1. Hurricanes!

3. Figure 15.3
A model that shows a vertical view of air motions and clouds in a typical hurricane in the Northern Hemisphere. The diagram is exaggerated in the vertical.

4. FIGURE 15.9 The top diagram shows an intensifying
tropical cyclone. As latent heat is released
inside the clouds, the warming of the air aloft creates
an area of high pressure, which induces air to
move outward, away from the high. The warming of
the air lowers the air density, which in turn lowers
the surface air pressure. As surface winds rush in
toward the surface low, they extract sensible heat,
latent heat, and moisture from the warm ocean. As
the warm, moist air flows in toward the center of the
storm, it is swept upward into the clouds of the eyewall.
As warming continues, surface pressure lowers
even more, the storm intensifi es, and the winds blow
even faster. This situation increases the transfer of
heat and moisture from the ocean surface. The middle
diagram illustrates how the air pressure drops
rapidly as you approach the eye of the storm. The
lower diagram shows how surface winds normally
reach maximum strength in the region of the
eyewall.

5. Figure 15.4
The cloud mass is Hurricane Katrina’s eye wall, and the clear area is Katrina’s eye photographed inside the eye on August 28, 2005, from a NOAA hurricane hunter aircraft. For a satellite image of the storm on this day, look at the opening photo on p. 404.
Fig. 15-4, p. 408

6. Figure 15.5
A three-dimensional satellite view of Hurricane Katrina passing over the central Gulf of Mexico on August 28, The cutaway view shows concentric bands of heavy rain (red areas inside the clouds) encircling the eye. Notice that the heaviest rain (largest red area) occurs in the eye wall. The isolated tall cloud tower (in red) in the northern section of the eye wall indicates a cloud top of 16 km (52,000 ft) above the ocean surface. Such tall clouds in the eye wall often indicate that the storm is intensifying.

7. Figure 15.6
Arrows show surface winds spinning counterclockwise around Hurricane Dora situated over the eastern tropical Pacific during August, Colors indicate surface wind speeds. Notice that winds of 80 knots (92 mi/hr) are encircling the eye (the dark dot in the center). Wind speed and direction obtained from QuikSCAT satellite. (NASA/JPL)

8. Progression of Tropical Events
Easterly Wave (Tropical Disturbance)
Tropical Depression
Tropical Storm
Hurricane
10-25%
50-60%

9. Easterly Wave
FIGURE 15.1 A tropical wave (also called an easterly wave)
moving off the coast of Africa over the Atlantic. The wave is shown by
the bending of streamlines — lines that show wind fl ow patterns.
(The heavy dashed green line is the axis of the trough.) The wave
moves slowly westward, bringing fair weather on its western
side and rain showers on its eastern side.

11. FIGURE 15.10 Visible satellite image
showing four tropical systems, each in a different
stage of its life cycle.

12. Figure 15.10
Regions where tropical storms form (red shading), the names given to storms, and the typical paths they take (red arrows).

13. Tropical Cyclones and Sea-Surface Temperatures
Fixes
80°F Water
Temperature
June/July
August
September

14. FIGURE 15.8 The total number
of hurricanes and tropical storms (red
shade) and hurricanes only (yellow
shade) that have formed during the past
100 years in the Atlantic Basin — the
Atlantic Ocean, the Caribbean Sea, and
the Gulf of Mexico. (NOAA)

16. Hurricane Georges

17. Atlantic Basin Hurricane Satellite Loops
2005 season
(start at 1:00)
2010 season
(Igor, 2:40)

18. FIGURE Regions where
tropical storms form (orange shading),
the names given to storms, and the
typical paths they take (red arrows).

19. H H H H

20. GLOBAL TROPICAL CYCLONES
1985–2005

22. COASTAL HURRICANE VULNERABILITY
> 50 years
between landfall
< 20 years

23. Damage
Wind
Tornadoes
Flooding
Storm Surge

24. FIGURE The changing of the ocean level as different category hurricanes make landfall along the coast. The water typically
rises about 4 feet with a Category 1 hurricane, but may rise to 22 feet (or more) with a Category 5 storm.

25. # U.S. Landfalling Hurricanes, 1900–2007
FIGURE The number of hurricanes (by each category)
that made landfall along the coastline of the United States from 1900
through All of the hurricanes struck the Gulf or Atlantic coasts.
Categories 3, 4, and 5 are considered major hurricanes.

26. % Rainfall (May-Nov) from Tropical Cyclones
Knight and Davis, 2007

27. ANNUAL NUMBER OF NORTH ATLANTIC TROPICAL CYCLONES

28. When do the storm counts become reliable?

30. Global Tropical Cyclones: 1971–2014

31. Hurricane Development Factors
High Water Temperatures
Unstable lower atmosphere
Moisture convergence at surface
Lack of vertical wind shear
Warm
Cool up L up
Wind

32. Deadliest U.S. Hurricanes
(Blake et al., 2011)

33. Costliest U.S. Hurricanes, 1900-2010
(Blake et al., 2011; damages not inflation-adjusted)

34. Costliest U.S. Hurricanes, 1900-2010
(Blake et al., 2011; damages are inflation-adjusted)

35. U.S. Total Losses per Year from Atlantic Tropical Cyclones
( )
An Upward Trend?
(Source: Pielke Jr.,R., 2006, Oceanography, 19, )

36. Normalized U.S. Losses per Year from Atlantic Tropical Cyclones
( )
No change when population demographics are properly considered
(Source: Pielke Jr.,R., 2006, Oceanography, 19, )