Friss tételek

The Global Air Circulation




On the sphere-shaped gömb alakú Earth warming up differs at the different places. It is the strongest along the Equator, and the weakest at the poles, and due to this the air pressure is low at the Equator and high at the poles. Low pressure zones form in the district of the latitude 60 and high pressure zones around the latitude 30. Due to the cyclones and anticyclones forming in the jet streams, the moving of the air is ascending (low-pressured zones) and descending (high-p.z.).


Jet streams: they are specially strong winds, can be observed between latitudes 30 and 40 in large heighth (8-12 km). They form the cyclones which indicate the low pressured zones around the polar circles. The anticyclones form the high pressured zones around the tropicstérítők.

Wind systems: The spheres of air (around the Earth) are permanently moving. The system of their movement is called the great air movement of the Earth. It is the change of air between the areas with different air pressure.

The direction of air convections is modified by: - the rotation of the Earth
- frictional force (súrlódási erő)

Three wind systems evolve(keletkezik) close to the surface: - eastern trade winds
                     - westerly winds
                     - eastern polar winds

1.) Trade winds:
Definition: between the Equator and latitude 30 in the temperate zone the air close to the surface flows towards the Equator. This wind on the northern hemisphere is northeastern-directed, on the southern southeastern-directed. They almost always blow, their direction does not change.

2.) Westerly winds:
Definition: they are located between latitude 30 and 60, their engine are jet streams which also influence their direction. The cyclones and anticyclones carried by the jet streams are drifted (sodor) to the east by the westerly winds.

The operation of the global air circulation:

At the Equator: - due to the warming, and the meeting of the trade winds the air ascends and 
                            in a 2-4 km height flows apart  à there is the equatorial doldrums
                            (egyenlítő körüli szélcsendzóna) here, showers and cloud formation are
                            constant

Around latitude 30 degrees: - the air descends à high-pressured zone
                                - weather is dry and serene (derült)




Between latitudes 30d and 60d: - the winds coming from the west saturate with water vapour
                                                     above the ocean and gives precipitation to the western
                                                     coasts of the continents (à that is why the amount of
                                                     precipitation decreases from the west to the east)

At the poles: - the heavy, cool air accumulates à air pressure is high
- from the high-pressured zones the air flows away in a northern and southern
  direction, but due to the Coriolis force at the poles it happens in a southeastern
  and norteastern direction.

Both the tropical and polar volumes of air get into the temperate zone sometimes. 

The largest irradiation (besugárzás) and the warming are not always the largest at the Equator because of the  tilted axis of the Earth. The isotherm line connecting the seasonally warmest points of the Earth is called the Thermal Equator. It is not a straight line because of the different warming of the continents and seas. It moves to the north in the summer of the northern hemisphere and to the south in the summer of the southern hemisphere.
                                                      
-          the wind systems complies with (igazodnak hozzá) the hőm. egyenlítő
-          the high-pressured air evolving at the tropics flows towards the hőm. egyenlítő à that is why the trade winds pass the (sidereal=csillagászati) Equator and due to the rotation of the Earth change their direction. à northeastern trade wind becomes northwestern
                                                               wind on the southern hemisphere (in the winter
                                                               of the northern hemisphere)
                                                          à the southeastern trade wind becomes southwestern
                                                               wind (in the summer of the northern hemisphere)
   





                                

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