1. Properties of Gases
2/1/02
Revised 3/20/08

2. Gases Gases are made of molecules. Molecules have mass.
Heat increases molecular collisions causing volume to increase.
Decreasing temperature reduces volume.
View flash animation here.

5. Air Pressure
Gravity pulls gasses down causing an increase in gas density.
Increased density causes more molecular collisions.
More collisions produce more force on things the gases hit.

7. Why does hot air rise? Heat increases gas volume.
Increases volume decreases density.
More dense cooler air squeezes the hot air up.
Less dense things float on things that are more dense.

9. Convection
The transfer of heat due to movement caused by density differences in fluids like water or air.
This is what makes wind and some ocean currents.