Air Pressure

What is Air Pressure?

• The weight of the air pushing down on us and everything else around us.

• Happens because of the gravitational pull.

Air Pressure

• Air pushes on you with a force of 14.7 pounds per square inch. The force on 1,000 square centimeters (a little larger than a square foot) is about a ton!

Why doesn't all that pressure squash me? • Remember that you have air inside your

body too, that air balances out the pressure outside so you stay nice and firm and not squishy.

ELEVATION

Higher elevation = lower pressure

Lower elevation = higher pressure

HIGH & LOW PRESSURE SYSTEMS

HIGH PRESSURE

• Cold• Dry• Sinking air• Clockwise

rotation

LOW PRESSURE

• Warm• Moist• Rising air• Counterclockwi

se rotation

Cold, dry air = higher pressure (heavier) Molecules spread out;

Fewer molecules in a certain space

Molecules crowd together;More molecules in

a certain space

Compare Warm Air and Cold AirWarm, moist air = lower pressure (lighter)

How does air pressure relate to weather?

• Helps to determine if there will be rain or sunny skies; cold or hot air; etc…

Low Pressure systems

• Warm • Humid• Rainy• Cloudy weather• Thunderstorms• Severe weather• The warm air rises, condenses, forms clouds

and rains!

Low Pressure Weather Results

High Pressure systems

• Sunny skies• Cooler temperature• Dry air• Beautiful weather

High Pressure Weather Results

Front Animations

• Cold Front• Warm Front• Stationary Front• Occluded Front

Your Turn!!!

• Now YOU are going to demonstrate air pressure by doing a Metal Can Experiment!!