Extreme Weather
- 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
- D: low pressure w. system- wet conditions- descending air- clockwise
- 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
- Risks
- Hurricanes
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