The Five Layers of Earth's Atmosphere | Science
In a recent high emphasis TASC Test Assessing Secondary Completion™ Science post, we discussed how Earth’s atmosphere supports life. To complete our study of the atmosphere, this post will explore the five atmospheric layers.
The atmosphere begins at the Earth’s surface. From there, the atmosphere extends outward, becoming increasingly thin until it merges with space. Let’s take a deeper look at each layer:
The troposphere starts on Earth’s surface and extends nine miles outward. With almost all water vapor and dust particles existing in this range, clouds and weather patterns are capable of forming in this layer. The higher in altitude you travel in the troposphere, the cooler the temperature becomes.
Absent of clouds, the stratosphere begins after the troposphere and extends 31 miles above Earth’s surface. According to Space.com, air in the stratosphere is approximately one thousand times thinner than at sea level. The thin air allows aircraft and weather balloons to fly in this layer. The ozone – the covering that heats the atmosphere and absorbs the sun’s harmful ultraviolent radiation – is also in this layer.
Following the stratosphere, the mesosphere stretches 51 miles above Earth’s surface. This is the hardest layer for scientists to study since aircraft and weather balloons don’t fly high enough, and space shuttles and satellites orbit too high. Scientists do know that meteors burn up in this layer, and the top part of the mesosphere – called the mesopause – is the coldest part of the atmosphere, averaging -130° F.
Succeeding the mesosphere, the thermosphere reaches an average of 372 miles above Earth’s surface. The International Space Station and satellites orbit the Earth in this layer; auroras, such as the Aurora Borealis, also occur in this layer.
The exosphere is the uppermost part of the atmosphere and completes the merge with outer space. It’s nearly 6,200 miles away from the Earth’s surface. The thinnest of the five layers, the exosphere is composed of widely dispersed particles of helium and hydrogen.
Continue your practice for the TASC test by taking our quiz on the Earth’s atmosphere.