RAINFALL

RAINFALL

WHAT IS RAINFALL?

• The precipitation in the form of water droplets is called rainfall.
•  In low latitudes, rain is the most common form of precipitation.

WHAT ARE TYPES OF RAINFALL?

• Rainfall classified into three main types on the basis of origin:

• Convectional
• Orographic or Relief
• Cyclonic or Frontal

WHAT IS CONVECTIONAL RAINFALL?

• The air becomes light on heating and rises.
• As the air rises, condensation takes place and cumulus clouds are formed.
• It is heavy rainfall but of short duration.
• Minimum number of clouds formed.
• It occurs mainly during summers.
• It is common in the Congo basin and the Amazon basin.

WHAT IS OROGRAPHIC OR RELIEF RAINFALL?

• It occurs due to the accent of air from highland.
• The rising air expands, the temperature falls and the moisture gets condensed.
• The chief characteristic is that the windward slopes receive greater rainfall.

• When these winds reach the other slope, they descend and temperature rises.
• Their capacity to take moisture increases, these leeward slopes remain rainless and dry.
• The area situated on the leeward side gets less rainfall, known as the rain-shadow area.
• Mahabaleshwar receives >600 cm rainfall, while Pune lying in the rain shadow area has about 70 cm.

WHAT IS CYCLONIC RAINFALL?

• It occurs due to the upward movement of air.
• Cyclonic activity causes cyclonic rain along its fronts.
• When two different air masses meet then it is formed.
• This rain falls gradually from few hours to a few days.

WHAT IS MONSOON RAINFALL?

• This type of rainfall is characterized by seasonal reversal of winds which carry moisture from oceans
• The south-west monsoon occurs with this method.
•  This rainfall happens in south and southeast Asia.