air pressure

• air pressure is the weight of air pressing down on the earths surface
• air pressure is measured in millibars, using a barometer
• the movement of the pointer on a barometer shows how the air pressure is changing and tells us what weather to expect:

  • rising barometer: weather improving due to high pressure
  • falling barometer: weather is declining due to low pressure
• high air pressure = air is sinking
• low air pressure= air is rising