ties is being hurled high into the air after “wiping out” and then falling head-first
into shallow water. The result can be a broken neck and permanent paralysis,
assuming the surfer does not drown in the turbulent water.
As a severe hurricane nears, the swell frequency can drop to 6/min or less.
The thundering of the breakers can sometimes be heard for hundreds of meters
inland. There is also a shift in the wind. In the northern hemisphere, the wind
backs (shifts counterclockwise as viewed from above) about 90° as the storm
nears, so that as you stand directly facing the oncoming breakers, the wind blows
against the left side of your body. In the southern hemisphere, the wind turns
clockwise about 90°; as you look at the oncoming waves, the wind blows from
your right. As the waves break, the wind blows the spray laterally through the
air. When a hurricane moves on a track more or less directly toward you, the
waves become continually larger, and the direction from which they come does
not change significantly. If the storm is not moving directly toward you, the
direction from which the waves arrive slowly rotates clockwise or counter-
clockwise, depending on whether the eye is traveling toward your right or
toward your left as you face the sea.
Ocean swells do not always arrive perpendicular to the beachfront. They can
come in at a considerable angle. This is when littoral and rip currents are most
likely to arise. If the swells are large, beach erosion occurs. Such swells can
wash away much of the shoreline within a day or two. Houses are damaged,
roads undermined, and inlets filled in with sand.
TORNADOES AND MICROBURSTS
The wind damage from a hurricane results mainly from the prolonged, violent
“blow” in the eyewall. Few hurricanes retain deadly wind speeds farther than
about 160 km (100 mi) inland, although this depends to a large extent on the ter-
rain, and considerable damage can still result from sustained winds of 50 to 60 kt
(about 60 to 70 mi/h). Hurricanes can produce tornadoes, however, and these
have higher wind speeds than those in the general circulation of the eyewall.
Tornadoes are most frequently observed in the forward semicircle of a hurri-
cane, especially in the right front quadrant. But they can take place anywhere in
the rainbands or eyewall the storm. In a hurricane, a tornado may move much
faster than a typical “Texas twister,” and can strike with little or no warning. The
tornadoes associated with a tropical hurricane are, however, rarely as large or vio-
lent as their continental counterparts. Hurricane-spawned tornadoes can neverthe-
less tear the roofs off of buildings, shatter windows, overturn automobiles, strip
trees, and cause other serious damage to property. As the hurricane moves into the
temperate latitudes, the tornadoes may become more violent. Hurricane Camille,
CHAPTER 6 Tropical Cyclones
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