Weather Hazards

• Droughts are prolonged periods of abnormally low rainfall, resulting in a shortage of water for crops, livestock, and human consumption.
• What is atmospheric weathering?

  The process of breaking down rocks and minerals on Earth's surface due to exposure to the atmosphere.
• What are examples of atmospheric hazards?

  Air pollution, smog, ozone depletion, greenhouse gases and acid rain.
• What is high pressure?

  1. Caused by cold air sinking.
  2. Causes clear and calm weather.
• What is low pressure?

  1. Caused by warm air rising.
  2. Causes cloudy, stormy weather.
• What are katabatic winds?

  Winds that carry air from the high ground down a slope due to gravity.
• What are trade winds?

  Winds that blow from high pressure belts to low pressure belts.
• What are jet streams?

  These are winds that are high in the atmosphere travelling at speeds of 225km/h
• Examples of extreme weather include:

  1. Wellington, New Zealand: winds reached up to 248km/h (154mph).
  2. The Atacama, Chile: the Andes mountains block moist air travelling west. This leaves storms on the east of the mountains and a rain shallow to the west.
• What is precipitation?

  1. Warm air rises
  2. Condenses to form clouds
  3. As it cools further, it starts to rain
• How do tropical storms form?

  1. Warm air rises over the oceans.
  2. Once the water reaches 27C, it starts to cause low pressure.
  3. This leads to thunderstorms and more water is sucks up from the trade winds.
  4. With the trade wind blowing in the opposite direction to the spin of the earth, the storm starts to spin - picking up more water as it moves.
  5. Once the winds reach above 74mph, it is officially a tropical storm.
  6. Once it reaches land it loses energy but causes massive damage.