Hurricanes: Their Nature and Impacts on Society - Climate Science ...

CHAPTERS
When a hurricane forms, it poses a significant danger to society. The importance
<strong>and</strong> danger of tropical cyclones differ between l<strong>and</strong> <strong>and</strong> water. Over the
oceans, the human activities <strong>and</strong> assets at risk are primarily oil rigs, shipping,
<strong>and</strong> air traffic. On l<strong>and</strong>, particularly along the coast, cities, towns, <strong>and</strong> industrial
activities become threatened. <strong>Hurricanes</strong> also have ecological impacts
(e.g. Lodge 1994). This chapter overviews the physical impacts of a hurricane
over the ocean, at l<strong>and</strong>fall, <strong>and</strong> inl<strong>and</strong>. It also discusses societal impacts <strong>and</strong>
how they are measured <strong>and</strong> understood.
5.1 OCEAN IMPACTS
Winds of hurricane speed over the ocean are characterized by blowing spray
over a white, foaming sea state of large waves. Monstrous waves can develop
in this environment. For example, in 1995, the cruise ship Queen Elizabeth II
was rocked by a 70 foot (21 meter) wave caused by distant Hurricane Luis.
The sea near a hurricane is chaotic, <strong>and</strong> an extreme hazard to shipping can
occur in response to wave motion moving in many directions. The heights of
the maximum ocean waves that were associated with Hurricane Kate in the
eastern Gulf of Mexico in November 1985 are illustrated in Figure 5.1, along
with other observed meteorological characteristics. These measurements were
made from an unmanned ocean buoy. Wave height was determined by
monitoring the movement of the buoy by the waves. In this storm, wave
heights of greater than 38 feet (12 meters) were observed preceding the
passage of the eye on 20 November.
For comparison, strong winds, of course, also occur in winter storms over the
open ocean. The risk to shipping <strong>and</strong> other activities from wave action,
however, is generally less serious in such storms for two reasons. First, the wind
blows primarily in one direction in a given sector of a winter storm. Hence the
waves move in concert with the wind. A ship can thus orient itself to minimize
the effect of the waves. In a hurricane, winds change direction rapidly around
the eye. The result is a chaotic sea with swells <strong>and</strong> waves propagating in a
myriad of directions. A ship cannot simply steer into the running sea in order to