Hurricanes!

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.

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.

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

Figure 15.5 A three-dimensional satellite view of Hurricane Katrina passing over the central Gulf of Mexico on August 28, 2005. 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.

Figure 15.6 Arrows show surface winds spinning counterclockwise around Hurricane Dora situated over the eastern tropical Pacific during August, 1999. 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)

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

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.

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

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

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

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)

Hurricane Georges

Atlantic Basin Hurricane Satellite Loops 2005 season http://www.youtube.com/watch?v=0woOxPYJz1U&feature=related (start at 1:00) 2010 season http://www.youtube.com/watch?v=ual22znKM10&feature=related (Igor, 2:40)

FIGURE 15.11 Regions where tropical storms form (orange shading), the names given to storms, and the typical paths they take (red arrows).

H H H H

GLOBAL TROPICAL CYCLONES 1985–2005

COASTAL HURRICANE VULNERABILITY > 50 years between landfall < 20 years

Damage Wind Tornadoes Flooding Storm Surge

FIGURE 15.16 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.

# U.S. Landfalling Hurricanes, 1900–2007 FIGURE 15.17 The number of hurricanes (by each category) that made landfall along the coastline of the United States from 1900 through 2007. All of the hurricanes struck the Gulf or Atlantic coasts. Categories 3, 4, and 5 are considered major hurricanes.

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

ANNUAL NUMBER OF NORTH ATLANTIC TROPICAL CYCLONES

When do the storm counts become reliable?

http://www.ncdc.noaa.gov/monitoring-content/sotc/tropical-cyclones/2015/annual/NAT_storms_2015.png

Global Tropical Cyclones: 1971–2014

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

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

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

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

U.S. Total Losses per Year from Atlantic Tropical Cyclones (1900-2005) An Upward Trend? (Source: Pielke Jr.,R., 2006, Oceanography, 19, 138-147)

Normalized U.S. Losses per Year from Atlantic Tropical Cyclones (1900-2005) No change when population demographics are properly considered (Source: Pielke Jr.,R., 2006, Oceanography, 19, 138-147)