ges can result in considerable loss of life and property. The winds reach their maximum velocity at a radius of 6 to 60 miles from the storm center and diminish rapidly with increasing distance. A radius of 300 mph, wind speed is usually less than 18 mph. The heaviest precipitation occurs under the intense convection in the eyewall. Thunderstorms may produce rainfall rates of 10 inches a day. The release of latent heat associated with this rain maintains low pressure and strong winds. The rapidly whirling movement of hurricane winds can be explained by the conservation of angular momentum. Just as ice skaters spin faster as they bring their arms down, closer to the axis of rotation, so the air rotates faster as it is pulled in toward the center of the storm by the low pressure. Without friction, the wind would increase as the inverse of the distance from the center. Thus, a wind rotating at 3 mph at a radius of 300 mi would have a velocity of 160 mph if it reached a radius of only 6 mi. Friction reduces the predicted speed somewhat, but the basic principle explains the high rotational velocities near the center of the storm. The air that spirals toward the center and rises in the intense convection in the eyewall turns outward in the upper troposphere (about 10 mi above sea level). As the air moves away from the center, its counterclockwise rotation slows, in accord with conservation of angular momentum. At a distance of about 190 mi from the center, the air acquires a clockwise rotation. Hurricanes move with the large-scale wind currents in which they are embedded. The typical speed is 16 mph, but some storms may race along at twice this speed and others can remain stalled in the same location for several days. Typical tracks are from east to west at low latitudes. As the storms approach the continental landmasses, they usually begin to take a more northerly tack. As they reach higher latitudes and come under the influence of t...
