The next region, called the stratosphere, increases as you move higher! The section in between the troposphere and stratosphere is called the tropopause. The temperature doesn't change in this area.
The stratopause is just above the stratosphere, and next is the mesosphere. The mesosphere is like the troposphere, the temperature gets colder as you move up. Finally, there is the mesopause and then the thermosphere. The thermosphere is like the stratosphere, it get hotter as you move up!
So you see, the temperature changes a lot as you move higher. This is why there can be snow on top of a mountain even in the summer. Because at the top of the mountain it is still very cold!
Most people know that it is colder on top of a mountain compared to the ground, but few actually know why. And even less know that the atmosphere actually warms up again! The true temperature profile of the atmosphere is shown in the image.
The air at the surface up to around 10 kilometers is called the troposphere. The reason it is warmer at the surface is simple. The air is warmed by heat given off by the Earth! The farther away from the surface the air moves, the less heat there is to absorb.
From 10 to 20 kilometers the atmosphere is stable. This region is called the tropopause. From 20 to about 50 kilometers is the stratosphere. In this region the air actually warms with height! Ozone is concentrated in this part of the atmosphere and it absorbs ultraviolet light from the Sun. More light is absorbed at higher altitudes compared to the lower stratosphere, so the temperature increases.
But at 50 kilometers, the temperature levels out again in a region called the stratopause. At about 55 km, the mesosphere begins. In the mesosphere, the temperature decreases with height again, because there is very little ozone to warm up the air.
Finally, the mesopause divides the mesosphere from the thermosphere, which is the section of the atmosphere higher than 90 km. In this region, the temperature increases again! This time, it is molecular oxygen (O2) that causes the temperature increase. The oxygen absorbs light from the Sun, and since there is very little air in the thermosphere, just a little absorption can go a long way!
Most people know that it is colder on top of a mountain compared to the ground, but few actually know why. And even less know that the atmosphere actually warms up again! The true temperature profile of the atmosphere is shown in the image.
The air at the surface up to around 10 kilometers is called the troposphere. The name comes from the Greek word tropein, which means to turn or change. The troposphere is very well mixed, because the air near the surface is warmer than the air above it. So, like a pot of boiling water, the warmer air is always rising. The reason it is warmer at the surface is simple. The air is warmed by radiation emitted by the Earth! The farther away from the surface the air moves, the less radiation there is to absorb.
From 10 to 20 kilometers the atmosphere is stable. This region is called the tropopause. From 20 to about 50 kilometers is the stratosphere. In this region the air actually warms with height! Ozone is concentrated in this part of the atmosphere and it absorbs ultraviolet light from the Sun. More light is absorbed at higher altitudes compared to the lower stratosphere, so the temperature increases.
But at 50 kilometers, the temperature levels out again in a region called the stratopause. At about 55 km, the mesosphere begins. In the mesosphere, the temperature decreases with height again, because there is very little ozone to warm up the air. Like the troposphere, the mesosphere is well mixed because the warmer air below is always rising.
Finally, the mesopause divides the mesosphere from the thermosphere, which is the section of the atmosphere higher than 90 km. In this region, the temperature increases again! This time, it is molecular oxygen (O2) that causes the temperature increase. The oxygen absorbs light from the Sun, and since there is very little air in the thermosphere, just a little absorption can go a long way!
Scientists point out that this is just an average profile of the atmosphere. The arctic region will have a similar profil e to the tropics, but the heights of each layer and the actual temperatures will be different.
Last modified prior to September, 2000 by the Windows Team
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