The Earth’s atmosphere is composed of five distinct layers, each defined by temperature gradients and varying composition. These layers are:
- Troposphere: This is the lowest layer of the atmosphere, extending from the surface up to about 8-15 kilometers (5-9 miles) high. It is where most weather phenomena occur, and temperature decreases with altitude. The troposphere is defined by the presence of clouds, rain, and the air we breathe.
- Stratosphere: Above the troposphere lies the stratosphere, reaching about 50 kilometers (31 miles) above the Earth. This layer contains the ozone layer, which absorbs harmful ultraviolet (UV) radiation from the sun. In this layer, temperature increases with altitude, a phenomenon known as temperature inversion.
- Mesosphere: The mesosphere extends from the top of the stratosphere to about 85 kilometers (53 miles) above the Earth. Here, temperatures decrease with altitude, making it the coldest layer of the atmosphere. It is also where most meteoroids burn up upon entering the Earth’s atmosphere.
- Thermosphere: This layer stretches from approximately 85 kilometers (53 miles) to about 600 kilometers (373 miles) above the Earth. In the thermosphere, temperatures rise dramatically with altitude, and can reach up to 2,500°C (4,500°F) or higher due to the absorption of high-energy solar radiation. The auroras occur in this layer.
- Exosphere: The exosphere is the outermost layer of the Earth’s atmosphere, extending from about 600 kilometers (373 miles) to 10,000 kilometers (6,200 miles). It is where the atmosphere gradually fades into space. The density is extremely low, and the particles in this layer can travel hundreds of kilometers without colliding with one another.
In summary, these layers are defined by their altitude, temperature changes, and the processes that occur within them. Understanding these distinctions helps us to grasp how the atmosphere protects us and affects our weather and climate.