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Layers of Earth's Atmosphere
The Atmosphere of the Earth
The Earth is the only planet in the solar system with an atmosphere that can sustain life. The envelope-like gases that surround the earth provides the air that we breathe and protects us from the blasts of heat and radiation emanating from the sun. It warms the planet by day and cools it by the night time.
The Earth's Atmosphere is made up of a very thin layer of gases and these gases are known as air which surrounds the planet Earth and is retained by Earth's gravity. There would be no life on Earth without the atmosphere. The atmosphere protects life by creating pressure allowing water to exist on Earth’s surface and absorbing ultraviolet solar radiation, warming the Earth’s surface through heat retention and reducing temperature extremes between day and night.
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There are three major constituents of air which are nitrogen, oxygen, and argon.
Energy is transferred between the earth’s surface and the atmosphere via conduction, convection, and radiation.
Conduction, Convection and Radiation
Structure of The Atmosphere
From the highest to the lowest the five main layers are:
1. Exosphere – the outer layer of the Earth’s atmosphere.
700 to 10,000 km (440 to 6,200 miles)
This is the upper limit of our atmosphere. It extends from the top of the thermosphere to 10,000 km (6,200 mi). The exosphere is the region where the molecules from the atmosphere can overcome the pull of gravity and escape into space.
2. Thermosphere – the second highest layer of the Earth’s atmosphere.
80 to 700 km (50 to 440 miles)
The thermosphere starts just above the mesosphere. It extends to 600 km (373 mi) high. The Aurora and satellites occur in this area.
3. Mesosphere – the third highest layer of the Earth’s atmosphere.
50 to 80 km (31 to 50 miles)
The mesosphere starts just above the stratosphere and extends 85 km (53 mi) high. Meteors burn up in this layer.
4. Stratosphere – the second lowest layer of the Earth’s atmosphere.
12 to 50 km (7 to 31 miles)
The stratosphere starts just above the troposphere and extends to 50 km (31 mi) high. The ozone layer, which absorbs and scatters the solar ultraviolet radiation, is in this layer.
5. Troposphere – the lowest layer of the Earth’s atmosphere.
0 to 12 km (0 to 7 miles)
The troposphere starts at earth's surface and extends 8 to 14.5 km (5 to 9 mi). We live in this area. This part of the atmosphere is the most dense. Almost all the weather is in this region. Most clouds appear in this area mainly because 99% of the water vapor in the atmosphere is found here in the troposphere.
Layers of the Atmosphere Photo
Properties of the Atmosphere
There is a thin envelope of air that surrounds our planet and it is a mixture of gases, each with its own physical properties. The mixture is far from evenly divided. Two elements, nitrogen, and oxygen make up 99% of the volume of air. The other 1% is composed of "trace" gases, the most prevalent of which is the inert gaseous element argon. The rest of the trace gases, although present in only minute amounts is very important to life on earth. Two, in particular, carbon dioxide and ozone, can have a large impact on atmospheric processes.
Another gas, water vapor, also exists in small amounts. It varies in concentration from being almost non-existent over desert regions to about 4% over the oceans. Water vapor is important to weather production since it exists in gaseous, liquid, and solid phases and absorbs radiant energy from the earth.
Processes of the Atmosphere
As we learned that water is an essential part of the earth’s system. Three-quarters of the earth’s surface are covered by water. It is important in exchanging the heat and the moisture in the atmosphere.
The cycles are as follows:
1. Most of the water vapor in the atmosphere comes from the oceans.
2. Most of the precipitation falling over the land finds it way back to the oceans.
3. About two-thirds returns to the atmosphere via the water cycle.
The oceans and the atmosphere interact extensively. The oceans act as a moisture source and a heat source for the atmosphere and a sink (storage).
Earth's Energy Budget Photo
Heat and Moisture Effects The Atmosphere
The heat and moistures profound effects on the atmospherics processes near and over the oceans. The ocean currents play a significant role in transferring this heat poleward. The northward flowing Gulf Stream, which is a major current transport tremendous amounts of heat poleward and also contributes to the development of many types of weather phenomena.
The northward Gulf Stream also helps to warm the climate of nearby locations. The cold southward flowing currents, for example, California’s current help to cool the climate of nearby locations.
Almost all of the energy that reaches the earth comes from the sun. It is intercepted firstly by the atmosphere. Then a small part of the energy is absorbed by certain gases such as the ozone and water vapor. Some of the energy is reflected back to space by the clouds and the earth’s surface.
Heat In Clouds Photo
Climate and Weather
Earth is able to support a wide variety of living beings because of its diverse regional climates, which range from extreme cold at the poles to tropical heat at the Equator.
The global climate has cooled and warmed throughout history.
Climate and Weather Photo
© 2017 Elizabeth J Neal