1. Hurricanes One of Natures most powerful and destructive storms

2. Hurricanes are known by many names around the world Cyclones in the Indian Ocean Typhoons in the Western Pacific Hurricanes in the Atlantic and east Pacific

3. Hurricane Season Since hurricanes need warm ocean waters they form during the warmer months. So, hurricane season begins on June 1 st and ends November 30.

4. Recipe for a Hurricane Ingredients:  Warm water. Warmer than 26.5 0 C (81 0 F)  High Relative Humidity. This reduces the amount of evaporation in clouds and maximizes the amount of heat released because there is more precipitation. (water vapor releases heat when it condenses or changes to precipitation). The concentration of heat is critical to driving the system.  Low vertical wind shear. This means that the wind speed does not change with altitude. This allows the storm to grow vertically concentrating the heat released from precipitation in a smaller vertical area. High vertical wind shear would cause the storm to grow over a larger area.  Converging winds (winds blowing towards each other)

5. Procedure First: Start a convection process. The warm ocean waters warm the air above it causing it to rise lifting moisture with it This starts the convection process. The red arrows show warm air rising and the blue arrows show cooler air sinking.

6. Second: Add converging winds. These create a cyclone, or low pressure area, increasing convection. Click on this link to see how convergence aids in building a hurricane. http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/grow/cisk.rxml http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/grow/cisk.rxml. The pink arrows are the converging winds. The red arrows are warm air rising. The blue arrows are cool air sinking.

7. Fourth: Add low vertical wind shear. This will keep the building storm more upright allowing the energy being created from being spread out over a large area. Click on the link below to see an animation. http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/grow/home.rxml Third: Create a high pressure area aloft. This is done by the release of heat as the water vapor cools and condenses as it rises. The heated air aloft expands and creates the high pressure area

8. Fifth: Wait and watch. The low pressure at the surface and the high pressure aloft creates a “pressure gradient”. This increases the rising motion and the release of heat aloft as condensation occurs. If these conditions continue the storm builds upon itself and a hurricane is made.

9. Stages of Hurricane Development Hurricanes evolve through a life cycle of stages from birth to death. The birth of a hurricane, having only a slight circulation with no closed isobars around an area of low pressure. Tropical disturbances commonly exist in the tropical trade winds at any one time and are often accompanied by clouds and precipitation. Stage one: Tropical Disturbance

10. Stage two: Tropical Depression If sustained winds increase to at least 23 miles per hour, a disturbance is upgraded to a tropical depression. Surface wind speeds vary between 23 miles per hour and 38 miles per hour and a tropical depression has at least one closed isobar that accompanies a drop in pressure in the center of the storm.

11. Stage three: Tropical Storm If sustained wind speeds increase to at least 39 miles per hour, a tropical depression is upgraded to a tropical storm. Surface wind speeds vary between 39 miles per hour and 73 miles per hour and the storm becomes more organized. Tropical storms resemble the appearance of hurricanes due to the intensified circulation.

12. Stage four: H U R R I C A N E As surface pressures continue to drop, a tropical storm becomes a hurricane when sustained wind speeds exceed 74 miles per hour. A pronounced rotation develops around the central core as spiral rain bands rotate around the eye of the storm. The heaviest precipitation and strongest winds are associated with the eye wall. Click on this link to see an animation of how a hurricane forms http://observe.arc.nasa.gov/nasa/earth/hurricane/creation.html http://observe.arc.nasa.gov/nasa/earth/hurricane/creation.html

15. Hurricane Anatomy The eye is found at the center and are between 20-50km in diameter. The eye is the focus of the hurricane, the point about which the rest of the storm rotates and where the lowest surface pressures are found in the storm. Skies are often clear above the eye and winds are relatively light. It is actually the calmest section of any hurricane. Click on this link to watch an animation and explanation of the formation of the eye http://ww2010.atmos.uiuc.edu/( Gh)/guides/mtr/hurr/stages/can e/eye.rxml

16. The Eye Wall Located just outside of the eye is the eye wall. This is the location within a hurricane where the most damaging winds and intense rainfall is found

17. Spiral Bands Radiating outward from the eye wall one can see a banded structure within the clouds. These clouds are called either spiral rain bands (or spiral bands). There are sometimes gaps in between these bands where no rain is found. In fact, if one were to travel between the outer edge of the hurricane to its center, one would normally progress from light rain to dry, back to slightly more intense rain again over and over with each period of rainfall being more intense and lasting longer until reaching the eye.

18. Movement of Hurricanes (Steered by Global Winds)

19. Hurricane Strength

20. Category Wind Speeds mi/hr Storm Surge feet Observed Damage 1 74-95 4-5 some damage to trees, shrubbery, and unanchored mobile homes 2 96-110 6-8 major damage to mobile homes; damage buildings' roofs, and blow trees down 3 111-130 9-12 destroy mobile homes; blow down large trees; damage small buildings 4 131-155 13-18 completely destroy mobile homes; lower floors of structures near shore are susceptible to flooding 5 >"155" >"18" extensive damage to homes and industrial buildings; blow away small buildings; lower floors of structures within 500 meters of shore and less than 4.5 m (15 ft) above sea level are damaged Saffir-Simpson Hurricane Damage-Potential Scale

21. Damage Caused By Hurricanes Winds http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/damg/wind.rxml http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/damg/wind.rxml Storm Surge http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/damg/surg.rxml http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/damg/surg.rxml Heavy Rain and Flooding Tornadoes Rip Tides http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/damg/rip.rxml http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/damg/rip.rxml

22. Public Awarness

23. 2005 Hurricane Season