1. Extreme Weather: Hurricanes

2. Hurricanes Aims: To be able to describe where Hurricanes and Tropical Storms form and explain why they form in these locations. Explain what they need to occur and makes them more likely. Revise the Impacts and Responses to Hurricane Katrina Suggest reasons why HICs cope better with weather Hazards than LICs Use this presentation to add to your revision work! Follow the hyperlinks. Add to your notes.

3. What is Hurricane? What is a Tropical Storm or Cyclone?

4. Hurricanes are Tropical Storms What are Tropical Storms? Tropical Storms are areas of extreme low pressure. This means air is rising, causing 'low pressure' on the earth's surface. This generates High Winds. The maximum sustained surface wind speed ranges from 34 knots (39 mph or 63 kph) to 63 knots (73 mph or 118 kph).

5. Where do Tropical Storms form?

6. Whirly-Whirly Tropical storms have different names according to where they form. Each one is then given it’s own name so it can be tracked by meteorologists to forecast where they will travel and warn people of the hazards they could cause. The strongest tropical storms are called hurricanes, typhoons or tropical cyclones. The different names all mean the same thing, but are used in different parts of the world. If these huge storms start in the Atlantic, off the west coast of Africa, they are called hurricanes.

7. Where do Tropical Storms form? Tropical storms form between approximately 5° and 30° latitude North or South of the equator.

8. How Tropical Storms like Hurricanes form?

9. Print and use this sheet to create a Hurricane Formation Revision aid

10. Why do Hurricanes form here? Fill in the story board whilst watching the Hurricane animation. Click link above for animation

11. Did you get them all? Update your sheet Add illustrations to help describe each point!

12. What conditions are needed for hurricanes to form? Tropical Storms start within 8º and 15º north and south of the equator where surface sea temperatures reach 27ºC. The air above the warm sea is heated and rises. This causes low pressure. Sea depths of at least 50 metres

13. How do hurricanes form? What do they need? How do tropical storms form? Hurricanes need a lot of heat to form, which is why they usually occur over tropical seas (at least 26°C). Tropical storms usually form between approximately 5° and 30° latitude and move westward due to easterly winds The sun is close to the equator, providing energy to heat the ocean. The warm ocean heats the air above it causing it to rise rapidly. Water evaporates quickly from the hot surface of the ocean, so the rising air contains great amounts of water vapour. The rising air starts to spin (clockwise in the northern hemisphere). The Coriolis force sends them spinning towards the poles. The centre of the storm - the eye - is calm. As the air rises it cools, condenses and forms towering cumulonimbus clouds. The rapidly rising air creates an area of intense low pressure. The low pressure sucks in air, causing very strong winds. Once the storm moves over land it starts to lose energy and fades.

14. Warm water heats the air causing it to rise really quickly, then it gets pushed aside as it cools. This pushing causes the clouds to spin. When does it become a hurricane? Hurricanes are tropical storms where the winds get faster than 118 km/h (73 mph). The storms have a central area of calm known as the "eye", which is the funnel through which the warm air rises. Overland, the storms no longer have warm water to power them and die out within a few days, but not before winds do a lot of damage.

15. What causes Tropical Storms like Hurricanes to spin?

16. Watch this clip from the BBC’s Orbit: Earth's Extraordinary Journey. It helps to explain how hurricanes form and are made to spin by the Coriolis effect… The rotation (spin) of the earth “bends” the winds to the right in the Northern hemisphere and left in Southern hemisphere. This causes tropical storms to spin. Q. Why do Tropical Storms like hurricanes Spin? A. The Coriolis Effect!

17. What are Hurricanes typhoons and tropical cyclones? For this activity you will watch a video clip, make notes from the clip. Click link above for the video clip

18. Case Study: Hurricane Katrina Hurricane Katrina was a devastating storm that hit the area around New Orleans, USA, on 25 August 2005. It had social, economic and environmental impacts. New Orleans is in the United States of America. The USA is a Most Economically Developed Country.

19. Katrina 25 August 2005 Katrina was a category 4 storm. Storm surges reached over 6 metres in height. New Orleans was one of the worst affected areas because it is below sea level and protected by levees. These protect it from the Mississippi River and Lake Ponchartrain. The levee defences were unable to cope with the strength of Katrina, and water flooded into the city. Despite an evacuation order, many of the poorest people remained in the city. People sought refuge in the Superdome stadium. Conditions were unhygienic and there was a shortage of food and water. 1 million people were made homeless. and about 1,200 people drowned in the floods. Oil facilities were damaged and as a result petrol prices rose in the UK and USA. Looting was commonplace throughout the city. Tension was high and many felt vulnerable and unsafe.

20. Social impacts of the hurricane (effects on people) 1,800 people died. 300,000 homes were destroyed. 3 million people were left with no electricity. People had to move out of the area. Economic impacts of the hurricane (effects on money and jobs) $300 billion of damage. Oil platforms were destroyed. Shops were looted. Fuel prices rose. Tourism decreased. Environmental impacts of the hurricane The storm surge flooded large areas of the coast. 80% of New Orleans flooded as man-made levees (Embankments used as flood defences). overwhelmed by extra water, broke. Cotton and sugar cane crops were destroyed. Delicate coastal habitats were destroyed. Tornadoes were created. What Impacts did Hurricane Katrina have?

21. Make sure you can explain the causes and describe social, economic and environmental effects.

22. Responses to the Disaster There was much criticism of the authorities for their handling of the disaster. Although many people were evacuated, it was a slow process and the poorest and most vulnerable were left behind. $50 billion in aid was given by the US government. The UK government sent food aid during the early stages of the recovery process. The soldiers from the US National Guard were mobilised to restore and maintain law and order in what became a hostile and unsafe living environment.

23. Hurricane Katrina Day by Day Watch this national Geographic video clip telling the story of Hurricane Katrina. Add to your Day by day account of the event.

24. DayWednesday 24 th August Thursday 25 th August Friday 26 th August Saturday 27 th August Sunday 28 th August Monday 29 th August Tuesday 30 th August Wednesday 31 st August Thursday 1 st September Friday 2 nd September Aftermath What is hurricane Katrina doing? Effects and problems? Response? What are people doing?

25. Why can more developed countries (MEDCs and HICs) cope better with Weather Hazards like tropical storms better than less developed countries (LEDCs and LICs)?

26. Preparation and prediction Preparation and prediction techniques to help cope with hurricanes can be very different in MEDCs and LEDCs. Why can more developed countries (MEDCs and HICs) cope better with Weather Hazards like tropical storms better than less developed countries (LEDCs and LICs)? MEDCs have the resources and technology, such as satellites and specially equipped aircraft, to predict and monitor the occurrence of storms. They are also equipped to train the emergency services appropriately and to educate people about necessary precautions. Storm warnings can be issued to enable the population to evacuate or prepare themselves for the storm. People can prepare by storing food and water or boarding up their windows. LEDCs are often less prepared. They may not be able to afford forecasting and prediction technology to warn people of the hazard. They may not be able to afford or to make preparations for a weather hazard by storing food or clean water. They may not be able to afford adequate emergency services to cope with a disaster.They may rely on aid (sometimes reluctantly) from MEDCs for the rescue and recovery process, as was the case with Cyclone Sidr in Bangladesh, November 2007.

27. Glossary Coriolis Effect- An apparent force, due to the spinning of the Earth, which deflects movement of particles and wind. It causes tropical storms to spin. Evacuation -When people are moved from an area, often temporarily and for their safety. Habitat- Place where plants, animals and microorganisms live. Levee- Ridges or banks formed by deposits of alluvium left behind by the periodic flooding of rivers. Can also be artificially constructed banks or walls. Storm Surge – When sea level rises above the normal tidal range.