Under pressure
Air pressure is the weight of the atmosphere pressing down on the
earth.
You may have seen the weatherman talking
about air pressure on TV during a weather
forecast. It is an important thing to know, as it
can actually determine the type of weather we
get where we live.
Air Pressure is measured by a barometer. You
can see a barometer on the left. Barometers
may also use mercury in a glass column, like
a thermometer, to measure the change in air
pressure. When the weather is calm the
mercury in the barometer stays fairly low
against the measure.
If a high pressure system is on its way, often you can expect cooler
temperatures and clear skies. If a low pressure system is coming, then
look for warmer weather, storms and rain.
Air pressure also changes with altitude. When you move to a higher
place, say a tall mountain in Scotland, air pressure actually decreases
because there are fewer air molecules as you move higher up.
earth.
You may have seen the weatherman talking
about air pressure on TV during a weather
forecast. It is an important thing to know, as it
can actually determine the type of weather we
get where we live.
Air Pressure is measured by a barometer. You
can see a barometer on the left. Barometers
may also use mercury in a glass column, like
a thermometer, to measure the change in air
pressure. When the weather is calm the
mercury in the barometer stays fairly low
against the measure.
If a high pressure system is on its way, often you can expect cooler
temperatures and clear skies. If a low pressure system is coming, then
look for warmer weather, storms and rain.
Air pressure also changes with altitude. When you move to a higher
place, say a tall mountain in Scotland, air pressure actually decreases
because there are fewer air molecules as you move higher up.
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