The Atmosphere
Weather is the name given to all the things that happen in the layer of air called the atmosphere, which surrounds our planet. If you step outside and see what the weather is doing today - this is what we are talking about -everything from sunny days to freezing blizzards.
Our atmosphere is held in place by gravity and without it, we could not survive as it protects us from temperature extremes. During the day, the atmosphere blocks out dangerous rays from the Sun and at night it helps to keep the planet from getting too cold.
If you look up into the sky on a clear day, you can see the atmosphere stretching some 1,000 km (600 miles) above you. Meteorologists (people who study the science of weather) have divided the atmosphere into layers and it is the very lowest layer called the troposphere that gives us the air that we breathe and our weather.
Layers of the Atmosphere
As altitude increases, air temperature falls in the Troposhere, rises in the Stratosphere
(due to the ozone layer), falls again in the Mesosphere, and rises again in the Thermosphere (due
to the suns ability to boost temperatures). Above the Thermosphere is the Exosphere, where the atmosphere
merges into space.
Does weather happen in the other layers of the atmosphere?
The air that makes up the atmosphere is a mixture of invisible gases - mostly nitrogen (78%) and oxygen (21%) with a small amount of other gases (total of 1% -mostly argon, with a tiny amount of carbon dioxide). There is also a small amount of water vapour in the air and it is this that is the key to the weather. If we had no water vapour, there would be no weather as the troposphere is the only layer with enough water vapour to form clouds, snow or rain.
As you go up through the atmosphere, each layer has its own variation of temperature and mixture of gases. In the troposphere, the temperature reduces steadily with height - about 7ºC per km. However, up in the highest layer, the thermosphere, temperatures can be as much as 1,500ºC because the atmosphere is absorbing some of the sun's radiation.
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Oceans & Water Navigation
Quick Facts
How Weather Works
The Atmosphere <<
Day to Day Changes
The Power of the Sun
The Suns Energy
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