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Layers of Earth's Atmosphere

The Earth's Atmosphere

The atmosphere surrounds Earth and protects us by blocking out dangerous rays from the sun. The atmosphere is a mixture of gases that becomes thinner until it gradually reaches space. The air in the atmosphere is essential to life because it allows us to breathe.
Recently, there have been many studies on the atmosphere connected to the greenhouse effect . The ozone layer has also been in the news a lot.

The atmosphere is divided into five layers depending on how temperature changes with height. Most of the weather occurs in the first layer.

Layers of the Earth's Atmosphere

There are five layers in the atmosphere. The atmosphere thins out until it reaches space.

  1. The troposphere is where weather occurs. You breathe the air in the troposphere.
  2. Many airplanes fly in the stratosphere because it is very stable. Also, the ozone layer is there.
  3. Many rock fragments from space burn up in the mesosphere.
  4. The thermosphere is very thin. It's where the space shuttle orbits.
  5. The upper limit of our atmosphere is the exosphere.

The Average Temperature Profile of Earth's Atmosphere

Temperature profile of Earth's atmosphere

The Troposphere

The troposphere is the lowest layer of the Earth's atmosphere. The temperature in the troposphere goes down as you go higher.

Weather occurs in the Earth's troposphere.

The Stratosphere

The stratosphere is the second layer of the atmosphere. The the temperature in the stratosphere goes up the higher you go up.

Ozone causes the temperature to go up. It absorbs dangerous light from the Sun and converts it to heat.

The stratosphere is located above the troposphere.

Ozone - An Overview

Have you ever heard of ozone? That's a word that shows up in the news a lot! Do you know what ozone is and why it is important in the Earth's atmosphere?

Ozone is made of three oxygen atoms (O3). You've probably heard of oxygen before -- it's part of the air we breathe. The oxygen that we breathe is made up of two oxygen atoms (O2). Add another oxygen atom, and you have ozone! When a lot of ozone is around, you would see it as a pale blue gas. Ozone is found in two different layers of the atmosphere, the stratosphere and the troposphere. Where we find ozone in the atmosphere determines whether we consider it to be "good" or "bad"!

In the troposphere, the ground-level or "bad" ozone is an air pollutant that damages human health and plants. It is a key ingredient in smog. In the stratosphere, we find the "good" ozone that protects life on Earth from the harmful effects of the Sun. The simple saying "Good up high and bad near by" sums up ozone in the atmosphere.

Ozone in the Stratosphere

Most of the ozone that we know about is found in the the stratosphere, the second layer of the Earth's atmosphere. Ozone forms a kind of layer in the stratosphere. This layer shields us from the Sun's ultraviolet light. This ultraviolet light can cause damage to people like giving them skin cancer or causing tissue damage to their eyes. Ultraviolet light can also be bad for plants and animals.

The ozone layer would be very good at its job of protecting Earth from too much ultraviolet radiation - that is, it would if humans did not contribute to things! Human-released chemicals are speeding up the breakdown of ozone, so that there are "holes" now in our ozone protection shield.

Scientists know about this problem. They have told governments around the world that they need to stop making and releasing these harmful chemicals that break down ozone in the stratosphere. Countries have started doing this, and scientists are hoping that this will eventually heal the "holes" that were made in the ozone shield.

The Mesosphere

The mesosphere is the third layer in the atmosphere. The temperature drops when you go higher, like it does in the troposphere. It can get down to -90C in the mesosphere. That's the coldest part of the atmosphere!

The mesosphere starts on top of the stratosphere. Sometimes you can see the mesosphere by looking at the edge of a planet.

The Thermosphere

The thermosphere is the fourth layer of the Earth's atmosphere. It is found above the mesosphere. The air is really thin that high up. The temperature changes with the solar activity. If the sun is active, temperatures in the thermosphere can get up to 1,500C or higher!

The Earth's thermosphere also includes the region called the ionosphere.

The Ionosphere

The ionosphere is a special part of the atmosphere. It is not a separate layer, but part of the thermosphere.

Different regions of the ionosphere make long distance radio communication possible by reflecting the radio waves back to Earth. It is also home to auroras.

Temperatures in the ionosphere just keep getting hotter as you go up!

Regions of the Ionosphere

The ionosphere is broken down into the D, E and F regions.

The D region is the lowest. Then comes the E region. The F region is the highest. You can see this in the picture below.

Layers of Earth's ionosphere

This image shows how the ionosphere is divided even further into layers: D, E, and F layers.

The Sun's Effect on the Ionosphere

The ionosphere is an invisible region found in the Earth's atmosphere. When the Sun is more active, the ionosphere is thicker.

So things like flares and coronal mass ejections will make the ionosphere thicker!

Penetration of Earth's atmosphere by solar radiationThis image shows how different types of solar radiation (x-rays to infrared radiation) penetrate into the Earth's atmosphere. It is this solar radiation that ionizes the upper atmosphere, creating the ionosphere.

The Exosphere

The last layer of the Earth's atmosphere is the exosphere. This is the area where atoms escape into space.

Last modified September 1, 2010 by Randy Russell.

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