In weather, what does high pressure and low pressure mean?
You make a high pressure when you squash lots of air into a small space.
Imagine you were pumping up a bicycle tire. You can pump a lot of air into
a tire - more air than would normally fit into a space the size of a
bicycle tire. The air inside the bicycle tire is at a high pressure.
When they talk about high and low pressure in the weather they mean that
sometimes the air above a n area of land can get slightly more squashed up
than is normal. This is a high air pressure. The reverse can also happen -
the air can be slightly more spread out than normal and this is called a
low air pressure.
When there is a high pressure in the air above a piece of land there is
nothing to stop it spreading out into the air that is at a low pressure.
When you get a high pressure bit of air next to a low pressure bit of air
the air will move from the high pressure to the low pressure. This movement
of air is wind.
Thanks for the question.
Click here to return to the Environmental and Earth Science Archives
Update: June 2012