Air Pressure?

Air pressureThe force of the overlying air moleculesAltitude affects air pressureHumidity affects air pressure – dry or humid? Which molecules are lighterTemperature affects air pressuremeasured in inches of Mercury or milibars

Warm up

• What’s the barometric pressure?

Isobar

• Line of equal pressures• Look like contour lines (topographic maps)• Drawn on multiples of 4 milibars

Warm up

• Why is the weather cold and dry?• Do toilets flush differently in the Southern

Hemisphere?• Why or why not?

wind

• Named by the direction that the wind comes from

• Westerly wind comes from the west• Always go from high to low pressure – air

rushes out of a balloon

Local Breezes

• Land – heats up faster, cools faster• Water• Named by where they are coming from

Example Sea Breeze comes off the water

• Compare and contrast sea breeze vs land breeze

• Horse latitudes vs doldrums• Monsoons• ITCZ – why does it shift with the seasons.• Prevailing wind direction in United States

Test format• Multiple choice – 10• Interpret a map – label pressures at

specific points, show the general wind direction

• Draw the isobars. Label relative pressures. Draw wind direction (as practiced today.)

• Label prevailing winds. Show general pressures.

• Choose 4

Try this!

• http://daphne.palomar.edu/jthorngren/winds.htm

• It’s a wind quiz!!