1. Hurricane

2. 2 Conditions needed for Hurricane to Form
A Hurricane contains Multiple Thunderstorms
2) Warm water* is the fuel that powers hurricanes - it evaporates and feeds the convection updrafts.
1) Light Winds Aloft:
No high altitude shear to stop convection
* 2b) Ocean temperatures must be warmer than 80o to a depth of 200 feet.

3. Hurricane Elena from space
Hurricanes can be the size of several states!

4. Hurricane Eye - Calm Air sinks and warms above the dew point.
The eye is clear and calm down to the surface.
Pressure hits rock bottom! (below 900 mb)

5. Eye Wall – highest winds
The wall of the eye contains the highest winds and violent updrafts.

6. Eye Wall – highest winds
Minimum wind speed for a hurricane is
74 mph. Strongest ever – Hurricane Gustav (2008) – hit Cuba at 211 mph !!

7. Hurricane Circulation
Air spirals in to the hurricane at the bottom and spirals out of the hurricane at the top. Clouds are created by updrafts reaching the dew point altitude and clear spaces are created by descending air warming and evaporating.

8. Hurricane Structure
Air spirals counterclockwise in to the hurricane at the bottom and spirals clockwise out of the hurricane at the top.
Rainbands / Clouds are created by updrafts quickly reaching the dew point altitude.

9. Hurricane Structure
Air spirals in to the hurricane at the bottom and spirals out of the hurricane at the top.

10. Wind Speed and Pressure
The eye of the hurricane has the lowest pressure and winds are almost calm.
The eye wall has the has much higher pressure than the eye and the highest wind speeds in the whole hurricane.

11. Hurricane Katrina

12. Hurricane Katrina
130 mph winds hit here.
Winds that hit here were only about 70 mph.
Hurricane Katrina devastated the Gulf Coast and New Orleans in late August, Winds and rain were especially strong on the east side of the storm.

13. Katrina makes landfall
Hurricane Katrina makes landfall on the Louisiana and Mississippi shoreline.

14. Storm Surge
The wind driving the water towards shore along with the low pressure at the eye of the storm creates a bulge on the ocean surface called the storm surge.

15. Storm Surge
Above: When you add a 15 foot storm surge to the normal 2 foot tide, you get a 17 foot high storm tide.
Hurricane Katrina had a 24 foot high storm surge along the Mississippi shoreline and an 18 foot high storm surge along the Louisiana shoreline.

16. Storm Surge Erosion – Ouch!!

17. New Orleans, 2005
In addition to the storm surge, New Orleans and surrounding areas were inundated with an 8” – 10” deluge of rain falling at a rate of over an inch per hour at times.

18. New Orleans – before and after

19. New Orleans after Katrina

20. Hurricane Sandy, 2012

21. Hurricane Sandy, 2012
Hurricane Sandy collided with a polar cold front snowstorm Hurricanes with snow are unusual, to say the least! The interaction of two such storms is called the Fujiwhara effect

22. Hurricane Sandy Storm Surge
Sandy’s storm surge was over 14 feet in New York and northern New Jersey, but only – 8 feet in Delaware and southern New Jersey

23. Hurricane Sandy, 2012
New Jersey coastline

24. Hurricane Sandy, 2012
New Jersey coastline

25. Hurricane Sandy, 2012
New Jersey coastline

26. Hurricane Sandy, 2012
New Jersey coastline

27. Seaside heights Amusement Park
New Jersey coastline

28. I Think I’ll take the Next Train!
Manhattan

29. I Think I’ll take the Next Train!
Manhattan Subway

30. Bogus Hurricane Sandy Photos

31. Bogus Hurricane Sandy Photos