Why are rain showers common near the ITCZ?
The inter-tropical convection zone is the hottest place on earth since it is on both sides of the equator; the place where the sun is the highest in the sky and the insolation is also highest. Warm air rises. As it does, moisture in the air condenses due to the adiabatic cooling of a lesser pressure aloft. It is then normal that the ITCZ is a wet place and this is where we, incidentally, find the rain forests around the earth. But why rain showers, rather than continuous rain? Well, it is complex but, in a nutshell, the tropical zone is more subject to unstable air masses and this is where you find thunderstorms, with gusty wind and rain showers. The weather in our atmosphere is limited to the troposphere where temperature sinks with altitude. The top of the troposphere is called the tropopause but that varies much from the poles to the equator because warmer air takes more place than denser, colder one. The tropopause is about 10 km high over the poles but 17 km high over the equator.
