Page 87 - The World About Us

Erg Chebbi
1.1.1
1.1.1
2.2.3
2.3.4

Where are the planet’s main climatic zones?

The Earth has several very meet), the high pressure results in rain is a common feature.
different clima c regions. These are clear skies and li le rainfall. Regional climates are also affected
determined by la tude, al tude and Some areas, because of the lt of by distance from the sea. Inland areas
distance from the sea, as well as by the Earth at 23½ , may experience have a far greater range of
atmospheric circula on.
both rising and descending air at temperatures between winter and
Tropical and sub-tropical regions different mes of the year. This is true summer. Mountain ranges can
can have one of three general of the wet and dry regions of tropical increase rainfall or create rain
climates. In Equatorial regions under Africa (see pages 16-17) or the shadows, depending on the direc on
the Inter-Tropical Convergence Zone Mediterranean, which receives high of the prevailing winds (see page 7).
(ITCZ), where air from the two Hadley pressure and dry weather in the The high, dry Tibetan Plateau
Cells meet, the rising air and low summer and low pressure and rainfall north of the Himalayas creates a zone
pressure results in cloud forma on during the winter months. of rising air and low pressure during
and heavy rainfall (see pages 10-11).
Descending air at the Poles creates the summer. This pulls the ITCZ
In areas under descending air, such dry weather but, at the Polar Front northwards, crea ng the condi ons
as at the Sub-Tropical High Pressure where the Polar and Ferrel Cells meet, for India's torren al monsoon rain
(where the Ferrel and Hadley Cells the weather is generally unstable and from June to September.

Fig.226 Antarc c peninsula. Fig.227 Temperate autumn, Lake District, UK. Fig.228 Rainforest, Costa Rica.
POLAR REGIONS. Towards the Poles, TEMPERATE REGIONS. Found mostly EQUATORIAL REGIONS.
beyond the Arc c and Antarc c between la tudes 40 and 60 north and Within 5 north and south of
circles, the Polar regions are south, these climate zones tend to have four the Equator, the climate is
dominated by an intensely cold dis nct seasons and significant temperature characterised by high annual
temperature, carried on strong ranges between the highs of summer and rainfall and high, stable
easterly winds. the lows of winter. temperatures. Humidity keeps
night me temperatures almost
as warm as the day.
66 / N
60 N
WET AND DRY TROPICS.
North and south of the
Equatorial regions, these are
transi onal areas affected by
30 N both the ITCZ and the STHP. A
Tropic of Cancer
23 / N rainy season starts when the
ITCZ is overhead and the dry
season arrives when the area
0 Equator is under the STHP.

SUB-TROPICS. These areas
Tropic of Capricorn
23 / S between 20-30 north and
south are dominated by high
30 S
pressure associated with the
STHP. Clear skies give high
temperatures and li le rain,
but can result in temperatures
60 S Fig.229 Earth’s main clima c zones. falling significantly at night.
66 / S

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The global circulation of the atmosphere controls weather and climate.