Earth’s atmosphere stretches from the surface of the planet up to as far as 10,000 kilometers (6,214 miles) above. After that, the atmosphere blends into space. The atmosphere is divided into five different layers, based on temperature. Let’s read about the atmospheric layers in detail…
Troposphere: Earth’s surface to between 8 and 14 kilometers. It’s thinnest above the poles, just 8 kilometers (5 miles) or so. The troposphere holds nearly all of Earth’s water vapour. It’s where most clouds ride the winds and where weather occurs. It contains as much as 80 percent of the mass of the whole atmosphere. The further up you go in this layer, the colder it gets. The boundary between the troposphere and the next layer up is known as the tropopause.
Stratosphere: It ranges from 14 to 64 km of earth’s surface. Unlike the troposphere, temperatures in this layer increase with elevation. The stratosphere is very dry, so clouds rarely form here. It also contains most of the atmosphere’s ozone, triplet molecules made from three oxygen atoms. At this elevation, ozone protects life on Earth from the sun’s harmful ultraviolet radiation. It’s a very stable layer, with little circulation. For that reason, commercial airlines tend to fly in the lower stratosphere to keep flights smooth.
Mesosphere: 64 to 85 km. Scientists don’t know quite as much about this layer. It’s just harder to study. Airplanes and research balloons don’t operate this high and satellites orbit higher up. We do know that the mesosphere is where most meteors harmlessly burn up as they hurtle towards Earth. Near the top of this layer, temperatures drop to the lowest in Earth’s atmosphere — about -90° Celsius (-130° Fahrenheit). The line marking the top of the mesosphere is called, you guessed it, the mesopause.
Thermosphere: It ranges from 85 to 600 km of Earth’s surface. The next layer up is the thermosphere. It soaks up x-rays and ultraviolet energy from the sun, protecting those of us on the ground from these harmful rays. The ups and downs of that solar energy also make the thermosphere vary wildly in temperature. It can go from really cold to as hot as about 1,980 ºC (3,600 ºF) near the top.
The sun’s varying energy output also causes the thickness of this layer to expand as it heats and to contract as it cools. The International Space Station orbits Earth at an average altitude of about 400 kilometers (in thermosphere). Satellites also operate in this region and higher, into the exosphere.
Exosphere: It ranges from 600 to 10,000 km of Earth’s surface. The uppermost layer of Earth’s atmosphere is called the exosphere. Its lower boundary is known as the exobase. The exosphere has no firmly defined top. Instead, it just fades further out into space. Air molecules in this part of our atmosphere are so far apart that they rarely even collide with each other. Earth’s gravity still has a little pull here, but just enough to keep most of the sparse air molecules from drifting away.