Phys GeoG, Test 2 pt 1

atmospheric pressure

weight of the atmosphere described as force per unit area

Increasing altitude =

decrease in air pressure and air density

What is the weather when pressure is increasing?

dry and cold weather

What is the weather when pressure is decreasing?

rainy and warm weather

how is air pressure measured?

using a barometer

Wind

the mostly horizontal motion of air across the earth’s surface; caused by differences in atmospheric pressure; air moves from areas of higher atmospheric pressure to areas of lower pressure

If pressure gradient is high =

winds are strong

If pressure gradient is low =

winds are weak

4 driving forces that control atmospheric motion

1. gravity

2. pressure gradient

3. coriolis force

4. surface friction

coriolis force

product of the fact that the earth is spinning; as earth is spinning, rates of motion change depending on latitude position

surface friction

negative force; dragging air; result of rough surface of the earth creating friction as atmosphere runs through rough surface; layers of atmospheres moving different directions or speeds; reason why airplane takeoff/landing is so rough and bumpy

high pressure

wind flowing down and spreading in all directions (cold)

low pressure

wind flowing up into atmosphere against gravity; air flowing towards the low (hot)

driving force of global atmospheric circulation

latitudinal distribution of solar insolation; the equatorial regions are hot, the poles are cold

hot air

less dense and rises creating lower atmospheric pressure at the surface

cold air

more dense and falls creating higher atmospheric pressure at the surface

geostrophic

a movement of air or water that flows parallel to pressure lines because two major forces, the push from air/water pressure and the turning push from the Earth's rotation, cancel each other out

deflection

to cause something to change direction or to turn aside from a path or focus