Air pressure

Air pressure

• 1.
  Air Pressure  Thepressure exerted on an object by the air. – Occurs in all directions  up, down, sideways
• 2.
  Air Pressure  Abarometer is used to measure the amount of pressure in the air. – Units = mmHg (millimeters of Mercury) or atm (atmospheres)
• 3.
  Barometers  Rapidly fallingpressure almost always means an approaching storm system.  Rapidly rising pressure almost always means clearing and cooler weather is ahead.
• 4.
  Winds  Winds arecreated by horizontal air pressure differences – pressure gradients  Uneven heating of the Earth creates pressure differences
• 5.
  What affects wind? Pressure differences- Cause air to move  The Coriolis Effect- causes global winds to be deflected  Friction- slows down air, which changes wind direction
• 6.
  Measuring Pressure  Isobars-lines of equal pressure – Much like contour lines, but instead of elevation, they are lines of equal pressure – Are used to predict where weather is moving
• 7.
  Jet Stream  Fast flowing, relatively narrow air currents found just under the tropopause  Form at the boundaries of adjacent global wind belts
• 8.
  Global Winds  Globalwinds are created by the unequal heating of Earth.  The equator is much hotter than the rest of Earth, causing an extremely low pressure.
• 9.
  Global Winds  Thiscauses air from adjacent areas to move towards the equator.  This movement begins a chain reaction of air movement throughout Earth, creating 6 wind belts.
• 10.
  High Pressure Zone/Cyclone  Occurs when temperatures are cold  Little or no moisture (humidity) – The air is heavy and sinks towards Earth’s surface  Winds move outward and clockwise around the center of a cyclone
• 11.
  Low Pressure Zone/Anticyclone Occurs when temperatures are warm  Can have large amounts of moisture (humidity) – The air is light and rises upward into the atmosphere  Winds move outward and counterclockwise around the center of the anticyclone
• 12.
  The Coriolis Effect The Coriolis effect is a result of the spinning of Earth.  As Earth spins, anything moving in a straight line from North to South will be deflected sideways. – In the Northern Hemisphere, winds, water, and other fluids will be deflected to the right at a 90o angle. – In the Southern Hemisphere, everything will be deflected to the left at a 90o angle.
• 13.
  Assignment  Complete procedurequestions for “Air Pressure Demonstration”  Identify Types of Energy Transfers Worksheet