at the lesson we

• we will get acquainted with synoptic maps, learn how to “read” them, determine the movement of air masses.
• Find out how the weather forecast for the near future is made.
• determine the weather for tomorrow and the day after tomorrow (for your area).

III. Exploring a new topic:

- As you may have guessed, we will talk about clear and cloudy weather, about its prediction.
- Determine what day it will be if we observe fog in the morning? (SLIDE 5)
Do you remember seeing fog in the morning? (Students answer)
The teacher starts the explanation on this example.

This natural phenomenon is due to the fact that the cold morning air collides with the incoming warm air. When two air masses collide with different temperatures mist forms. The greater the temperature difference, the thicker the fog will be. (SLIDE 5) At the same time, the day will be clear, and the air temperature will be warmer.
(SLIDE 6) Definition of the concept of "air mass".
(SLIDE 7) Types of air masses found near the earth's surface.
(SLIDE 8) The movement of air masses is very well visible from space. What does each of these space images remind you of? (Answer: The movement of the fan blades)
(SLIDE 9) Using the example of a slide, we can determine the direction of movement of such a vortex, which means that we can determine what kind of weather this vortex flow will bring. This is how weather forecasts are made for the near future using satellite images of air masses.
There are two types of air masses: cyclones and anticyclones.
(SLIDE 10) Cyclones are a low-pressure eddy at the center. Let us consider the mechanism of cyclone formation and its characteristics. The main direction of movement of cyclones from the west (Atlantic Ocean) to the east.
(SLIDE 11) An anticyclone is a vortex with high pressure in the center. Let us consider the mechanism of anticyclone formation and its characteristics. They come mainly from the central and southern regions continental climate. The land warms up faster, so the heat comes with a drought in summer. In winter, the continent cools faster, the air is clear and frosty. The largest anticyclone forming over Eurasia is the Siberian anticyclone.
(SLIDE 12) What atmospheric vortices will bring such weather to our area? (Based on photographs of the weather in Zimovniki, students determine where the cyclone dominates and where the anticyclone)
(SLIDE 13) We consolidate the ability to determine the name of the prevailing air currents.
(SLIDE 14) All air vortices move one after another, changing the weather. After viewing the DRCs about the warm and cold fronts, we determine:
- When does it rain?
– When is it drizzling?
Warm: http://www.youtube.com/watch?v=xdd1b3XBPCg
Cold: http://www.youtube.com/watch?v=UAvlyBF7tb8
(in the folder there is a video of warm and cold fronts, if it does not open in the presentation)
(SLIDE 16) Video of the warm front.
(SLIDE 17) Cold front video.
Now let's get acquainted with the synoptic map. Seeing it, we can immediately make a weather forecast for our area, without waiting for it to be announced.
(SLIDE 18) How are cyclones depicted? Their directions? How are anticyclones depicted?
What will the weather be like in Sverdlovsk (now Yekaterinburg) if the cyclone is leaving and the anticyclone is approaching? (Answer: Cloudy and rainy weather will be replaced by clear and sunny weather in a day. Warming starts on March 16)
(SLIDE 19) What will the weather be like in Rostov-on-Don in summer? (Answer: Cold weather, cloudy and rainy weather).

IV. Practical part lesson: Fill in the table to consolidate the studied material. (SLIDE 20)

Comparative characteristics of a cyclone and an anticyclone: ​​(SLIDE 21) We check the answers.

Reflection:

1. Determine what kind of weather (cyclone or anticyclone) is referred to in the poem by A.S. Pushkin?

• Today in class I had...
• The knowledge gained in the lesson will be useful to me ....
• Today I…..
• It was easy for me...
• It was difficult for me...
• What I have learned (a), I will tell ...

3. (SLIDE 23)

- Let's look out the window. What's the weather now?
- On what grounds did you come to this conclusion?
- What will happen to the weather if a cyclone is approaching?

Summing up the lesson. Homework: paragraph 11 on pages 73-80.

– Today I wanted to show the variability of the weather and explain the reasons for changes in the state of air masses. It is in the classroom that learning takes place. practical application acquired knowledge in the form of forecasting the weather for the near future using a synoptic map. When going to school, students will consider the weather of today, scientifically explaining it. But they will get more satisfaction from the correct prediction of the weather for tomorrow. (For example, with the rapid approach of a cyclone in September, we predict strong wind and cold rain). Poems show the state of the weather, and the teacher tries to consolidate the knowledge gained by students in practice and develops the ability to explain the processes occurring in the atmosphere. Interest in this issue is the driving force in the acquisition of knowledge. I want to believe that my lesson will be tested by many teachers. And the presentation for the lesson will be reference summary for the lesson.

Rain... Snow... Penetrating wind... Burning sun... These manifestations of the weather are familiar to each of us from deep childhood. But even having diligently studied geography at school, we are still sometimes surprised by sudden changes in temperature and unusual natural disasters. Atmospheric fronts are invariably associated with climatic shocks. They shape everyday weather and define the boundaries of the seasons.

atmospheric front

The word "front" (from the Latin "frontis" - forehead, front side) implies a fine line between something. It can pass, for example, between different areas of combat operations: areas of concentration of enemy forces and a friendly army. If we use the phrase "atmospheric front", then we mean a boundary in the air, a certain boundary in the atmosphere. What exactly does he share, and how does it affect us?

Mother nature has shaped favorable climate in which a person can exist, multiply and develop. We live in the troposphere, the lower part of the atmosphere, which not only provides us with oxygen, but is in constant motion. Some voluminous in it interact from time to time. In the middle of each of these formations there are small pockets of microclimate, which differ in properties, but are generally homogeneous, maintaining a stable temperature and humidity. Masses move over the surface of the Earth, meet and even collide. But they never mix. The boundary between them is called the atmospheric front.

Main types

The width of the strip between air masses of the same properties reaches tens, sometimes hundreds of kilometers. where there are always jumps in air pressure, changes in cloudiness and temperature. That is, it is in these areas that one can observe how the hot sun is replaced by cold rain and vice versa. If very close, in fact, homogeneous masses come into contact, an atmospheric front does not arise. As a result, the weather does not change.

There are several fronts. They were formed on the basis of the main indicators of which remain constant.

1. Arctic. Separates cold arctic air from temperate air.
2. Polar. Located between temperate and tropical air masses.
3. Tropical. This is the border between the tropical and equatorial zones.

In the case of complete immobility, the front would take a horizontal position. In this case, the layer of cold air would always be at the bottom, and warm - at the top. But as a result of constant cyclicity, it is located at an angle to the surface of the earth.

cold front

Whether the weather in our region will change and what it will be - all this will be demonstrated by a map of atmospheric fronts. It clearly shows that the warm front is always inclined in the direction in which it moves, the cold one - in the opposite direction. When the latter moves into a zone of high temperature, and penetrates into it in a kind of wedge, pushing it up, cooling sets in in this territory. Warm masses gradually cool down, moisture is released from them - this is how clouds and clouds are formed.

Rain is the first sign of a cold front approaching. cumulus that appear on the horizon. At the same time, the wind blows in gusts, sharply changing direction. The wall of pouring rain collapses suddenly. The sky is gloomy, it is cut by lightning, thunder rumbles, sometimes there is hail. The storm lasts no more than two hours, after which the precipitation stops. The air temperature drops, sometimes by 5-10 degrees at once, since the atmosphere completely occupies cold front, displacing the air warmed by the sun.

warm front

It is formed when a zone of high positive temperature "flows" onto a cold mass. She seems to be sliding on it, gradually rising. The weather changes smoothly, without unexpected sudden jumps and drops. Spindrift clouds- the first sign that an atmospheric front is approaching, in the center of which there is a rather high air temperature. There is no wind yet. If it is, then its breaths are always pleasant and light.

Gradually, the clouds melt, and a continuous white veil of small layered formations that move across the clear blue sky. After some time, they bunch up: a dense layer sinks lower, the wind rises, it drizzles, or light snow falls. Precipitation intensifies, lasts for several hours, sometimes days, after which warming sets in. Good weather does not last long. The atmospheric front, in which the temperature is low, catches up with the heat zone, as it moves faster and more rapidly.

Cyclone

The air on the earth's surface is unevenly distributed. As a result, zones with high and low pressure are formed. In the first region, air is in excess, in the second - in short supply. From the zone of high pressure, it flows out, as if pouring over the edge of the glass, and fills the formed "holes" in the area where we call this natural phenomenon wind.

The area of ​​low pressure is the cyclone. It has the shape of a whirlwind. Watch how water flows out of the sink - it forms a funnel. The same principle shows us the weather. Cyclone - the same funnel in the sink, only turned upside down. In its center is a low pressure pole, which draws in air from all sides and rushes up, and it twists clockwise in and against - in the north. It is cloudy inside the cyclone, because together with the wind it "sucks" the clouds into itself. They slide down a hill into it from those areas where the pressure is high.

Anticyclone

It works exactly the opposite. There is high pressure in the center, there is a lot of air there, so it spreads in all directions, as if cream squeezed out of a confectionery bag. The currents swirl clockwise in the northern hemisphere, counter-clockwise in the southern. To give another example, if you draw a carbonated drink into a straw and then release it, it will invariably drain into a glass. A similar phenomenon occurs in an anticyclone. Only with the help of air and on a global scale.

The weather in the anticyclone is usually clear, as high pressure forces clouds out of this area. At the same time, it is always very hot in summer: there are no barriers in the form of clouds that prevent the sun from warming up the air. In winter, the opposite is true. The sun is low enough, but it cannot warm the air: there are no clouds, and therefore nothing retains heat. As a result, in winter, when the anticyclone comes, the weather is clear but frosty. By the way, by studying atmospheric fronts, cyclones and anticyclones, their movements, modifications and transformation, weather forecasters make a weather forecast for a particular region.

What does the coming day have in store for us?

The most difficult thing, forecasters say, is to predict the weather for the next three days. That is, after collecting all the necessary information, you need to quickly process it, taking into account all the vagaries of atmospheric fronts, changes in cyclones and anticyclones. And only by comparing the data, you can draw a conclusion.

Weather forecasts are as follows:

1. Short-term - a maximum of three days.
2. Medium-term - up to ten days.
3. Long term forecast weather - for a month or a season.

The first two types are the solution by weather forecasters of the equations of thermodynamics and dynamics, which describe the state of the atmosphere. To do this, experts analyze the possibility of a change in precipitation, expected jumps in pressure and air humidity. A long-range weather forecast is never completely accurate. Even with the latest equipment, weather forecasters cannot foresee all the surprises nature has in store. But in any case, it is necessary to make it, since such a forecast refers to the expected monthly or seasonal weather anomalies.

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Slides captions:

The movement of air masses. atmospheric fronts. Cyclones and anticyclones.

Warm weather front

cold front

Cold front Warm front 1. Formed when cold air invades an area occupied by warm air. 2. Penetrates with a wedge, pushing the TV up. 3. The weather changes quickly. Downpour, thunderstorm, squally wind. 4. After the passage of the front cooling. Formed when warm air enters an area occupied by cold air. 2. It rises smoothly above the XV, pushing it back. 3. The weather changes gradually, it rains heavily. 4. After the passage of the front - slow warming. The atmospheric front is a strip that separates air masses of different properties.

Cyclones Anticyclones atmospheric vortex with low pressure in the center Atmospheric vortex with high pressure in the center The movement of air from the outskirts to the center counterclockwise The movement of air from the center to the outskirts clockwise In the center - ascending air movement In the center - descending air movement The weather is changeable, windy, cloudy, with precipitation. The weather is stable, windless, cloudless, without precipitation. Warm in summer, cold in winter.

Synoptic map 1. What season is shown on the map? 2. Where is the lowest pressure in the country? 3. How many cyclones (anticyclones) are recorded on the map? 4. Where is the most low temperature and what is it equal to? 5. What condition of the sky prevails over the country? 6. Where is a cloudless sky over the territory of the country? 7. Why are synoptic charts made?

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