The thermosphere lies above the mesosphere.
- Thermosphere extends to a height of about 640 km.
- In this layer temperature rises dramatically, reaching up to 1480°C.
- This increase in temperature is due to the fact that the gas molecules in this layer absorb the X-rays and ultraviolet radiation of the Sun.
- This results in the break up of the gas molecules into positively and negatively charged particles or ions. Thus, this layer is also known as the ionosphere.
- The electrically charged gas molecules of the thermosphere reflect radio waves from the Earth back into space. Thus, this layer also helps in long-distance communications.
- The thermosphere also protects us from meteors and obsolete satellites, because its high temperature burns up nearly all the debris coming towards the Earth.
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.
Also, Read The Atmosphere