Frontal rainfall occurs when the warm and the cold air meet each other.
- This type of rainfall occurs when the warm and the cold air meet each other. Because the warm air is lighter, it rises above the cold air. The rising air is then cooled beyond the saturation point resulting in heavy rainfall.
- Such rainfall lasts only for few hours. It is very heavy during tropical cyclones.
Thunderstorms are associated with heavy rainfall and lightning
- Lightning is caused when raindrops move up and down because of convectional air currents.
- Because the temperature above the clouds is extremely low, small ice particles are formed.
- When these ice particles move against each other, they become electrically charged. While positively charged ions (which are lighter) settle at the top of the cloud, the negatively charged ions settle at the bottom of the clouds.
- When positively and negatively charged ions are attracted towards each other, a flash of lightning takes place.
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Various forms of Precipitation are 1. Rain: It is the most common form of precipitation. The droplet of water that precipitates from clouds is known as rainfall.
Evaporation changes the water from the liquid form to the gaseous form. Water vapour which is present in the atmosphere is known as humidity.
The exosphere is the uppermost layer of the Earth. Light gases such as helium and hydrogen float into space from this layer because of the lack of gravity.
The mesosphere is the third layer of the atmosphere and it lies above the stratosphere up to the height of 80 km. It is in this layer that the meteorites burn when they enter the atmosphere from space.
The thermosphere lies above the mesosphere. This layer extends to a height of about 640 km. In this layer temperature rises dramatically, reaching up to 1480°C.
The troposphere is the most important layer of the atmosphere. It extends up to 13 km from the surface of the Earth. The oxygen which we breathe exists in this layer of the Earth.