Cyclones, anticyclones, typhoons, hurricanes, tornadoes, tornadoes - these phenomena are caused by vortex movements in the atmosphere, accompanied by precipitation (greater or lesser). Consider the characteristics and conditions for the occurrence of this element.
Movement of air masses in the atmosphere
In the atmosphere of our planet there is a constant circulation of air masses with the transfer of energy and material components. Movement in progress:
- from north to south and in the opposite direction (meridional);
- from west to east and in the opposite direction (latitudinal).
In the troposphere, in addition to meridional and latitudinal transfers of air masses, there are eddy movements of the atmosphere, accompanied by precipitation - cyclones and anticyclones.
These phenomena cause changes in climatic conditions in all regions of the planet.
In the lower layers of the troposphere, in the tropical zone, the air masses heat up quite strongly. At the same time, the air masses are filled with moisture (especially over the oceans). Warm air risesup to a height of 1000-1200 meters, where it begins to cool with the subsequent formation of clouds. In place of the raised warm masses, cold northern masses (in the northern hemisphere) come. Warm air masses are captured by the Coriolis force caused by the Earth's rotation. They begin to move not only upwards, but also horizontally, while deviating from a rectilinear direction - in the northern hemisphere to the northeast. Cold masses go to the southwest (in the southern hemisphere, air masses move in exactly the opposite direction). This is how the trade winds are formed.
The water surface of the ocean, warmed up by the end of summer and the beginning of autumn, provides an opportunity for the formation of other air masses filled with moisture - monsoons. Their direction is strictly opposite to the trade winds.
The thermal equilibrium of the planet is maintained due to global inter-latitudinal transfer: heat from tropical latitudes to high latitudes, cold from subpolar (high) latitudes to the tropics.
The cyclonic activity of the atmosphere is based on the connection of tropical circulation with the eddy activity of air masses in temperate latitudes.
Cyclogenesis
This term refers to the formation, development or collapse of the vortex motion of the atmosphere, accompanied by precipitation. That is, just any cyclone - a vortex with low pressure inside. "In the bowels" of the cyclones of the northern hemisphere winds blow counterclockwise. The lower region of the cyclone is characterized by the deviation of the wind towards its center.
Modern meteorology divides cyclonic eddies into two types: according to their locationorigin and subsequent activity - tropical and extratropical (temperate cyclones).
The first are formed in the tropics, with development they reach a size of up to a thousand kilometers (very rarely more). The second is the vortex motion of the atmosphere in the zone of temperate and subpolar latitudes. Extratropical cyclones reach huge (up to several thousand kilometers) sizes.
The speed of the eddy movement of air in tropical cyclones is huge, it can reach storm values. These eddies can become extratropical as they move.
Conditions necessary for the formation of a tropical eddy motion
In order for a tropical vortex to form, it is necessary that the surrounding air be saturated with moisture (this gives an instability factor). The water in the ocean warms up to a depth of fifty meters, to a temperature of more than twenty-six degrees Celsius. When vapors condense in the lower layers of the troposphere, the air must cool very quickly (this is the main energy source of the cyclone).
Typhoons and hurricanes - tropical cyclones
In the Far East and in the countries of Southeast Asia, tropical eddy movements of the atmosphere accompanied by precipitation are called typhoons. In the countries of North and South America - hurricanes (among the Mayan Indians, the god of the wind is Hurakan). If the speed of a storm during a storm exceeds one hundred and seventeen kilometers per hour, then this is already a hurricane.
Tropical cyclones bring heavy rains. At sea, during a typhoon and a hurricane, huge waves arise. But they are weakened by falling underwind action on land. Downpours caused by tropical cyclones fall inland at distances of up to forty kilometers. This is very important for mitigating the dry climate of the continents.
The cyclones themselves carry energy reserves from one place on the planet to another, from the tropics to temperate zones. This is important for global cyclonic processes in the atmosphere, because it leads to a convergence of temperatures on the planet, leveling the climate and making it milder.
Extratropical cyclones and anticyclones
Huge in size (several thousand kilometers) eddy movements of the atmosphere, accompanied by precipitation and occurring in temperate and subpolar zones, are called extratropical cyclones and anticyclones. Wind eddies in northern cyclones rotate in the same direction as northern typhoons.
With the advent of such a hurricane, inclement weather sets in, but the anticyclone brings a clear and sunny day.
Occurrence of cyclones of temperate latitudes
To represent the mechanism of occurrence of these formations, it is necessary to operate with the concept of an atmospheric front. In the first approximation, this is just a border separating two different air masses.
In fact, this is a zone of several tens of kilometers, tilted at an angle of one degree. In the case of a warm front, its slope lies in the direction of motion (it, as it were, covers the cold mass from above). When cold - on the contrary, in the opposite side of the movement. The equation of motion of the atmosphere is expressed through the formula of Max Margules(Australian meteorologist).
The interaction of warm and cold fronts leads to the formation of a cyclonic vortex. With such a connection, part of the warm front is introduced into the cold mass in the form of an elongated "tongue". At the same time, warm air rises as lighter air.
During this interaction, two processes occur, leading to a cyclonic vortex. Molecules of steam (water), rising, begin to rotate: they are affected by the magnetic field of the Earth. They involve in this rotational movement all the surrounding air. As a result, a huge whirlpool is formed from it and water molecules.
At the top, the air masses are cooling. In this case, water vapor condenses, which turns into clouds (these are subsequent rain, hail, snow). Such weather with bad weather can linger for several days, or even weeks. This will depend on the "longevity" of the cyclone: the greater the supply of warm air, the longer the cyclone exists.
Occurrence of anticyclones
The emergence of this vortex is due to the lowering of the atmospheric masses when they are heated with the surrounding masses, without heat exchange. During this process, the humidity inside falls, and this entails the evaporation of already existing clouds. Under the influence of the Earth's magnetic field, water molecules begin to rotate - in the northern anticyclones - clockwise. Steady weather in this process can last up to three weeks.
