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Layers of the Atmosphere

Shows the different layers of the atmosphere
This drawing shows the different layers of the atmosphere. The ground is shown in brown at the bottom of the picture. The altitude in kilometers is given on the right hand scale and is approximate. (Click for a larger image.) © UC Regents

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 troposphere is thinner at the poles (averaging about 8km thick) and thicker at the equator (averaging about 16km thick). The temperature decreases with altitude.

Stratosphere: The stratosphere is found from about 7 to 30 miles (11-48 kilometers) above the Earth’s surface. 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 (Appleton) regions.

Shows the penetration of different kinds of electromagnetic radiation into the atmosphere
This drawing shows the penetration of different kinds of electromagnetic radiation into the atmosphere. Note also the different layers of the ionosphere (D, E, F) and the level at which auroras occur.(Click for a larger image.) © UC Regents

Starting at the left:
Lightning can generate whistlers, radio waves that can travel long distances. Very high frequency radio waves (VHF) can travel through the atmosphere to and from satellites and are used for communication. The airglow is due to a chemical reaction in the upper atmosphere that emits light. Many radio waves are reflected at night by the ionosphere making it possible to hear AM radio and shortwave radio stations that are far away. Gamma rays and x-rays are absorbed by the upper atmosphere; visible light can penetrate to sea level. Many infrared wavelengths can also pass through the atmosphere.

Related to chapter 3 in the print guide.
Related Materials
See Scientific Ballooning to learn how scientists use balloons for research.
Glossary Terms

Click for the definitions of the following words that are used on this page: (Definitions appear in a pop-up window.)

cosmic rays
ultraviolet radiation
white light

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