Question

What is the atmosphere? Write about its different layers.

Answer 1

Hint: The atmosphere is composed of many different gases. These gases also differ in their amount. There are permanent gases whose percentages do not change very rapidly such as nitrogen, oxygen and argon.

Complete answer: The word atmosphere comes from a Greek word ‘atmos’ which means vapour and ‘sphaira’ which means sphere or ball. The atmosphere is formed by layers of gases that surround the Earth. All of these are held together because of gravity. It contains various gases, most of them are in small amounts. The most abundant gas present in the atmosphere is nitrogen. It comprises 78 per cent of the total atmosphere. Oxygen amounts to 21% and argon amounts to 0.9%. Gases like carbon dioxide, nitrous oxides, methane, and ozone are about one-tenth of one percent of the atmosphere. The concentration of water vapour varies from 0-4% depending on one’s location and time. The concentration of water vapour in the atmosphere helps to predict the weather conditions.
A very common yet essential phenomenon of the atmosphere is its stratification. It has five major layers. These are the exosphere ranging from 700 to 10,000 km, the thermosphere ranging from 80 to 700 km, mesosphere ranging from 50 to 80 km, stratosphere ranging from 12 to 50 km and troposphere ranging from 0 to 12 km. The lowest layer is the troposphere.

Note: There is an ozone layer where the concentrations of Ozone are about 2 to 8 parts per million. The ionosphere is another layer which is a region that is ionized by solar radiation and is responsible for auroras in the atmosphere.