The air you breathe forms a thin layer – the ‘atmosphere’ – around the Earth. This stretches up for a few hundred kilometres. As you go higher, there is less air. At the height where planes fly, there is too little air to breathe.

Most plants and animals need atmospheric gases in order to live. Animals rely on ‘oxygen’ to breathe and plants rely on ‘carbon dioxide’ to make their food. The air also contains nitrogen, small amounts of other gases, and some water vapour and dust. The ‘stratosphere’ and ‘ionosphere’ contain small amounts of ‘ozone’, which is a form of oxygen. A layer of ozone prevents harmful ultraviolet rays from the Sun reaching the Earth’s surface.

 

 

 

 

 

 

 

The aurora is caused by charged particles from the Sun hitting the atmosphere.

 

 

 

 

 

 

 

Exosphere

The highest, outer region of the Earth’s atmosphere is called the ‘exosphere’. Here, conditions are not very different from outer space as there is only very little air indeed.

Ionosphere

The ‘ionosphere’ is made up of electrically charged particles produced when radiation from the Sun hits the upper atmosphere. Near the poles, this causes a brilliant display of lights, the ‘aurora’.

Man-made pollution is now causing a hole to appear in the ozone layer.

Stratosphere

The ‘stratosphere’ extends up to about 80 km above Earth. As you travel upwards in this layer, the temperature rises slightly; nevertheless temperatures are below freezing point.

Troposphere

The ‘troposphere’ contains the air we breathe. Clouds rain and snow all form in this layer. As you travel up through the troposphere, it becomes colder.