§ 33. The air mass. Cyclones and anticyclone (textbook)

§ 33. Air mass. Cyclones and anticyclone

 

Remember what the thermal zones.

As thermal zones are located on the ground?

 

Concept of air masses. Scientists find that air troposphere is changing with height. It takes different properties depending on addition, over which the surface is. For example, over the equator and hot air wet. Above the Arctic ice and snow it is cold, dry and transparent. Over thermal waters of the Atlantic Ocean it is warm and wet and hot over deserts in the summer - dry, hot, dusty. As a result, the entire troposphere though some are moving parts - Air mass with different properties: temperature, humidity, dust. By sizes are huge - the size of a part of the ocean or continent. They moved in different directions collide, replacing one another.

Thus, in various parts of the world air mass can be warm or cold, wet or dry, dusty or transparent. Such properties of the air becomes, if a long time is over a certain surface.

Consider, as a born air masses as they move, change and cease to exist.

Depending on the district formation distinguish equatorial, tropical, moderate (in both hemispheres) and Arctic (Antarctic) air masses. By their names easily identified by their properties. Over moderates dominate the territory of Ukraine, but come and arctic and tropical air masses.

If the air mass formed over the ocean, it will be different from that formed over the continent. Summer ocean water Colder than dry and warmer in winter. Therefore, maritime air mass in summer - cold in winter - heat in comparison with continental air. Air weight than equatorial, may be wet (Sea)And dry (Continental).

Thus, the cause of various air masses is uneven heating of the earth's surface by the sun and its various properties in different heat zones.

Moving and changing air masses. Air masses formed inevitably begin to move. You already know that the cause of their movement is uneven heating of the surface and, consequently, the difference in atmospheric pressure. Moving air masses is the main cause rapid changes in weather. This is it hot sunny weather in summer can suddenly change to cold and rainy in winter bring a thaw after heavy frost. When it's cool, talk about coming of the cold air mass. A warming mean the arrival of warm air mass.

Air masses retain their properties long time. However, moving further and further all over the earth's surface, they change: lose or replenish moisture or heat. Thus, moderate maritime moist air, moving over land gradually heated and dried, becoming continental.

Cyclones and anticyclone. The word "cyclone" we often hear in messages about the weather. In Greek it means "one who circled. The very name indicates circular movement of air that occurs nand boundary of two air masses. Cyclone - A huge atmospheric vortex diameter of 3 000 km of low pressure in the center. So air moves from the edge of the vortex to the center. But under deflective force Earth's rotation in the cyclone wind starts to deviate, envelope area of low pressure clockwise in the northern and clockwise in Southern Hemisphere. It's like a giant gyroscope air, which for a week or two moves at a speed of 40 km / hr. Passage of cyclone accompanied by a windy, cloudy weather with precipitation. In summer it is cold in winter - warming. The weather in Ukraine affect cyclones that arise over the northern Atlantic. Every year it happens to us 40.

Specific is tropichni cyclones. They arise in tropical latitudes over warm ocean areas (with temperature Water 28 0C). In the tropical cyclone accumulate clouds, raging rains, storms, storm winds. But interestingly, in the center of the cyclone quietly. They formed area 30 kilometers in diameter clarification, called the eye of the storm. Tropical cyclones in Asia called typhoons, Australia - Willie-Willie, America - hurricanes (Hurricane). They bring great destruction, heavy rains, the water nahanyayut coast, causing flooding. Every year on Earth there are about 120 tropical cyclones. In the twentieth century. they were given names. HurricaneKatrina, Which appeared near the southeastern U.S. coast in 2005, was one of the most violent in recently. He has inflicted terrible damage. Despite the cautionary measures killing many people.

Anticyclone - Other atmospheric vortices formed in one air mass. In its center - the pressure is high. Because the wind is directed from the center its edges. Because of Earth's rotation winds deviate clockwise clockwise in the Northern Hemisphere and counterclockwise in the South.  Summer anticyclone bringing cloudy warm and hot weather even in winter - clear, dry and frosty.

Value moving air. The atmosphere is not something static, it is moving. Moving air in it is financed by a combination of horizontal and vertical movement. Not accidentally called air atmosphere ocean, where there is Air flow - winds. Diligence winds, their inexhaustible energy have long been known. They tolerate heat and moisture from one in other latitudes, from the oceans deep into continents. With the general movement of air heat and humidity on Earth redistributed. If there was no air moving, then the equator would much hotter (About 13 0C) and near poles are much colder. Wind - a powerful force that carries out the destruction, and brought up in other areas of particle species.

People and yourself from ancient times learned to use airflow. Wind worked in the windmill, where ground it grain flour, the sailing ships, which overcame the sea and rivers. Now using the wind motors receive electricity.

 

FAQ task

1. What causes the formation of various air masses?

2. What properties distinguish one air mass from another?

3. What are the air masses dominate over the territory Ukraine?

4. How will the weather after the arrival of anticyclone winter?

5. How does the movement of air masses on the distribution heat and moisture on Earth?

6. Can a cyclone formed over Antarctica?