Rainfall Types

Rainfall Types

https://www.s-cool.co.uk/gcse/geography/weather-and-climate/revise-it/rainfall-types

3 types of Rainfall:

• conventional 

• frontal

• relief 

Convectional rainfall occurs when:

• The surface of the earth is heated by the sun.

• The warm surface heats the air above it. Hot air always rises so this newly heated air does so.

• As it rises the air-cools and begins to condensate.

• Further rising and cooling causes a large amount of condensation to occur and rain is formed.

• Convection tends to produce towering cumulonimbus clouds, which produce heavy rain and possible thunder and lightning.

Frontal rainfall occurs when:

• Two air masses meet, one a warm air mass and one a cold air mass.

• The lighter, less dense, warm air is forced to rise over the denser, cold air.

• This causes the warm air to cool and begin to condense.

• As the warm air is forced to rise further condensation occurs and rain is formed.

• Frontal rain produces a variety of clouds, which bring moderate to heavy rainfall.

Relief Rainfall occurs when:

• The prevailing winds pick up moisture from the sea as they travel across it, making the air moist.

• The moist air reaches the coast and is forced to rise over mountains and hills.

• This forces the air to cool and condense, forming clouds.

• The air continues to be forced over the mountains and so it drops its moisture as relief rain.

• Once over the top of the mountain the air will usually drop down the other side, warming as it does so. This means it has a greater ability to carry water moisture and so there is little rain on the far side of the mountain. This area is called the rain shadow