Chapter 19Atmospheric Pressure

• Air Pressure

• High Pressure

• Low Pressure

• The weight of the atmosphere

• Good weather

• Bad weather

• Barometer • Instrument used to measure atmospheric pressure

• Either in mmHg or in millibars

• Dry Air……..

• Humid Air……….

• Heavy

• Lighter because the water molecules push the nitrogen and oxygen apart

• Isobar • Lines that connect points of equal PRESSURE

• Low pressure area

• High pressure area

• Air moves counterclockwise and in toward the low

• Air moves clockwise and out away from the High pressure area

• WIND!!!!! • The movement of air from an area of high to low pressure

• Coriolis Effect • Because the earth rotates to the East, winds on earth get deflected or turned to the west

Jet Stream

Land & Sea Breezes

• Warm breeze at night and a cool breeze during the day due to …..

• …the unequal heating of land and water

• Anemometer

• Wind Vane

• Measures wind speed

• Measures the DIRECTION of the wind

Chapter 21

• Climate is the long-term weather of an area• Weather changes day to day; climate

changes once every couple of centuries.• Virginia’s Climate is MILD.