Types of rainfall

Rainfall occurs when the condensed water vapor from the clouds falls on Earth in the form of droplets. There are 3 major types of rainfall.

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Types of rainfall

Convectional Rainfall

  • When the sun heats the Earth’s surface, the water evaporates to form water vapor.
  • The warm moist air then rises in a convective current. As the air rises, it cools and the water vapor condenses to form clouds.
  • The clouds grow and eventually rainfall occurs as the weight of condensed water increases.
  • The rainfall is often accompanied by thunder and lightning.
  • Convectional rainfall in common in tropical regions while in temperate regions, it occurs mainly during the summers.

Orographic or relief rainfall

  • When a warm moist air current approaches a mountain, it rises up the slope and cools, consequently forming clouds.
  • These clouds bring rain, most of which falls on the ridge facing the air current (Windward side).
  • On the leeward side, the rainfall is very less.
  • The area on the leeward side is also known as the rain shadow area.

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 which bring rain thereafter.

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