Discuss and draw the different components of atmosphere
Answers
The Earth's atmosphere is the mix of gases that surrounds the planet. The Earth's atmosphere contains many layers. The part of the atmosphere that contains all the clouds, the weather, birds and airplanes is actually only a thin layer when compared to the full size of the Earth. The radius of the Earth approaches 4000 miles, but even our best planes can only go as high as 10 miles. It seems like a long way when you look down, but compared to the whole Earth, it's nothing. Even the International Space Station only orbits at 200 to 255 miles above the Earth's surface.
Today we're going to peal the Earth's atmosphere like an orange, going through each layer one by one. Then we'll look at what the atmosphere is made of as a whole.
Layers of the Atmosphere
When you go from the surface of the Earth and work your way up, the air pressure gradually decreases. It isn't a sudden thing: there's no point where space officially starts. So if it's gradual, how can the Earth's atmosphere have layers?
When you go up a mountain, it gets colder. The higher you are above the Earth's surface, the colder it is. But this isn't true for the whole of the Earth's atmosphere. There are parts where temperature stays constant, and other parts where it even increases as you go up! These changes in what happens to temperature are a big part of how we distinguish between the layers of the Earth's atmosphere.
The Earth's atmosphere has five main layers. Listed from the bottom to the top, they are: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
The Layers of the Atmosphere
Radiant
The troposphere is the area that goes from the surface of the Earth to a height of 7.5 miles. This contains most of the clouds, weather, air planes, and air currents in the Earth's atmosphere. The exact height of the troposphere depends on where you are on the Earth, and the exact weather conditions at that moment. It contains around 80% of the mass of the atmosphere.
The stratosphere is just above the troposphere. It goes from 7.5 miles up to around 31-34 miles above the Earth's surface. Here you find a few unusually high clouds called nacreous clouds, the ozone layer, and even a few aircraft. The highest flying commercial aircraft we have, such as the Concorde, can fly in the lower parts of the stratosphere - as high as 11.4 miles (60,000 feet). The record for any jet aircraft is 23.4 miles (123,520 feet) and was set in 1977 by a Soviet pilot. The temperature in the stratosphere gets warmer as you go up due to the absorption of ultraviolet radiation in the ozone layer.
The mesosphere is above the stratosphere and reaches from around 31-34 miles above the ground up to 50-53 miles. Temperatures start to drop again, and it quickly becomes so cold that the tiny amounts of water vapor found there can sublimate straight into clouds. No clouds can form anywhere above the mesosphere.
The thermosphere is next, and goes from 50-53 miles up until 310-620 miles. The size of the thermosphere depends on how active the Sun is at any given time. Temperature here increases yet again, but it's not a very reliable way of measuring anything; there are so few molecules up here that the fact that they're moving faster doesn't really tell you much. There's still very little heat content. There are no clouds in this layer, but this is where you find the auroras that people see from Earth near the North and South poles. The International Space Station orbits in this layer as well.
Space Shuttle Endeavor - Showing the Layers of the Atmosphere (Blue Mesosphere, White Stratosphere, Red Troposphere)
Space Shuttle Endeavor - Showing the Layers of the Atmosphere
The exosphere is the top layer of the atmosphere. It goes from 440 miles to 6,200 miles above the Earth. This is where most satellites orbit the Earth, though only in the lower parts. You could argue that this part of the Earth's atmosphere is hardly atmosphere at all. There are very few molecules here, and they are only loosely bound to the Earth.
Components of the Atmosphere
The Earth's atmosphere is mostly nitrogen by volume: 78% to be exact. A further 21% of the atmosphere is the oxygen that we breathe, followed by 0.9% argon, and 0.04% carbon dioxide. The fact that there is so little carbon dioxide in the atmosphere shows you how powerful it is as a greenhouse gas. All of climate change is happening because of changes in a tiny percentage of the atmosphere - yet it's more than enough. The atmosphere also contains water vapor which can reach as high as 5% of the atmosphere in the wettest places, but is often much less significant.