From satellite it looks like this:

The tropics (or ITCZ) is a region of heavy rainfall in the tropics. In contrast, the subtropics are arid and cover the world's major desert regions (e.g. the Sahara).

Rainfall is among the most complex atmospheric fields as it depends on a variety of meteorological variables including winds, humidity, and temperature. Rainfall is also highly variable temporally as you can tell from this time series.