Describe the layers of Earth's atmosphere.
The Earth's atmosphere is divided into five primary layers based on temperature variations. From closest to Earth to farthest, these layers are: troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
1. Troposphere: This is the layer closest to the Earth's surface and extends approximately 7 to 20 kilometers above it. It contains almost 75% of the atmosphere's mass and is where weather phenomena occur. As you move up through the troposphere, the temperature decreases.
2. Stratosphere: Above the troposphere lies the stratosphere, extending from about 20 to 50 kilometers above the Earth's surface. The stratosphere contains the ozone layer, which absorbs most of the sun's harmful ultraviolet radiation. Temperature increases with height in this layer due to the absorption of sunlight.
3. Mesosphere: The mesosphere extends from the top of the stratosphere to around 85 kilometers above the Earth. In this layer, temperatures decrease again with height and can reach as low as -90 degrees Celsius. The mesosphere is known for its occurrence of meteoroids burning up as they enter the Earth's atmosphere, creating shooting stars.
4. Thermosphere: The thermosphere spans from approximately 85 kilometers to 600 kilometers above the Earth. Temperatures rise significantly in this layer due to the absorption of high-energy solar radiation. However, despite high temperatures, this layer would feel cold to humans due to its extremely low density.
5. Exosphere: The exosphere is the outermost layer of the Earth's atmosphere, starting around 600 kilometers and extending outwards into space. This layer is composed of very few molecules and atoms which are released into space due to their high energy. It merges seamlessly with the vacuum of space and lacks a defined upper boundary.
These layers play vital roles in regulating the Earth's climate, protecting life from harmful radiation, and facilitating various atmospheric phenomena.