PRIMARY WIND/GENERAL
CIRCULATION OF ATMOSPHERE/TRICELLULAR MERIDIONAL CIRCULATION:
The winds that flow throughout the year from one latitude to
another latitude because of latitudinal differences in the air pressure are called
planetary winds. They are also called prevailing winds. Planetary winds blow
from a single direction over a specific area over the earth.
EQUATORIAL LOW
PRESSURE BELT:
During the equinox condition, because of direct sun rays, the equatorial receives high temperature so the air particles around it gets heated and rises up. It create low pressure system in the surface of the equator is called equatorial low pressure belt.
The
vertical rising of air throughout the
year result into the conventional rainfall. Throughout the latitudes 5’N
to 5’S. This rainfall is often called as four ‘o clock rainfall. This
region also has converge of northern and southern trade winds this is called
intertropical convergence zone.
This
belt marked with equatorial rainforest like amazon, Indonesian rainforest , congo
zaire rainforest etc.. In upper troposphere the ascended air particles get converged
towards polar region.
This low pressure belt is also known as doldrums
because it is a zone of total calmness without any breeze.
POLAR HIGH PRESSURE BELT:
Because of slanting sunrise the temperature around both the poles will be low which results into sinking or descending of air around the polar region which creates polar high pressure belt between 80'N and S to North Pole, South Pole. The sinking air hits the earth surface and moves towards the poles as polar easterlies.
