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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