1. Air Pressure
Air pressure determined by how much the air weighs in a given space.
It varies with altitude.
Denser air in lower altitudes
Lighter air in higher altitudes
It is also a function of temperature and density.
Pressure is important factor is weather.

2. Air Pressure
As air descends, it warms, preventing cloud formation  good weather.
This is a high pressure system that circulates clockwise.

3. Air Pressure
As air rises, the pressure at the surface is low, it cools and condenses to from clouds precipitation  bad weather
This is a low pressure system that rotates counter-clockwise.

4. Air Pressure & Wind Measurement
Barometer: an instrument that measures pressure
Anemometer: an instrument that measures wind speed

5. Weather Maps Isobars: connected lines of constant pressure
H: High Pressure
L: Low Pressure
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6. Weather Maps What is the temperature? What is the pressure?
What is the wind direction?