Air Pressure

• what is the definition of air pressure?

  the weight of air pressing down on the surface
• what is air pressure measureed in?

  millibars (mb)
• what are the units for air pressure?

  mb
• what is the definition of atmospheric pressure?

  the force exerted by the atmosphere on the earth's surface
• what happens to warm air?

  Warm air is less dense so it rises. This will lead to low pressure
• what does warm air lead to?

  low pressure
• what does cool air lead to?

  high pressure
• what happens to cool air?

  Cool air is less dense so it sinks. This will lead to high pressure
• what is the definition of water vapour?

  = water as a gas. invisible
• what is the definition of water droplets?

  they are drops of water (liquid)
• what is the definition of condensation?


  when water vapour (gas) cools and becomes water droplets (Liquid)
• what is the definition of evaporation?

  when water droppplets (Liquid) turns to water vapour (gas)

  • a change of state
• what is the definition of humidity?

  the vol of water vapour in the air
• what is the definition of relative humidity?

  the volume of water vapour in a given air mass in relation to the volume that the air mass is capable of holding
• what is relative humidity expressed as?


  a %
• Give details about low pressure?

  warm air rising

  winds

  warm air rises, cools , condenses

  condenses -> clouds

  precipitation
• give details about high pressure?

  Cool air sinking

  clear skies

  calm

  little or no winds

  heatwaves/ frosts