Ch 19.2 Pressure Centers and Wind

Vocabulary:

Cyclone

• Anticyclone
• monsoon
• polar front

Label the following winds on a globe

• trade winds
• westerlies
• polar easterlies

Distinguish between a cyclone and an anticyclone

A cyclone is a low pressure system where the pressure decreases from the outer isobars toward the center.

An anticyclone is a high pressure system where the pressure increases from the outer isobars toward the center.

Explain how winds blow across pressure centers in the Northern and Southern Hemispheres

When the pressure gradient and the Coriolis effect are applied to pressure centers in the No. Hemisphere winds blow…

• counter clockwise around a low and
• clockwise around a high

In the So Hemisphere, the Coriolis effect deflects winds to the left, therefore winds blow…

• clockwise around a low
• counter clockwise around a high

Describe the air pressure patterns within cyclone and anticyclones

•  In cyclonic (low) flow, air converges or spirals inward. 
• As it does this, it must grow taller to allow for the decreased area it now occupies.
• The rising column of air diverges aloft.  If it did not, the low pressure could not be maintained as the extra air converged at the surface

Cyclones are associated with unstable, stormy weather as the low pressure center sends air aloft.

• In an anticyclone (high) air flow diverges at the surface. 
• The diverging air is “replaced” by air from above
• This causes convergence aloft

Anticyclones are associated with clear skies as air descends from aloft

Describe how friction controls the net flow of air around a cyclone or an anticyclone.

Explain how unequal heating of Earth’s surface affects temperature.

Useful Power Point

http://www.slideserve.com/elsie/prentice-hall-earth-science