The atmosphere is a mixture of nitrogen (78%), oxygen (21%), and other gases (1%) that surrounds Earth. High above the planet, the atmosphere becomes thinner until it gradually reaches space. The atmosphere is an important part of what makes Earth livable. It blocks some of the Sun’s dangerous rays from reaching Earth. It traps heat, making Earth a comfortable temperature. And the oxygen within our atmosphere is essential for life.
Layers of the Earth’s Atmosphere
- The troposphere is the first layer above the surface and contains half of the Earth’s atmosphere. Weather occurs in this layer.
- Many jet aircraft fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.
- Meteors or rock fragments burn up in the mesosphere.
- The thermosphere is a layer with auroras. It is also where the space shuttle orbits.
- The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.
One of the most important benefits the atmosphere provides is maintaining the Earth’s temperature. On the moon, which has no protective atmosphere, temperatures can range from 121 degrees Celsius in the sun (250 degrees Fahrenheit) to negative 157 degrees Celsius in the shade (negative 250 degrees Fahrenheit). The atmosphere serves as a protective shield against radiation and cosmic rays. The atmosphere also serves an important purpose as a medium for the movement of water. Vapour evaporates out of oceans, condenses as it cools and falls as rain, providing life-giving moisture to otherwise dry areas of the continents.