1. ITCZ (Doldrum)
The Inter Tropical Convergence Zone (ITCZ) is a belt of low pressure which circles the Earth
generally near the equator where the trade winds of the Northern and Southern Hemispheres
come together. This represents Wet part of the Hardly Cell.
Characterized by convective activity which generates often vigorous thunderstorms over
large areas. It is most active over continental land masses by day and relatively less active
over the oceans.
The position of the ITCZ varies with the seasons, and according to the sun's relative position
above the Earth's surface by about 1 to 2 months, and correlates generally to the thermal
equator.
Over land, the ITCZ tends to follow the sun's zenith point.
Where the trade winds are weak, the ITCZ is characterized by isolated Cumulus (Cu) and
Cumulonimbus (Cb) cells.
Clouds can be seen in this region because temperature is higher in this region and evaporation
is also higher. because of that cloud forming and rainfall is higher.
Equator has maximum average temperature throughout the year and the highest temperature
within whole year is related with ITCZ.
Because of tilt of 23.50
of the earth, Zenith point of the sun is not always with the equator.
2. In July - August, over the Atlantic & Pacific, ITCZ is between 50
and 150
north of the
Equator. Further north over the land masses of Africa and Asia. In eastern Asia, the ITCZ
may propagate up to 300
north of the Equator.
In January, over the Atlantic, the ITCZ generally sits no further south than the Equator, but
extends much further south over South America, Southern Africa, and Australia. the ITCZ
may propagate up to 200
south of the Equator.
ITCZ propagates poleward more prominently over land than over water (water has a higher
heat capacity than land) and over the Northern Hemisphere than Southern Hemisphere
In Indian Ocean summer ITCZ in the northern part of India will create a low pressure zone
which attract monsoon winds will attract towards Indian peninsula.
However, where the trade winds are stronger, the ITCZ can reach and sometimes exceed an
altitude of 55,000 feet, and the ITCZ can be as wide as 300 nautical miles in some places.
Aircraft flying through an active ITCZ (strong trade winds) will probably encounter some or
all the hazards such as icing, turbulence, lightning, and wind shear. However, it is in this zone
that the most severe effects may often be encountered.
