• It is the weight of air pressing on a unit area.
• The difference of air pressure is due to
unequal heating of the Earth.
• Warm air masses have fewer air molecules
than cold air masses.
What is the relation between
temperature and pressure ?
As the temperature increases the air particles
are far away from each other decreasing the
As the temperature increases the pressure
• Air Pressure is a
measure of the force
of the air pressing
down on the earth’s
Air Pressure can vary at any particular
point on the Earth depending on the
density of the air
Density = mass / volume
Title: Activity 2. Stop the Leak
Date: Feb. 2010
How can you stop the leak in this soda can?
-Suppose air in an area is cool and under high pressure
-If a near by place is warmer and at a lower pressure
-The air will move from high pressure area to a low
pressure area .
This is called “Surface wind”
• What do you think can increase the intensity of the wind ?
• As the difference in pressure increases the wind intensity
• Unequal heating and cooling of air results in difference in
• Where warm air will move
• Up and cold air moves down making a circular pattern of
rising and sinking air and wind called “Convection cell”