18
The world around us
What do plants
and animals
breathe?
1
Say the names of:
a)
The layer which has air.
b)
The layer which has almost no gases.
R E A D & T H I N K
The air around us
1.
We live in the
troposphere
which has the air we breathe. Air is made up of oxygen, nitrogen and small
amounts of other gases, such as carbon dioxide. It’s where weather occurs – there are
clouds
in this layer.
It’s the
sky
that we can see. The troposphere surrounds us on Earth and rises to about 17 km above the
Earth’s surface.
2.
The
stratosphere
is the next layer above the troposphere. It rises to about 50 kms above sea level.
It’s where
jet planes
fly. It has less air and contains the
ozone layer
. Ozone is a gas which stops the
harmful UV-B rays of the Sun reaching us. There’s not much ozone in the troposphere because it can be
poisonous to us, but we need it to protect us.
3.
The next layer up is the
ionosphere
. It’s next to space and there are satellites here. No living beings can
live here because it has very little air.
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