Passage 3
1) Atmospheric circulation is the movement of air across the planet, and this occurs
in a pattern. The Equator is the hottest part of the Earth. When air rises at the
Equator, this leads to low pressure and rainfall. When the air reaches the edge of the
atmosphere, it is unable to go any further and so it travels to the north and south.
The air becomes cold and then falls, creating high pressure and dry conditions at
around 30º north and south of the Equator. Large cells of air are created in this way.
Air rises again at around 60º north and south and descends again around 90° north
and south.
(2) Global atmospheric circulation creates winds across the planet and leads to areas
of high rainfall, like tropical rainforests, and areas of dry air, like deserts. Another
example is a tropical cyclone which is a very powerful low-pressure weather system
which results in strong winds (over 120 km/h) and heavy rainfall (up to 250 mum is
one day). Tropical cyclones have different names depending on where they occur in
the world. In the US and the Caribbean, they are known as hurricanes, in South Asia
cyclones, in East Asia-typhoons.
1) Atmospheric circulation is the movement of air across the planet, and this occurs
in a pattern. The Equator is the hottest part of the Earth. When air rises at the
Equator, this leads to low pressure and rainfall. When the air reaches the edge of the
atmosphere, it is unable to go any further and so it travels to the north and south.
The air becomes cold and then falls, creating high pressure and dry conditions at
around 30º north and south of the Equator. Large cells of air are created in this way.
Air rises again at around 60º north and south and descends again around 90° north
and south.
(2) Global atmospheric circulation creates winds across the planet and leads to areas
of high rainfall, like tropical rainforests, and areas of dry air, like deserts. Another
example is a tropical cyclone which is a very powerful low-pressure weather system
which results in strong winds (over 120 km/h) and heavy rainfall (up to 250 mum is
one day). Tropical cyclones have different names depending on where they occur in
the world. In the US and the Caribbean, they are known as hurricanes, in South Asia
cyclones, in East Asia-typhoons.
