Troposphere

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.
The temperature decreases in this layer with the increase in height.
All the weather phenomena such as rainfall, hail, and fog occur here as the clouds are formed in this layer.
The upper limit of the troposphere is known as tropopause. The temperature may be as low as −58°C at this level.

Composition of the Atmosphere

The atmosphere is made of many gases and solid particles.
Nitrogen and oxygen are the two major gases which are present in the atmosphere.
Nitrogen makes up 78% of the total volume of the atmosphere. It is essential for the survival of plants. Plants cannot directly take in nitrogen from the atmosphere. The bacteria present in the soil and roots of plants convert it to a form which can be used by plants.
Oxygen is the second most available gas in the air. It is also known as the life-giving gas as it is inhaled by human beings and animals and is essential for their survival.
Gases such as argon, carbon dioxide and water vapour constitute the remaining one percent of the total volume of the atmosphere.
Carbon dioxide which is present in the atmosphere in small quantities is used by plants to make food. It absorbs the heat and keeps the Earth warm during the nights. The quantity of carbon dioxide remains constant in the atmosphere. However, its amount may increase because of the burning of fuels such as coal and oil. The increase in level of carbon dioxide adversely affects the weather and the climate of the Earth.
Water vapour is added to the atmosphere by the process of evaporation and transpiration from plants. All forms of precipitation are caused by water vapour present in the atmosphere.
Many particles such as dust, pollen, ash produced from meteorites and smoke are also present in the atmosphere.