TYPES OF RAINFALL

TYPES OF RAINFALL

  1. Relief rainfall.
  2. Frontal rainfall.
  3. Convectional rainfall.
  4. Mechanism rainfall.
  5. Intensity rainfall.

RELIEF RAINFALL 

  • Relief rainfall can also be known as “Orographic rainfall”.
  • Orographic rain occurs because of the orogenies process, which basically is a mountain building process.
  • When crustal plates come horizontally, it either comes closer or they move apart or sometimes they slide past each other and mountains are formed when two crustal plates come closer in which one has to slide under the bigger plate, which makes the land surface to elevate and that’s how mountains are formed.
  • The key element of Orographic rain is mountains.
  • When warm air rises, it does not rise in a straight upward pattern because of the things that flow horizontally.
  •  Heat moves from the areas of higher temperature to areas of lower temperature. 
  • The top portion of the mountain heats up faster and also loses heat faster than the valley floor. 
  •  When the warm air the ocean rises due to evaporation, it moves towards the cold region.
  • Before the warm air reaches the troposphere, the mid air altitude the warm air gets attracted towards the colder region which is at the top of the mountain.
  • The warm air then starts to cool because the atmospheric pressure  decreases with altitude, as the warm becomes to cool the water vapour present in it starts to condense.
  • The clouds began to form and then rainfall occurs, as the air reaches the summit of the mountain  it begins to descends, while going along the slope of a mountain temperature falls and while coming down the temperature rises, automatically the air capacity to take in the moist increases because at warm temperature air can take more moisture.
  • There will be no rain at the other side of the mountain as it is called a rain-shadow area.
  • In orographic rain, warm air is makes to cool when rises to the high altitude like a mountain or a hill, as the warm air rises at the slope of the mountain it cools, condenses and forms rain.
  • The orographic rain is found in the western ghats of India as well as the Himalayas.
  • When air temperature effortlessly cools down it forms orographic or relief rainfall.
  • Relief rainfall or orographic rainfall is usually formed in hilly regions or mountains.
  • As the cloud of relief rainfall rises it cools down and condenses rainfall.
  • Shadow rainfall rainstorm a small amount of rainfall on the downside or sloppy side of the mountain or hill.
  • Over 1,600 mm of total rainfall has measured down the mountain region in a year.
  • After the rainfall it descends and warms the region.
  • Relief rainfall is measured up to 12,000 mm per year.

FRONTAL RAINFALL

  • Frontal rainfall is the result of surrounding extratropical cyclones.
  • Frontal rainfall forms when warm and tropical air meets cold air.
  • When the warm air rises it creates a saturation,causing rainfall.
  • When passing the frontal precipitation it causes warm and humid climate on the ground level surroundings.
  • The warm air in frontal rainfall is formed when it moves out the cold air.
  • Then cold frontal precipitation the air is more dense than warm.
  • Cyclonic rainfall is basically caused when two air masses of different temperatures meet.

CONVECTIONAL RAINFALL

  • The earth’s surface heats up by the sunlight, it causes water to evaporate and causes evaporation thus occurs the convectional rainfall.
  • Convectional rainfall or light convection is caused by convective clouds.
  • Convectional rainfall falls over a small region for a short amount of time period.
  • Convective clouds have restricted vertical and horizontal extent.
  • In the initial stage of convectional rainfall it rainstorm down the rainfall rapidly and changes its intensity as it moves forward.
  • Convection rainfall is also called as convectional current.
  • Convectional currents transfer heat energy from one place to another, it takes place between : gases,liquid and even in molten rocks.
  • You can find convectional current in earth’s mantle, where the heat of the magma is released upwards towards the lithosphere, then the convectional currents are found in the atmosphere, where sun heats the land surface, making the surrounding air warmer.
  • Warm air rises and reaches the troposphere which comparatively is cold.
  • Convectional rain occurs when the sun’s energy heats up the land surface, it also heats the surrounding air.
  • Warm air rises and the rising of warm air forms currents because of the transfer of heat energy.
  • Naturally when warm air rises the sky starts to lose heat and that’s how condensation takes place and clouds are formed, and when the clouds are formed subsequently rain takes place.
  • So, it all starts from warming of air which takes place in the summer season and the idol region would be the equatorial region, because the equatorial region receives sun rays throughout the year.It particularly takes place in the northern hemisphere because northern hemisphere has lot more land than the southern hemisphere.
  • In result the northern hemisphere heats up faster than the southern hemisphere during summer.
  • Convectional rain is very common in the interior part of the continent, because land heats faster than the water surface.
  • Convectional rainfall is divided into two forms : cumulonimbus rainfall and cumulus rainfall.
  • In cumulonimbus rainfall it causes a violent electrical storm.
  •  In cumulus rainfall it causes towering clouds over one another in the medium to high height ranges.
  • Cumulonimbus rainfall is incompetent of generate lighting and cause storms, tornadoes and many more severe distructive weather conditions.
  • Cumulus rainfall can take shape to cumulonimbus rainfall after a certain amount of time.

MECHANISM RAINFALL

  • Mechanism takes place when the air is saturated with the water vapor and cant handle the dense water vapour in gaseous form. 
  • Mechanism rainfall materializes when less dense moist air elevates through the atmosphere.

INTENSITY RAINFALL 

  • Intensity rainfall is estimated through the rain measurement and also by the advanced technology of weather radar.
  • Intensity  rainfall can be split up into categories: light rain, moderate rain and heavy rain.
  • Light rain can be defined as  the rainfall which can be measured rainfall trace between 2.5 mm per hour.
  • Moderate rainfall can be defined as the rainfall trace between 2.6 mm to 7.6 mm per hour.
  • Heavy rainfall can be defined as the rainfall trace between 7.6 mm per hour.

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