|WHY IS ITCZ MEAN POSITION|
NORTH OF THE EQUATOR?
METEOROLOGIST JEFF HABY
ITCZ stands for Intertropical Convergence Zone. It is a region of clouds, rain,
low level convergence
and rising air. Portions of the tropics that have a wet season have the wet season when the ITCZ is
overhead or nearby.
The ITCZ is a global belt of low pressure produced by the convergence of air coming out of the high
pressure belt to the north and the high pressure belt to the south. The portions of the tropics
dominated by high pressure have very dry weather and many of the world's deserts are located under
The ITCZ shifts position over the course of the year since the sun's direct rays on the earth vary over
the course of a year. The ITCZ tends to be located under and near where the sun's rays are most
direct. Thus, the ITCZ will be located north of the equator in the Northern Hemisphere summer and
south of the equator in the Northern Hemisphere winter. However, the mean or average position of the
ITCZ is located north of the equator.
The ITCZ has a mean position north of the equator because there is much more landmass in the Northern
Hemisphere as compared to the Southern Hemisphere. Look at a globe and notice how much more land there
is in the tropics in the Northern Hemisphere. Land heats more than water. When the land surface
is warmer than the water it promotes a large scale
sea breeze (flow from ocean toward the land). This
produces a convergence of air over the land. Areas such as S.E. Asia have heavy rain
in the summer due to this circulation. The ITCZ has its most northerly displacement in the summer
over Asia due to the large landmass of Asia to the north of the equator.