Raining Cats & Dogs
We have all heard the expression "it's raining cats and dogs." There are several theories about this rainfall saying. It is possible that the word cat is derived from the Greek word 'catadupe' meaning 'waterfall.' Or it could be raining 'cata doxas,' which is Latin for 'contrary to experience,' or an unusual fall of rain.
In Northern mythology the cat is supposed to have great influence on the weather, and English sailors still say the cat has a gale of wind in her tail when she is unusually frisky. Witches that rode upon the storms were said to assume the form of cats; and the stormy northwest wind is called the cat's nose in the Harz mountains even at the present day. The dog is a signal of wind, like the wolf. Both animals were attendants of Odin, the storm-god. In old German pictures the wind is figured as the "head of a dog or wolf," from which blasts issue. The cat therefore symbolizes the down-pouring of rain, and the dog the strong gusts of wind that accompany a rainstorm; and a rain of "cats and dogs" is a heavy rain with wind.
The Bible describes a rain of manna and quails more than 3,000 years ago. At the time this was looked upon as a supernatural event; it was actually not an uncommon thing. The rain of manna has happened frequently in modern times; the manna is really a lichen that grows in great numbers after rains.
There are numerous accounts of rains of frogs, hay, fish, and grain. All of these accounts seem to be due to tornado-like "whirlwinds." A good whirlwind can lift thousands of pounds and carry objects for miles. There is one reliable account of a fishing boat that sailed into a large waterspout. Fish flew everywhere. There are about seventy recorded rains of fish, but nearly all of the rains of fish are small ones. There is, however, one account of a fish fall in India in which more than ten people picked up fish weighing up to eight pounds each. There are many accounts of rains of ice-coated ducks, grasshoppers, fish, and frogs, but there is no account of a raining of cats and dogs (Lockhart, 1988). Photo: Courtesy of Pam Rastall
What Are Hurricanes?
Hurricanes are large tropical storms with heavy winds. By definition, they contain winds in excess of 74 miles per hour (119 km per hour) and large areas of rainfall. In addition, they have the potential to spawn dangerous tornadoes. The strong winds and excessive rainfall also produce abnormal rises in sea levels and flooding.
Christopher Columbus was the first European in modern times to write about the hurricane. The Indians of Guatemala called the god of stormy weather "Hunrakan." Similar names were probably present throughout the Caribbean. Captain Fernando de Oviedo gave storms their modern name when he wrote "So when the devil wishes to terrify them, he promises them the 'Huracan,' which means 'tempest.'" The same storms in other parts of the world are known as typhoons, baqulros, Bengal cyclones and willy-willies.
The ocean-water temperature has to be above 79 degrees F in order for a hurricane to be generated, so they normally form in late summer and early fall when the conditions are right. Meteorologists use the term tropical storm when a storm's winds are under 74 miles per hour, and hurricane when the wind speed rises. A hurricane has a peaceful center called the eye, that is often distinctive in satellite images. The eye stretches from 10 to 30 miles wide and often contains calm winds, warm temperatures and clear skies. Around this tropical bliss is a frenzy of winds gusting at speeds up to 186 miles per hour. If one percent of the energy in one hurricane could be captured, all the power, fuel, and heating requirements of the United States could be met for an entire year. It takes 500 trillion horsepower to whirl the great core of winds at such tremendous speeds. It is the equivalent of exploding an atomic bomb every 10 seconds. (Lockhart, 1988).
Left: Image produced by Hasler, Pierce, Palaniappan & Manyin of NASA's Goddard Laboratory for Atmospheres - Data from NOAA
Hurricanes begin as tropical storms over the warm moist waters of the Atlantic and Pacific Oceans near the equator. As the moisture evaporates it rises until enormous amounts of heated moist air are twisted high in the atmosphere. The winds begin to circle counterclockwise north of the equator or clockwise south of the equator. The reatively peaceful center of the hurricane is called the eye. Around this center winds move at speeds between 74 and 200 miles per hour. As long as the hurricane remains over waters of 79F or warmer, it continues to pull moisture from the surface and grow in size and force. When a hurricane crosses land or cooler waters, it loses its source of power, and its wind gradually slow until they are no longer of hurricane force--less than 74 miles per hour.
Hurricanes over the Atlantic often begin near Africa, drift west on the Trade Winds, and veer north as they meet the prevalling winds coming eastward across North America. Hurricanes over the Eastern Pacific begin in the warm waters off the Central American and Mexican coasts. Eastern and Central Pacific storms are called "hurricanes." Storms to the west of the International Date Line are called "typhoons."
Because of the destructive force of hurricanes during late summer and early autumn, scientists constantly monitor them with satellites and sometimes even fly airplane surveillance to keep track of tropical storms that might develop into hurricanes.
Severe weather events are rare extremes in nature that can adversely impact human life and property. It is vital that communities and decision makers have access to all available weather-related hazards information.
Above: The graphic was created by Lynn A. Dombrowski, Ed. D.
NOAA reported more than 25,000 severe weather-related deaths from 1940 through 1991.
Hurricane Intensity & the Saffir-Simpson Scale
Hurricane damage comes not only from wind, but also from rain, tornadoes, floods, and the effects of very low air pressure. So a system that would rank hurricanes by wind force alone would not tell the whole tale.
In the 1970s the Saffir-Simpson hurricane intensity category system was developed to characterize the destructive potential of hurricanes. In addition to maximum sustained wind speed and central pressure, the Saffir-Simpson hurricane categorization includes storm-surge height and coastal destruction potential.
Left: The graphic was created by Lynn A. Dombrowski, Ed. D.
The Saffir-Simpson system sets the levels for hurricanes to five intensity categories, described in this chart under "Damage."
On average, there are about 10 named tropical storms off the east coast of the United States each year. Of these, 6 are likely to develop into hurricanes, but only 2 to 3 are likely to reach Saffir-Simpson category 3 or greater intensity.
Category 5 hurricanes are very rare, occurring about once every one hundred years. Recently, however, there have been several major hurricane events along the east coast of North America. In 1988 Jamaica and Mexico's Yucatan Peninsula were ravaged by category 5 Hurricane Gilbert. In 1989, category 4 Hurricane Hugo landed in Charleston, South Carolina killing 51 people and causing damage of over $6 billion. On August 21, 1992, tropical storm Andrew strengthened to hurricane proportions. Reaching category 5, Andrew was one of the most destructive storms ever recorded along the east coast, destroying more than 63,000 homes, causing $20 billion in property damage, and killing 27 people. Most of the destructive force from hurricanes is caused by high winds. Hurricane Andrew was pushed along by winds in excess of 120 mph. In addition, small whirlwinds were formed near the storm's center, and they picked up speed as they were pulled inward. These whirlwinds led to gusts of up to 80 mph, giving Andrew a destructive force of over 200 mph in some areas.
Experience shows that the use of short, distinctive given names in written as well as spoken communications is quicker and less subject to error than the older more cumbersome latitude-longitude identification methods. These advantages are especially important in exchanging detailed storm information between hundreds of widely scattered stations, coastal bases, and ships at sea.
Since 1953, Atlantic tropical storms have been named from lists originated by the National Hurricane Center. They are now maintained and updated by an international committee of the World Meteorological Organization. The original name lists featured only women's names. In 1979, men's names were introduced and they alternate with the women's names. Six lists are used in rotation. Thus, the 2005 list will be used again in 2011. Here is more information about the history of naming hurricanes.
The only time that there is a change in the list is if a storm is so deadly or costly that the future use of its name on a different storm would be inappropriate for reasons of sensitivity. If that occurs, then at an annual meeting by the WMO committee (called primarily to discuss many other issues) the offending name is stricken from the list and another name is selected to replace it.
Several names have been changed since the lists were created. For example, on the 2004 list (which will be used again in 2011), Gaston has replaced Georges and Matthew has replaced Mitch. On the 2006 list, Kirk has replaced Keith. Here is more information about retired hurricane names.
In the event that more than 21 named tropical cyclones occur in the Atlantic basin in a season, additional storms will take names from the Greek alphabet: Alpha, Beta, Gamma, Delta, and so on. If a storm forms in the off-season, it will take the next name in the list based on the current calendar date. For example, if a tropical cyclone formed on December 28th, it would take the name from the previous season's list of names. If a storm formed in February, it would be named from the subsequent season's list of names.
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Last updated October 14, 2010