FridayApril 22, 2011

(Wind)

The Launch PadFriday, 4/22/11

According to this map, what was

the average temperature in the following

cities from Feb 25 – Mar 3,

2001?

DFWGalveston, Tx

Miami, FlChicago, Il

St. Paul, Mn

50o 60s 70s 30s 10s

Announcements

Please check your yearly average in this class.

If you are below 70 for the year, please come and see

me ASAP!There are only two more

grades remaining!

Assignments For This Six-Weeks Date Issued Date DueLab – Air Masses, the Mid-Latitude

Cyclones, and Weather Maps 4/20 4/25

Wind“Wind” is defined as the horizontal movement of air.

Air moves out of areas of higher pressure into areas of lower pressure.Unequal heating of Earth’s surface generates these pressure differences.Solar radiation, therefore, is the ultimate energy source for most wind.

Wind is controlled by a combination of forces, including:the pressure-gradient force

the Coriolis effectfriction

Isobars are lines that connect places of equal air pressure.The spacing of isobars indicates the amount of pressure change over a given distance

and is expressed as the “pressure gradient.”

WindThe Coriolis effect is also a participant in controlling the wind.

This effect is an apparent deflection in the wind direction

due to the Earth’s rotation.

Deflection of the wind is to the right in

the Northern Hemisphere and to

the left in the Southern

Hemisphere.

Wind

Finally, friction acts to slow the air’s movement near

the surface.

WindUpper level winds generally blow parallel to isobars, and are called geostrophic winds.The Jet Stream is a “river” of air at high altitude with a velocity of 120–240 kilometers per hour.

The Geostrophic Wind

Figure 18.8

Comparison of Upper-

Level Winds and Surface

Winds

Continue LabAir Masses, the Middle-Latitude

Cyclone, and Weather Maps