Types of Rainfall | Convectional, Orographic, and Cyclonic

Rainfall occurs when water vapor in the air condenses to form clouds, and the water droplets become too heavy to remain suspended, eventually falling to the ground. There are 3 major types of rainfall:

1. Convectional rainfall
2. Orographic (or relief) rainfall
3. Cyclonic (or frontal) rainfall

Types of Rainfall

1. Convectional rainfall

• When the sun heats the Earth’s surface, water evaporates and forms water vapor.
• The warm, moist air rises in convective currents. As the air rises, it cools, and the water vapor condenses to form clouds.
• The clouds grow and when the condensed water droplets become too heavy, rainfall occurs.
• The rainfall is often accompanied by thunder and lightning.
• Convectional rainfall is common in tropical regions, where intense heating occurs regularly. In temperate regions, it usually happens during the summer months.

2. Orographic (or relief) rainfall

• When a warm, moist air current approaches a mountain, it is forced to rise up the slope.
• As it rises, the air cool and condenses, forming clouds.
• These clouds bring rain, most of which falls on the ridge facing the air current (windward side).
• The other side (known as the leeward side) receives significantly less rainfall.
• The area on the leeward side is called the rain shadow region.

(Also read: How is rainfall measured? | What does 1 mm rainfall mean?)

3. Cyclonic (or frontal) rainfall

• It occurs when two air masses with different temperatures collide.
• The colder air mass being denser stays closer to the surface while the warmer air mass rises above it.
• As the warm air rises it cools and condenses to form clouds that produce rainfall.

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