Near the equator, trade winds of the Northern
and Southern hemispheres converge.
In this region, strong sun and warm water
heats the air, raising humidity and making
the air more buoyant.
This region where this occurs is called the
Intertropical Convergence Zone and the Doldrums
by sailors.
Referred to as the doldrums because of the
relatively windless ocean surface, the ITCZ,
or “itch”, circles the Earth, and appears
as a band of clouds consisting of showers,
with occasional thunderstorms.
This band of clouds may extend for hundreds
of miles and can be broken into smaller line
segments.
These clouds and storms develop from the convergence
of the trade winds aiding the buoyant air
to rise.
The rising air expands and cools, releasing
the accumulated moisture in an almost perpetual
series of thunderstorms.
These storms can be short lived but can produce
heavy rainfall.
It’s estimated that 40% of all tropical
rainfall rates exceed one inch per hour.
The ITCZ follows the sun, it moves north in
the Northern Hemisphere summer and south in
the Northern Hemisphere winter, which results
in the wet and dry seasons of the tropics
rather than the cold and warm seasons of higher
latitudes.
The sun crosses the equator twice a year during
the equinoxes, causing two wet seasons each
year.
During the winter and summer solstice, the
tropics have their two dry seasons, when the
sun is more north or south of the equator.
Further from the equator, the two wet seasons
merge into one, and the climate becomes more
monsoonal, with one wet season and one dry
season.
In the Northern Hemisphere, the wet season
is from May to July, and in the Southern Hemisphere
from November to February.
Next week, we’ll explore Tropical Cyclones.
