Extreme Weather

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  • Created by: 287035
  • Created on: 26-04-14 14:33
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  • Extreme Weather
    • Hurricanes
      • Case study: Hurricane Katrina 2005
      • 1.t.s drift over warm o. surface
      • 2. w. air rises- l. pressure at surface
      • 3. air rises faster to fill l. pressure- sucking cooler drier a. downwards
      • 4. a. spirals, cools&condenses as it rises- walls of cumulonimbus c. around centre of s.
      • 5. condensation releases heat energy- powers s.&^wind speed
      • 6. c. air sinks down through centre- eye- calm
      • 7. h. reaches l.- source of h.e. and moisture disappear
    • Depressions and anti-cyclones
      • D: low pressure w. system- wet conditions- descending air- clockwise
        • 1. Infancy- 2 air masses (T&P) meet- embryo d. formed
        • 2. Maturing- w. air undercut by c. air (more energy & less dense)
        • 3. Occlusion- decaying stage- c. front moves faster than w.f.- closes gap (occluded front)- no w. air in contact with ground
        • 4. Dissolving- frontal system dies out- only c. air remains- occ. dies as temp.=similar on both sides
      • AC: high pressure w. systems- dry conditions- rising air- anti c.- only 1 air mass- no fronts
    • What is extreme weather?
    • Droughts
      • Causes
      • Types
        • Agricultural- prolonged shortage of soil moisture
        • Hydrolorical- water reserves fall below average levels
        • Meteorological- prolonged period of less than average rainfall
    • Floods
      • Risks
        • Deforestation- reduces interception by veg.
        • Ploughing- overgrazing- less vegetation- ^run off
        • Urbanisation- highly impermeable surfaces & building on floodplains
        • Rainfall- intense r. reduces infiltration c.-prolonged- saturated soil
      • Management
        • Dams- multi-purpose- water for locals- cause great flooding if broken- expensive
        • Flood walls-easily and quickly constructed- water through joints if not assembled well
        • Washlands- enriches soil, cost effective- productive land into marshland
        • Afforestation- soil erosion prevented- conifer trees= acidic soil


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