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ATMOSHERE. The earth's atmosphere is a very thin layer wrapped around a very large planet. Two gases make up the bulk of the earth's atmosphere: nitrogen , which comprises 78% of the atmosphere, and oxygen , which accounts for 21%. Various trace gases make up the remainder.
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ATMOSHERE • The earth's atmosphere is a very thin layer wrapped around a very large planet. • Two gases make up the bulk of the earth's atmosphere: nitrogen, which comprises 78% of the atmosphere, and oxygen, which accounts for 21%. Various trace gases make up the remainder. • Based on temperature, the atmosphere is divided into four layers: the troposphere, stratosphere, mesosphere, and thermosphere.
TROPOSPHERE (0 – 12 km) • Tropo is a Greek word means turnor change • It begins at the surface and extends to between 7 km (23,000 ft) at the poles and 17 km (56,000 ft) at the equator • Contains 75% of the gases in the atmosphere. • The temperature drops about 6.5 degrees Celsius for every kilometer above the earth's surface.
Normal weather and clouds occur • Heating of the Surface creates warm air at surface • Warm air rises, but air expands as it rises and cools as it expands (Adiabatic cooling) • Heating + Adiabatic Cooling = Warm air at surface, cooler air above • Tropopause - located at the top of the troposhere. The temperature remains fairly constant here. This layer separates the troposphere from the stratosphere
STRATOSPHERE (12 – 50 km) • Latin word "stratus" meaning spreading out. • The temperature remains fairly constant (-60 degrees Celsius). • This layer contains the ozone layer. • Ozone(O3) acts as a shield for in the earth's surface. It absorbs ultraviolet radiation from the sun. This causes a temperature increase in the upper part of the layer.
About 90% of the ozone in our atmosphere is contained in the stratosphere. • It is mainly located in the lower portion of the stratosphere from approximately 15–35 km • The boundary between the mesosphere and the stratosphere, typically 50 to 55 km is named as stratopause.
MESOPHERE (50 – 80 km) • Greek word “meso" meaning middle. • The temperature drops in this layer to about -100 degrees Celsius. • This is the coldest region of the atmosphere. • This layer protects the earth from meteoroids. They burn up in this area. • The boundary between the thermosphere and the mesosphere is named as mesopause.
THERMOSPHERE (above 80 km) • Contains two regions namely, • Ionosphere • Exoshere • Thermosphere means "heat sphere". The temperature is very high in this layer because ultraviolet radiation is turned into heat. • Temperatures often reach 2000 degrees Celsius or more.
IONOSPHERE (80 – 550 KM) • Gas particles absorb ultraviolet and X-ray radiation from the sun. • 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.
EXOSPHERE (550 – 1000 km) • Contain free-moving particles • Air is very thin here. • This is the area where satellites orbit the earth.
MAGNETOSPHERE (above 1000 km) • The area around the earth that extends beyond the atmosphere. • The earth's magnetic field operates here. It begins at about 1000 km. • It is made up of positively charged protons and negatively charged electrons. • This traps the particles that are given off by the sun.