GAC

• What does the global atmospheric circulation model describe?

  A worldwide system of winds moving heat
• How does wind formation occur?

  Air moves from high pressure to lower pressure
• What causes the pressure difference that generates wind?

  Uneven heating of the Earth's surface
• Why is insolation greater at the equator than at the poles?

  Due to Earth's curvature and tilt angle
• What is the process of convection in the atmosphere?

  • Hot air rises
  • Cooler air sinks
  • Creates circulation patterns
• What does the irregular heating of the Earth's surface create?

  Various pressure cells generating different weather
• What are the three cells in the three-cell atmospheric wind model?

  • Hadley cell
  • Ferrel cell
  • Polar cell
• What is the primary function of the Hadley cell?

  Circulates air from the equator to subtropics
• Where does the Hadley cell extend from?

  From the equator to 30°-40° latitude
• What are trade winds and where do they blow?

  Winds from tropical regions to the equator
• What happens when trade winds meet near the equator?

  Hot air rises and forms thunderstorms
• What climate is associated with descending air from thunderstorms?

  Warm and dry climate, often deserts
• What characterizes the Ferrel cell?

  It moves in the opposite direction of other cells
• Where does the Ferrel cell occur?

  From the edge of the Hadley cell to 60°-70° latitude
• What type of weather does the Ferrel cell account for?

  Frequent unsettled weather, especially in the UK
• What is the Polar cell known for?

  It is the smallest and weakest atmospheric cell
• What does the cold air in the Polar cell create?

  High pressure over the highest latitudes
• How does the Coriolis effect influence wind direction?

  It curves winds due to Earth's rotation
• How do winds curve in the northern hemisphere?

  Winds curve to the right
• How do winds curve in the southern hemisphere?

  Winds curve to the left
• What happens to winds in a low-pressure system?

  Winds flow in reverse direction
• What are the global wind belts produced by the atmospheric circulation?

  • Trade winds
  • Westerlies
  • Polar easterlies
• Where do trade winds blow from and to?

  From subtropical high-pressure belts to the equator
• What do westerlies blow from and to?

  From sub-tropical high-pressure belts to mid-latitudes
• Where do polar easterlies meet westerlies?

  At 60 degrees south latitude
• How does global atmospheric circulation affect climate?

  It causes certain weather types to be frequent
• What type of weather does the UK frequently experience?

  Wet and windy weather from the Atlantic
• Explain the link between global air pressure and surface wind belts.

  • Sinking air causes high pressure [1] causing winds to move away/diverge [1] to meet in areas of low pressure [1] e.g. the Polar highs/easterlies meet the westerlies (low pressure) at 60 degrees N and S of the Equator [1] 
  • Winds blow from high pressure areas to low pressure areas [1]  such as the trade winds blowing from 30 degrees N and S towards the Equator [1]