Global hazards

• What is the global circulation system?

  The movement of air that transfers heat from the warm Equator to the cold poles
• How do ocean currents and winds affect Earth's temperature?

  They transfer heat from the warm Equator to the cold poles
• What drives the global circulation system?

  Warm air rising causing low pressure and cool air sinking causing high pressure
• What are the three main cells in the global circulation system?

  • Polar cell
  • Hadley cell
  • Ferrel cell
• What happens at about 60° N and S in the global circulation system?

  Cold polar air mixes with warmer air and rises, creating a belt of low pressure
• What is the Inter-tropical Convergence Zone (ITCZ)?

  It is where warm air rises, creating a belt of low pressure
• What occurs in the ITCZ as air rises?

  Clouds form and release precipitation
• How does the global circulation system influence climate zones?

  • Hot and wet at the Equator
  • Hot and dry at the tropics
  • Unsettled weather around 60°N and 60°S
• What type of climate is associated with low pressure and rising air?

  Tropical climate: hot and wet
• What type of climate is associated with high pressure and sinking air?

  Dry climate: hot and dry
• What is the effect of altitude on temperature?

  Higher altitude results in lower temperatures
• What factors affect temperatures around the world?

  Insolation, albedo effect, cloud cover, surface winds, ocean currents, land and sea, and altitude
• What is insolation?

  The strength of the Sun's rays as they hit Earth
• How does the albedo effect influence temperature?

  High albedo surfaces reflect the Sun's rays, while low albedo surfaces absorb them
• How do surface winds and ocean currents affect temperature?

  They move heat around the world
• Why does land heat up faster than water?

  Water is slower to heat up but stays warm for longer
• How does altitude affect temperature?

  Air pressure is lower at higher altitudes, making temperatures colder
• What is the hottest place on Earth?

  The Lut desert in Iran
• Why is the Lut desert so hot?

  It is on the Tropic of Cancer with intense insolation and low albedo
• What is the coldest place on Earth?

  Antarctica
• Why is Antarctica so cold?

  Sun's rays are less intense and ice reflects these rays
• What is wind?

  Wind is the movement of air from high pressure to low pressure
• What affects the strength of the wind?

  The greater the difference in pressure, the stronger the wind
• What are the types of winds that affect weather?

  • Trade winds
  • Katabatic winds
  • Jet streams
  • Tornadoes
  • Tropical storms
• What are trade winds?

  Winds that blow from high pressure belts to low pressure belts
• What are katabatic winds?

  Air flowing downhill, such as in Antarctica
• What are jet streams?

  Strong winds in the atmosphere that can affect mountain tops
• What are tornadoes?

  Very strong rotating winds
• Why are the strongest winds in the UK usually recorded on mountain tops?

  There is less friction when winds pass over the sea
• What affects precipitation around the world?

  • Global circulation system
  • Frontal rainfall where warm and cool air meet
  • Convectional rainfall from intense insolation
  • Relief rainfall from warm air forced to rise over mountains
• Why are some areas wet and others dry?

  Due to factors like relief rainfall and the rain shadow effect
• What is the driest cold desert?

  Antarctica
• Why is Antarctica so dry?

  The air is so cold that it can hold very little water vapor
• What is relief rainfall?

  • Occurs when moist warm air is forced to rise over mountains
  • Results in precipitation on the windward side
  • Creates dry conditions on the leeward side
• How does the global circulation system affect precipitation levels?

  Areas with low pressure have rising air and high levels of precipitation
• What is the effect of intense insolation on air?

  It causes the air to become warm and rise, leading to convectional rainfall
• Where do tropical storms typically form?

  Over tropical oceans
• What is the wind speed threshold for tropical storms?

  Over 120 km/h
• What weather phenomenon is associated with droughts?

  Periods of much less precipitation than usual
• What atmospheric condition is linked to drought?

  Long periods of high pressure