The document discusses three main types of rainfall: relief, convective, and frontal. Relief rainfall occurs when air is blown over the sea and then forced up over high land, causing the air to cool and condense into rain. Convective rainfall primarily happens in tropical areas where hot air rises, cools, and forms rain or thunderstorms. Frontal rainfall occurs at the boundary of warm and cold air masses, where the warm air is forced to rise over the cold air, cooling and condensing into rainclouds and precipitation. Diagrams and descriptions are provided for each type of rainfall.