1. Learning objective: To be able to describe the distribution of hazards

2. Map from memory In groups of 4
Number yourselves between 1 and 4
When your number is called you may come and see the image
Recreate the image on your own map
Consider what information is important to your diagram.

4. Use p 71
Sketch on your map the distribution of tropical storms.

5. What are the characteristics of tropical storms?

8. Describing distribution
Can you see patterns or do they occur randomly?
Do they occur on land or in the sea?
Which continents can you identify?
Are they north or south of the equator?
What is the latitude? – degrees north and south of the equator e.g. the tropic of cancer is 23o north

9. Distribution of tropical storms

10. Use your skills to analyse this photograph
Lesson objectives: To describe the characteristics and causes of tropical storms
Use your skills to analyse this photograph

11. Characteristics? – what do we already know?
What are typhoons like?

12. Location
Tropical storms are normally found between the tropics near the Equator.
The formation of tropical storms is not fully known, but scientists do know that they draw their energy from warm seas.

13. High winds
High Winds : In severe tropical storms the maximum sustained winds can approach 200 km/h with short period gusts closer to 300 km/h.
Such violent winds can devastate natural vegetation and all but the strongest man-made structures.

14. Flooding
Heavy rainfall is associated with tropical storms. Heavy rainfall actually causes much more damage and deaths than high winds.

15. Landslides
Landslides are a secondary hazard. Landslides can be triggered when large amounts of rainfall saturate the ground increasing the stress on the slope.

16. Storm surges
 Tropical storms moving in land can create storm surges and big waves. If tropical storms coincide with spring tides the impacts can be severe

17. Measuring tropical storms
Saffir Simpson Scale
Storms below 74mph (119kph) are described as only tropical storms. Anything above this speed is officially a hurricane/cyclone/typhoon.

18. Weather – some basics
Air Pressure Simply the weight of air pressing down onto the surface of the earth.
When air is warm it normally rises and creates an area of low pressure. When it is cool it sinks and creates an area of high pressure.
Pressure is measured on a barometer. It is normally measured in millibars (mb).

19. Wind
Wind is created by air moving from areas of high pressure to areas of low pressure.
This can happen on a local scale or on a global scale

21. Condition 1
Sea surface temperatures must be over 26 degrees centigrade

22. Condition 2
Distance from the equator must be at least 5o north or south of the equator
The Coriolis force is at a maximum at the poles and a minimum at the equator
Hurricanes can not form within 5 degrees latitude of the equator.
The Coriolis force generates a counterclockwise spin to low pressure in the Northern Hemisphere and a clockwise spin to low pressure in the Southern Hemisphere.

23. Condition 3 Low wind shear
This is especially important in the upper levels of the atmosphere
Wind shear is a change in wind speed with altitude
Strong winds at upper altitudes destroy thunderstorms by limiting the upward movement of the air.

24. Formation of tropical storms

25. The Coriolis effect

26. Formation of tropical storms\

27. Questions
Why do hurricanes / typhoons / cyclones form close to the equator?
Why are there strong winds during a typhoon?
Why is there heavy rain during a typhoon?