Convectional rainfall occurs when the warm air deflected from a landform rises and forms rain clouds. Convectional rainfall is very common in tropical areas as well as areas in southeastern England.
When the sun's warm rays heat the land, it also heats the air above it. The warm air will cool as it rises. During condensation, clouds form and produce rain. The type of clouds formed during the convection process are known as cumulonimbus clouds. The storms caused by the convection process are known as air-mass storms, and they only cover a small portion of land. Frontal thunderstorms will affect a much larger region. Convectional storms occur in many different geographic locations, but are more severe in tropical areas where water sources are abundant and climates are warmer. They are also more severe in warmer mountain regions