Tropical storms revision


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Tropical storms revision

  1. 1. Tropical Storms Revision
  2. 2. Causes Where? Sea Surface Temperature above 27 °C Most between 10 ° and 30 ° north and south of the equator Rarely within 5 ° of equator What? Large areas of low pressure or extreme depressions On satellite images appear as huge, swirling masses of cloud An eye (calm clear area) visible in centre Measurement Strength measured on Saffir-Simpson scale Formation <ul><li>Several thunderstorms drift over warm seas </li></ul><ul><li>The warm air from the sea surface and the thunderstorms combine and warm air starts to rise </li></ul><ul><li>More warm air rises and due to the earth’s rotation starts to move in a spiral. It cools and condenses, forming clouds, releasing much energy </li></ul><ul><li>The air starts to rise faster and cooler air is sucked downwards. Wind speed starts to increase </li></ul><ul><li>The tropical storm moves over the ocean, picking up warm moist air. Wind speeds reach more than 120km/h as more cold air is drawn into the eye </li></ul>Widespread destruction strongest gusts 250+ 5 Significant structural damage, widespread power failure strongest gusts 210-249 4 Some structural damage, power failure likely strongest gusts 180-209 3 Minor house damage, heavy crop damage strongest gusts 150-79 2 Damage to some crops, trees and caravans strongest gusts 120-149 1 Effects Wind Speed (km/h) Category
  3. 3. Storm surges (abnormal rise of the sea along a shore as the result of a storm, sometimes called a tidal surge) flooding coastal area Structural damage to buildings Roads and other infrastructure, vehicles and other property destroyed Sensitive environments destroyed Loss of animal habitats Sea fish killed due to silting Freshwater fish killed in storm surges Fishing boats and other craft damaged Electricity lines blown down causing power cuts High winds tear roofs of buildings or collapse, partially due to poor construction Trees uprooted Roads and transport links become impassable, hindering emergency services Heavy rain causes extensive flooding, flushing out sewers and spreading disease People suffer trauma and stress Catch water-borne diseases People displaced and communities broken up Food and water shortages Job losses due to damage to industries Civil unrest and looting Loss of life among people, livestock and wildlife Cost of repair and insurance claims Loss of income as businesses close Crops destroyed and exports lost Oil prices may increase Social Effects Environmental effects Economical Effects
  4. 4. Reducing the Damage Forecast  Prepare  Act Forecast Development and movement of tropical storms closely monitored By agencies like the National Hurricane Center (Atlantic) and the Joint Typhoon Warning Centre (Pacific) Warnings issued to places where tropical storm is likely to strike Only 20-25% chance of knowing exactly where storm will strike, 48 hours in advance Speed and path affected by many factors, making them unpredictable Regularly updated forecasts available on internet. Forecast map includes a area or “cone” of uncertainty, where the hurricane may strike within a 3 day or 5 day period People within area should prepare for the possibility that the storm could hit them Analyse large amounts of data and use computer modelling Prepare Education programmes to increase awareness School lessons, posters and leaflets give advice on drawing up a family disaster plan, putting together an emergency kit and simple methods of preparing homes from strong winds and flying debris Buildings designed and built using materials tested on storm stimulators Windproof tiles, water-resistant windows and strengthened building structures developed, but expensive In areas at risk of storm surge, ground floor walls wash out, leaving only supports, so waves can wash through In LEDC’s NGO’s help put simple but effective measures in place Act When forecasted, evacuation plans are put into place
  5. 5. Case Studies Bangladesh <ul><li>NGO schemes are </li></ul><ul><li>Educating women on what to wear in case they have to swim during a cyclone </li></ul><ul><li>Building homes on stilts in case of storm surges </li></ul><ul><li>Building cyclone shelters </li></ul><ul><li>Training local people to organise others in an evacuation </li></ul>Texas Due to educational campaigns ,those outside of the danger area did not move out, leaving the highways clear for those in most danger. One millions people along the coast of Texas in the USA were evacuated as Hurricane Ike approached in September 2008. In parts of Galveston, much of which is on low lying islands, there was a mandatory evacuation order Over 1350 buses helped transport people to higher ground Hurricane Hanna In Haiti on the 3 rd Sept 2008 Recently had Fay on 15 Aug. 2008 and Gustav on26 Aug. 2008 Unexpected, so people were unprepared and had no warnings to evacuate 550 people died Many tin roofed houses destroyed, leaving almost 3million homeless Thousand left stranded on their rooftops Ground already saturated from other hurricanes so floodwaters rose quickly Roads and bridges washed away, so only way out of Gonaives was by air or wading High risk of disease from contaminated water In other parts, whole villages buried by fast flowing mudslides 98% of forests removed, so little natural defence from mudslides Flimsy shacks carried away and crops, goats and cows destroyed, taking away food and income UN troops supervised food aid distribution, fearing outbreaks of rioting, due to many hungry people 3 days later hurricane Ike (cat. 4) also hit, claiming another 74 lives and worsening food crisis. Last bridge standing in Gonaives washed away, and city so badly hit is was thought that it may need to be rebuild elsewhere