The document describes the structure and composition of Earth's atmosphere. It is divided into four main layers based on temperature - the troposphere, stratosphere, mesosphere, and thermosphere. The troposphere contains around 90% of the atmosphere's mass and is where weather occurs. Above this is the stratosphere, where temperature increases with altitude due to ozone absorbing UV light. The mesosphere is the coldest region and the thermosphere contains extremely high temperatures but little heat due to solar radiation. The atmosphere also protects the surface from radiation through the ozone and ionosphere layers.

1. The Atmosphere Structure and Change