Weather Hazards

• Hadley cell


  The main cell in global atmospheric circulation
• How the Hadley cell works

  Air rises at equator, moves towards poles, sinks at 30°N/S, causing high pressure and deserts
• Global atmospheric circulation affects regional weather patterns
• Tropical storms


  • Form over ocean temperatures above 27°C
  • Become tropical storms at 74mph winds
  • Measured on Saffir-Simpson scale 1-5
  • Only form 5-20° N/S of equator
  • Strongest winds in eye wall
• How tropical storms form

  1. Air is heated above warm tropical oceans

  2. Air rises under low pressure conditions

  3. Strong winds form as rising air draws in more air and moisture causing torrential rain

  4. Air spins due to the Coriolis effect (spin of the earth) around a calm eye of the storm

  5. Cold air sinks in the eye so it is clear and dry

  6. Heat is given off as it cools powering the storm

  7. On meeting land, it loses source of heat and moisture so loses power
• Tropical storms


  • They only form in ocean temperatures over 27 °C
  • A storm becomes a tropical storm once winds hit 74mph
  • Storms are recorded on the Saphir Simpson scale, 1-5
  • They are only found in latitudes of 5-20 degrees north and south of the equator
  • The strongest part of the storm is the eye wall, where winds are fastest
  • The centre of the storm is called the eye and is calm
• Global Temperatures are expected to rise as a result of climate change

  More of the world's oceans will be above 27, meaning more places will experience tropical storms
• Oceans will stay above 27 for longer


  Tropical storm seasons will last longer
• Higher sea temperatures


  Storms will be stronger
• Global Atmospheric Circulation


  The overall movement of air between the equator and poles that affects the Earth's climate
• Global Atmospheric Circulation causes areas to have some types of weather more than others
• The UK has a lot of low pressure systems from the Atlantic that bring wet and windy weather
• Extreme weather is when weather is significantly different from the usual weather pattern
• The UK experiences lots of extreme weather hazards
• Weather in the UK is becoming more extreme
• Temperatures have become more extreme in recent years
• It is raining more - more rainfall records have been broken since 2010 than in any other previous decade on record
• Major flooding occurs often
• Climate change can increase the frequency and intensity of extreme weather events
• Flooding is becoming more frequent in the UK as a warmer atmosphere can hold more moisture
• Low Rainfall - Rainfall over much of the UK was below what is normally expected during the months of June, July and August
• High Pressure - The long-lasting high pressure system tended to reduce the amount of rain that fell
• The record temperature, of over 38.1C (100.6F), was recorded in Gravesend, Kent, SE England
• Management Strategies can Reduce the Risk from Weather Hazards