Weather Hazards

• Convergence zone

  Area where air moves towards each other
• Divergence zone


  Area where air moves away from each other
• Convection Rainfall


  Air rising and cooling to form clouds and therefore rain
• Hadley cell


  Air rising at the equator, travelling to higher latitudes and sinking as cool air is heavier
• The sun's rays are more concentrated near the equator


  It receives more energy and is hotter
• This is why it rains so much in the tropics
• As air travels to higher latitudes


  It starts to cool
• As the air sinks

  The moisture in it is dropped, forming deserts
• Low pressure belts


  Areas where the air is rising
• High pressure belts


  Areas where the air is sinking
• Atmospheric circulation cells


  • 0°-30°S/N Hadley cell
  • 30°S/N-60°S/N Ferrel cell
  • 60°S/N-90°S/N Polar cell
• Features of a tropical storm

  • Eye - calm weather, no rain
  • Eyewall - strong winds
  • Rainbands - rain
  • Tornadoes
• After 14 MPH it becomes a hurricane
• Causes of tropical storms

  • Warm oceans (over 27°C)
  • Coriolis effect
  • Low air pressure - warm air rises
• Climate change will increase the intensity and frequency of tropical storms
• Tropical storms may occur more north and south of the equator as oceans become warmer
• Distribution of tropical storms

  Between 6 and 90 degrees north and south of the equator, usually between the Tropic of Cancer and Capricorn where oceans are calmest
• Reducing the effects of tropical storms

  1. Monitoring - satellite imagery, data collection

  2. Protection - shutters, storm drains, shelters, stronger buildings

  3. Planning - awareness, evacuation, hazard maps
• Weather hazards in the UK

  • Drought in summer
  • Snow
  • Flooding
  • Storms
  • Heavy rainfall
  • Heatwaves
• Formation of a Tropical Revolving Storm

  Sea surface reaches 27°C, warm air rises, Coriolis effect causes spinning, low pressure area forms, cool air sinks into eye, storm weakens when it meets land
• Typhoon Haiyan


  2013 in the Philippines, classified as a Category 5 tropical storm
• Primary effects of Typhoon Haiyan

  • 50% of houses destroyed
  • 4.1 million homeless
  • 6,190 dead
  • 75% of farmers and fishermen lost income
  • Damage to rice crops costing $53m
  • 800,000 litre oil spill
• Secondary effects of Typhoon Haiyan

  • Flooding and landslides
  • Infection and disease spread
  • Looting and violence
  • Power supplies cut off for a month
  • Schools destroyed
• Immediate responses to Typhoon Haiyan

  1. Government warning to evacuate

  2. Over 100 evacuation centres set up

  3. 800,000 people evacuated

  4. Curfew imposed to reduce looting

  5. Emergency aid arrived 3 days later
• Long-term responses to Typhoon Haiyan

  1. Cash for work programme to clear debris

  2. More cyclone shelters built

  3. Mangroves replanted

  4. No build zone established

  5. Build back better recovery plan launched in 2014
• Total damage cost of Typhoon Haiyan was $12.6 billion
• Cause of UK storms was low pressure systems moving across the Atlantic picked up by the polar jet stream
• Social effects of UK storms

  • Over 600 homes flooded
  • 16 farms evacuated
  • Temporary accommodation needed for months
  • Communities cut off
• Economic effects of UK storms

  • Over 14,000 hectares of agricultural land flooded for weeks
  • Railway lines closed, roads cut off
  • £10 million damage cost
• Environmental effects of UK storms

  • Rivers contaminated with sewage, oils and chemicals
  • Debris deposited across the land