1. Hurricane Basics
For more detail than you probably will ever need or want, go to my webpage, to Links, and to Hurricanes.
There you will find information about hurricane names, hurricane records, and much more.

2. Hurricane Facts:
Tropical storms need warm water(at least 80 degrees) to grow.
Evaporation of warm water releases the stored heat energy into the air when it condenses(“latent heat of condensation”)
An average hurricane uses as much energy in a day as the entire US in 6 months.
Their “good side”: hurricanes help maintain the heat balance of the Earth.

3. More hurricane Facts:
Hurricanes move with large currents of air in the atmosphere. The direction of the storm is not altered by land masses, but its strength is diminished over land.
Hurricanes can not be stopped with technology such as nuclear weapons or cloud seeding (a better strategy: get out of the way!)

4. Hurricanes are violent tropical storms.
Air is warm and moist throughout.
Have no fronts because only one air mass is involved.
Low pressure systems with wind, clouds, and rain to the max.
Contrast with middle-latitude cyclones like we get here.

7. Storm #2

8. L

9. Hurricanes have three main parts.
Spiral Rain Bands
Thunderstorms arranged in rows forming a big spiral.
Surface wind pattern is counterclockwise and toward center (convergent).
Eyewall
Strongest wind, heaviest rain.
Eye
Lowest pressure, light winds, descending airflow, basically clear sky above.

10. Low pressure at the surface pulls air in counter-clockwise.
High pressure aloft expels the air in a clockwise direction.

11. Winds are breezy at the edge of the storm and increase to a maximum in the eyewall. Winds are relatively light in the ‘eye’ itself.

12. . How variables change across a hurricane
Pressure –decreases inward, lowest in eye
Wind speed – increases to max. in eyewall
Rainfall - increases to max. in eyewall
Storm surge – max. on side of hurricane with onshore winds (right-hand side of eye relative to direction of storm track in N. Hemisphere)

13. How are hurricanes compared?
Minimum central barometric pressure
Which determines
Maximum sustained wind speed
Which leads to
Height of storm surge
Which is the deadliest effect of hurricanes.

14. Stages of development of tropical cyclones
Tropical disturbance
unorganized cluster of thunderstorms
sustained wind speed 0 to 19 knots
Tropical depression
cluster of thunderstorms with associated pressure drop
sustained wind speed 20 – 33 knots
assigned a number
Rated using the Saffir-Simpson scale

15. Stages of development of tropical cyclones (continued)
sustained wind speeds at least 34 knots , but < 64 knots
assigned a name
Hurricane
sustained wind speed 64 knots (74 mph) or more
keeps the same name as assigned

16. Warm surface ocean temperatures (at least 80º F)
“What environmental conditions are necessary for a tropical depression to develop into a tropical cyclone?”
Warm surface ocean temperatures (at least 80º F)
Sufficient quantity of this warm water (~ 200 feet thick or more….Why?)
Weak vertical wind shear (just the opposite of what forms severe non-tropical thunderstorms, where directional wind shear enhances rotation)
Location is at least 5º from the equator so that the Coriolis effect is acting to produce rotation.

17. The Saffir-Simpson Hurricane Scale
Sustained Storm Resulting
Winds Surge Damage
Category mph ft Trees/PowerDown
Category mph ft Sign, roof & building damage
Category mph ft Widespread damage/flooding
Category mph ft Buildings destroyed/damaged
Category mph ft Catastrophic damage,flooding
3, 4 & 5 are major hurricanes!

18. Hurricane archives
To get a glimpse of unpredictability, follow the track of Hurricane Ivan. And Jeanne.
2011 was an “easy” season, unlike
2005 which was a record year for U.S. hurricanes! Dennis Katrina Rita Stan Wilma Comparing years for hurricane seasons

19. How do Hurricanes Destroy?
Strong winds!
Torrential rain!
Storm surge!
Ferocious surf!

20. 2 x WIND = 4 x FORCE Wind knocks down trees & power lines.
Long duration, shifting and gusting winds.
Propels objects into windows and walls.
Wind slowly dismantles homes/buildings.
95% of Hurricane Andrew (1992) damage was wind related.
Hurricane-force winds can occur independent of a true hurricane

21. Hurricane-force wind is ferocious and continuous.

22. NO Electricity!
Lights, air conditioning, refrigeration, cooking, fans, television, stoplights, gas pumps, computers, clocks, banks (ATMs), electric charging devices, hairdryers, coffee makers, freezers, stereos, most stores, most businesses, garage door openers, and so on….

23. HEAVY
RAIN
AND
FLOODING
Can wash out bridges

24. Rainfall: The records are “tens of inches” per day!
Slow moving storms can easily dump inches of rain over a wide area. Debris clogs sewers and drainage ways.
Flood waters contaminate drinking water
High water forces insects, rats, and other wild critters to higher ground (same place you want to be).
Wind but not flood damage is covered by home owner’s insurance! You would need special coverage.

25. STORM SURGE

26. STORM SURGE
Low pressure and converging winds raise sea levels under the hurricane. When the hurricane makes landfall, so does the higher sea level.
Powerful waves ride on top of the surge. More waves
Storm surge destroys coastal buildings (more) and inundates barrier islands.

27. STORM SURGE
Storm surge can travel well inland through harbors, rivers, creeks and canals.
Storm surge is responsible for the greatest loss of life from a natural disaster in US history, Galveston Island (Texas), where is 1900 at least 8,000 died. Galveston was hit again by Hurricane Ike in 2008.

28. One more thing:
Hurricanes often produce tornadoes, like this one during hurricane Danny ! ( hurricane + tornado = a pretty bad day )

29. How to save your car in a hurricane…