UK Storms

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  • UK Storms
    • They are Temperate Storms
      • also called mid-latitude cyclones or extratropical cyclones
      • occur in temperate climates
        • found at mid-latitudes, 30-60oNorth or South of Equator
      • range from mild (rain showers and 15-30km winds) to severe(thunderstorms and 120km/h winds)
      • generally cause less damage than tropical storms.
        • typical impacts include road closures, power cuts, damage to trees
      • caused by depressions
        • form over sea in autumn when water is warm- warm surface water leads to warm, moist air which rises.
          • When this warm air meets polar front it rises rapidly above cold polar air creating an area of low pressure along with condensation and heavy rain
            • steep pressure gradient between two air masses drives strong winds, which spiral around the depression
              • steep temperature gradients in a depression affect storms strength - strong temp gradient=stronger pressure gradient =strong winds
    • CASE STUDY: THE GREAT STORM
      • 15th October 1987
      • Storm was caused by a depression with rapidly falling air pressure
        • 1. depression began over Bay of Biscay as south westerly winds carrying warm, wet air from North Atlantic met north easterly winds carrying cold air from the Pole
          • 2. depression deepened rapidly due to unusually warm sea surface temperatures in the Bay of Biscay and a steep temp. gradient between two air masses. Low atmospheric pressure in the core of depression led to development of very strong winds
            • 3. The polar front jet stream was located further south than normal so the depression formed over northern France and southern England rather than North Scotland
              • 4. On 15th October pressure in Centre of depression fell from 970mb to 953mb at midnight much lower than average of 1013mb
                • 5. The storm hit the south coast of Cornwall and Devon shortly after midnight moved across the Midlands and reached Humber Estuary on the east coast ar around 5:30am on 16th oCT
                  • 6. South East suffered especially severe winds between 3 and 6 am with gusts up to 196km/h at  Gorleston in Norfolk
                    • 7. After 6am depression began to weaken and moved away over north sea
      • Impacts
        • Social
          • 18people died in England, and 4 in France
          • Power and telephone lines were knocked down
          • 150000 Lost their telephone connection
          • Historical buildings were damaged or destroyed e.g. Shanklin Pier
          • no electricity for 24hours
        • Economic
          • Insurance claims totalled £1.4billion
          • Gatwick airport closed
          • Transport was disrupted as fallen trees blocked path
        • Environment
          • 15million trees were blown down
          • 97% loss of trees in area losing abitat of wildlife
      • Responses
        • During
          • During storm emergency authorities dealt with huge numbers of emergency calls
            • four months of phone calls on one night
        • After
          • Phone companies and electricity boards worked around the clock repairing and replacing
          • Highways agencies began clearing roads
          • Forestry workers began collecting fallen trees in forests
            • took over two years
          • Forestry Commission established Committe to help woodland owners recover fallen trees and offer advice on replanting
        • MET OFFICE
          • criticized for how they forecast the storm and issued warnings
            • severe storm warnings only issued about 3 hours before storm

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