Atmosphere of Earth    

The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, greenhouse effect, and reducing temperature extremes between day and night. The study of Earth's atmosphere and its processes is called atmospheric science (aerology).

The Different Levels of the Atmosphere are:

Troposphere: This is the lowest atmospheric layer and is about seven miles (11 km) thick. Most clouds and weather are found in the troposphere. The temperature decreases with altitude.

Stratosphere: The stratosphere is found from about 7 to 30 miles (11-48 kilometers) above the Earth’s surface. It lies above the troposphere and is separated from it by the tropopause. In this region of the atmosphere is the ozone layer, which absorbs most of the harmful ultraviolet radiation from the Sun. The temperature increases slightly with altitude in the stratosphere. The highest temperature in this region is about 32 degrees Fahrenheit or 0 degrees Celsius.

Mesosphere: The mesosphere is above the stratosphere. Here the atmosphere is very rarefied, that is, thin, and the temperature is decreasing with altitude, about –130 Fahrenheit (-90 Celsius) at the top.

Thermosphere: The thermosphere starts at about 55 kilometers. The temperature is quite hot; here temperature is not measured using a thermometer, but by looking at the motion and speed of the rarefied gases in this region, which are very energetic but would not affect a thermometer. Temperatures in this region may be as high as thousands of degrees.

Exosphere: The exosphere is the region beyond the thermosphere.

Ionosphere: The ionosphere overlaps the other atmospheric layers, from above the Earth. The air is ionized by the Sun’s ultraviolet light. These ionized layers affect the transmittance and reflectance of radio waves. Different ioniosphere layers are the D, E (Heaviside-Kennelly), and F