15-+The+atmosphere

= Air  =

=Air is the mixture of gases that surrounds the Earth.= =The main gases in air are:= =• Nitrogen (the most abundant gas)= =• Oxygen. (Plants produce oxygen and all living things need oxygen to breathe).= =• Carbon dioxide. (Living things produce carbon dioxide when they breathe out. It is also produced by cars and factories).=

=We need air for= || =Hearing.=
 * =Breathing=

Sound travels through air.
||
 * =Flying.=

Birds, butterflies and aeroplanes cannot fly without air.
|| =Burning.=

Fire needs oxygen from the air in order to burn.[[image:images (5).jpeg width="324" height="222"]]
|| = = =The properties of air media type="youtube" key="VweKlhcMYPo" width="336" height="187" align="right"=
 * =Air is invisible.=
 * =It has no colour or smell.=
 * =It has no shape or volume of its own.=
 * =Air has weight. A balloon with air inside weighs more than a balloon with no air inside.[[image:pekewiki-loja/images (6).jpeg width="664" height="188"]]=
 * =Air occupies space. If you inflate a balloon, it changes its shape because of the air inside.=
 * =Air does not have its own shape.=

= = =The atmosphere=





= LAYERS OF THE ATMOSPHERE =



=Watch these videos to learn about our atmosphere:= media type="youtube" key="BbwEF6xvlVg" width="560" height="315" align="center"

media type="youtube" key="5sg9sCOXFIk" width="417" height="244" align="left"

media type="youtube" key="fyfN9t_E0w8" width="448" height="251" align="right"

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