Types of Precipitation
Types of PrecipitationDepending on the Geo-Physical condition and the regional variation in the climatic condition, there is different types of precipitation.
- It is caused by a conventional ascent of warm and humid air to great heights. Most of it is in the form of rainfall.
- Due to excessive heating of the earth's surface in summer months, vertical air currents are, produced.
- As the surface air rises, it expands and cools and eventually gets saturated. This is followed by condensation and precipitation.
- Convectional precipitation is heavy but highly localized and is associated with a minimum amount of cloudiness.
- Rainfall in the doldrums is of convectional nature.
- It occurs when warm and humid air strike landform barriers such as mountain ranges and are forced to rise.
- In orographic precipitation, the windward slope of a mountain range gets more precipitation than the leeward slope because the air descends down the slope and gets warmed up. Hence, the leeward slope is drier and is known as the rain-shadow area.
Cyclonic or Frontal Precipitation
- When precipitation is associated with a cyclonic circulation, it is called Cyclonic or Frontal Precipitation
- When warm or humid air mass converges with the cold air mass, they cause turbulent and stormy conditions, generally followed by precipitation particularly along their fronts.
Distribution of Precipitation
- Different places on the earth's surface receive different amounts of precipitation in a year, and that too, in different seasons.
- High latitudes having the high pressure associated with subsiding and diverging winds, experience rather dry conditions.
- The equatorial belt with low pressure and its converging winds, and ascending air receives ample precipitation.
- Cold air has low capacity to hold moisture than the warm air, a general decrease in precipitation is revealed with the increasing distance of latitude from the equator towards the poles.
- Large land masses in the middle latitudes generally experience a decrease in precipitation towards their interiors.
- Windward mountain slopes receive abundant precipitation, while leeward slopes and adjacent low lands fall in rain-shadow.
- The equatorial belt, the windward slopes of the mountains along the western coasts in the cool temperate zone and the coastal areas of the monsoon lands, receive' heavy precipitation of over 200 centimetres per annum.
- Areas adjacent to the high precipitation regime receive moderate rainfall varying from 100 to 200 centimetres per annum.
- The central parts of the tropical land and the eastern and interior parts of the temperate lands receive inadequate precipitation varying between 50 to 100 centimetres per annum.
- Areas lying in the rain-shadows, the interior of the continents and high latitudes receive low precipitation i.e. less than 50 centimetres per annum
- In some regions, precipitation is distributed evenly throughout the year such as in the equatorial belt and the western parts of cool temperate regions.
- Some of the regions such as monsoon lands and the Mediterranean regions experience seasonal rainfall.