Atmospheric pressure Flashcards
explain atmospheric pressure?
The earth is surrounded by air, air is made up of gases that have mass. the air is, therefore, able to exert a force which is known as atmospheric pressure.
atmospheric pressure?
pressure is the mass of a column of air pressing down on the earth’s surface.
what is pressure measured in?
hPa (hectopascals)
How is pressure represented on a synoptic chart?
isobars
Describe the characteristics of a high pressure
Highest reading in the middle, air rotates anti-clockwise in the SH, air sinks, air diverges, little chance of rain. (anti cyclone)
Characteristics of a low pressure?
Lowest reading in the middle, air rotates clockwise in the SH, air rises, air converges, better chance of rain. (cyclone)
factors that influence surface pressure?
Temperature, humidity, altitude.
wind speed or known as?
pressure gradient force (PGF)
when will the air on the surface move from high to low?
As soon as there are pressure differencess - area of HP and LP.
what is the air called that moves from high to low along the surface?
wind
what is the force called that causes the air to move from HP to LP?
Pressure gradient force
what does it mean if there are small differences in pressure?
the PGF is small = gentle winds
what does it mean when there are large differences in pressure?
strong winds
where does the earth rotate the fastest?
at the equator
what results in Coriolis force?
the different speeds of the earth’s rotation
