1. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 1 Lesson #10 Hurricanes! Vernon Asper USM

2. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 2 Hurricanes! We’ve covered this before but we’re going to review it again with more detail: –Low presure areas –Coriolis deflection –Tropical weather –The ocean’s connection –Hurricane impacts –The future?

3. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 3 Low pressure areas are “low” because the air in them has low density –Warm –Humid (water vapor content) This causes the air to rise This draws air to the center Coriolis causes rotation Accentnetwork.org http://www.air.ky.gov

4. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 4 Lows continue to spin until the low pressure has been equalized (http://www.hi.is/~oi/satellite_photos.htm)

5. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 5 On a weather map, low pressure areas show up as the center of “isobars” where pressure is low in the middle “warm,” rainy conditions usually accompany lows L=992 1008

6. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 6 This all applies to the tropics (near the Equator) But here, things are more complicated Solar heating results in super low pressure WARM HUMID Rising air Clouds form General westward motion http://www.uvi.edu/

7. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 7 As the air mass moves to the west, the flow “flutters” –Like a flag in the breeze The flutters turn to “waveshttp://upload.wikimedia.org http://www.ccrc.sr.unh.edu

8. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 8 Waves can intensify Stronger waves become “depressions” The “depressed” part is because of the low pressure This causes wind to increase By definition, depressions have winds from 28-33 knots http://www.wunderground.com

9. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 9 What causes the storm to intensify? –Water vapor: the storm MUST be over the ocean! –Lack of shear The longer it is over warm water, the stronger it gets Cold water or moving over land will kill it

10. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 10 “Latent Heat” (a review) Latent heat of evaporation is the heat (energy) absorbed by water when it evaporates –Sweating cools you because of this When the water condenses somewhere else, it gives off this heat –Condensation on a window pane Water vapor forming clouds warms the air at that altitude –This feeds the storm

11. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 11 Moist air rises, cools Moisture condenses; warms the air Warmed air rises more, etc. Absolutely depends on moisture (latent heat of evaporation / condensation)

12. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 12 Areas of Tropical Cyclone Formation

13. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 13 Storm Effects Storms have more effect on shaping the shoreline than “normal” conditions Storm surges are extreme high water events Caused by high winds that pile water up along the shoreline.

14. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 14 Hurricane Andrew

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17. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 17

18. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 18

19. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 19

20. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 20 Isaac Katrina

21. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 21

22. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 22

23. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 23

24. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 24 Isaac: 8/29/12

25. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 25 Here are before and after picturesHere are before and after pictures Hurricane Georges (October 1998) removed most of this island.Hurricane Georges (October 1998) removed most of this island. 2002: recovery has started

26. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 26 Project Stormfury 1962- 1983 Can hurricanes be artificially dissipated? YES!!! (well, maybe) These guys seeded several storms with silver iodide Idea was to create ice that would kill the storm It appeared to work but the storms re-intensified when seeding stopped One appeared to change course! www.answers.com

27. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 27 This project and others were all cancelled –They had no “controlled experiment” to prove that they were effective –Computer models indicated that they had had no effect –Funding was pulled Several movies have been made of this: –“Maximum Velocity” –“Storm Tracker”

28. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 28 Climate Change? Possible impacts of Global Warming: 1) warmer oceans –More energy in the oceans means more frequent and more powerful storms 2) higher sea levels –The closer a community is to the beach, the more vulnerable it is to hurricanes This is the logic, but what is the reality? Christmas Island

29. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 29 The total number of hurricanes “may” be increasing But the trend isn’t clear Normal cyclicity? Hurricane strength measurements, west of 69W http://www.climateaudit.org/?p=1000

30. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 30 More people live near the coast We continue to invest in vulnerable areas US Gov’t encourages and subsidizes it! http://maps.csc.noaa.gov/hurricanes/pop.jsp

31. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 31 "Based on a range of models, it is likely that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical SSTs. There is less confidence in projections of a global decrease in numbers of tropical cyclones. The apparent increase in the proportion of very intense storms since 1970 in some regions is much larger than simulated by current models for that period." –http://www.usgcrp.gov (US Global Change Research Program

32. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 32 This year’s forecast: “ We continue to foresee well above-average activity for the 2012 Atlantic hurricane season. “ PROBABILITIES FOR AT LEAST ONE MAJOR (CATEGORY 3-4-5) HURRICANE LANDFALL ON EACH OF THE FOLLOWING COASTAL AREAS: 1) Entire U.S. coastline - 72% (average for last century is 52%) 2) U.S. East Coast Including Peninsula Florida - 48% (average for last century is 31%) 3) Gulf Coast from the Florida Panhandle westward to Brownsville - 47% (average for last century is 30%)

33. ©1996, West Publishing Company (Modified by Asper, 1997; revised by Lohrenz, 2000) Slide 33 Summary Hurricanes are born in the ocean due to the low pressure at the Equator They are intensified by the addition of heat energy through the condensation of water vapor Most predictions for warmer climate expect stronger and possibly more abundant storms in the future Impacts of the storms will be greater as more people live on the coast and as sea level rises