Under Pressure!!Under Pressure!!

Feeling Pressure?Feeling Pressure?

•Air pressure is the force exerted on you by the weight of tiny particles of air.

How much pressure are you under?

•There is about 2000 lbs. of air pushing on you right now!! You are under a ton of pressure

When it's compressed, air is said to be "under high pressure".

Weather forecasters measure air pressure using a barometer. There are 2 types of barometers…

Aneroid Barometer

Mercury Barometer

1. Sun creates wind

2. Warm Air Rises

3. Cold Air Sinks

4. Wind is caused by differences in air pressure.

How do we measure wind?How do we measure wind?

Wind is measured by an anemometer (wind speed) and a wind vane (wind direction).

Anemometer Wind Vane

Coriolis effect over Earth's surface

Jet Stream-Fast-moving, high altitude winds. Moving from west to east across the United States.

Capped Bottle eventually collapsed. WHY?????- Air inside that bottle cooled off- Cooling takes place because the atoms

inside the bottle loose energy as they collide with the bottle side that is exposed to the cooler surrounding air.

But why did it collapse…

- As atoms loose energy…their velocity decreases resulting in a decrease of pressure in the bottle.

- Since the pressure inside the bottle is less than outside…the bottle is crushed.

The uncapped bottle remains unchanged. WHY?? As air cools inside the bottle, outside air moves into the bottle to equalize the pressure on both sides.

Crunch Time ExperimentCrunch Time Experiment