The document describes the layers of Earth's atmosphere: - The troposphere is the lowest layer where weather occurs and contains 75% of the atmosphere's mass. It extends from Earth's surface to around 12 km. - The stratosphere is above the troposphere, extending from around 12 km to 40-48 km. Temperature remains constant or increases with height due to ozone absorption. - The mesosphere is the coldest layer, reaching -95°C, located from 40-48 km to 80-96 km. It contains noctilucent clouds.

2. Troposphere
Stratosphere
Mesosphere
Thermosphere

3. This is the lower part and most dense layer of the
atmosphere.
Most of the turbulence occurs in this layer, all clouds,
precipitation, and storms are developed.
The troposphere is wider at the equator about lower
10 to 12 km or 6 to 8 mi. than at the poles with 5 to 8
km or 5 mi.
The air temperature falls until -55º C at the upper
boundary at about 12.8 km, known as the tropopause,
in middle latitude.

5. It contains 75 percent of the Atmosphere’s mass- on
an average day the weight of the molecules in air is
1.03 kg./sq. cm. and most of the atmosphere’s water
vapor.
The most prevalent gases are nitrogen(78%) and
oxygen(21%), with the remaining (1%) for argon,
traces of hydrogen, ozone, methane, and other
constituents.
A common feature of the troposphere of densely
populated areas is SMOG.

6. Upper layer of the atmosphere commencing at an
altitude of 24 km and extending upward to about 40-
48km.
In the lower portion of the stratosphere, the
temperature remains nearly constant with height, but
in the upper portion the temperature increases
rapidly with height about -10ºC because of absorption
of sunlight by ozone.
The stratosphere is almost completely free of clouds
or other forms of weather.

9. The coldest layer of the atmosphere with altitude to
about -95ºC at the upper boundary of 80-96 km
altitude, known as mesopause.
On this region where the lowest temperature in the
atmosphere is found.
The presence of “Noctilucent Clouds” is a high
distinguishing feature of this layer.
The air temperature decreased with height.

13. 80 km. and up. The air is very thin.
Thermosphere means heat sphere.
The temperature on this layer is very high because the
ultraviolet radiation is turned into heat.
Temperature often reach 2000 degree Celsius or
more.
This layer contains IONOSPHERE, and EXOSPHERE.

15. It is the lower part of the thermosphere.
It extends from about 80km to 550 km.
The particles of gas become electrically charged
(ions). Radio waves are bounced off the ions and reflect
waves back to earth. This generally helps radio
communication. However, solar flares can increase the
number of ions and can interfere with the transmission
of some radio waves.

16. The upper part of the Thermosphere.
It extends from about 550 km for thousands of
kilometers.
The air is very thin here.
This is the area where satellites orbit the earth.