The atmosphere is defined as the envelope of air present around the earth. These envelopes extend up to several kilometres in height. This atmosphere is divided into many layers. These layers are - the troposphere, stratosphere, mesosphere, thermosphere, and the last layer is the exosphere now, as we go higher density of layers decreases. The troposphere is the lowest layer that contains air, air comprises many gases such as nitrogen, oxygen, and other gases. Biotic components interact with the atmosphere to make an environment.The atmosphere contains ozone which protects us from harmful ultraviolet radiation.