Relief rainfall Relief rainfall occurs when air has been blown over the sea and is then forced up over an area of high land. This causes the air to cool and the moisture in the air condenses and rain falls. Frontal rainfall Frontal rainfall occurs when warm air is forced to rise over cold air. The moisture in the warm air condenses as it cools which causes clouds and rain.
Convectional rainfall Occurs mostly in tropics where it is hot.
When air is hot is rises and cools and condenses forming rain. If the air is hot enough, it rises very quickly and can cause thunderstorms.