Interesting Facts on Typhoons

A hurricane is one of nature's destructive forces.

Typhoons are powerful storms, which develop over water in the Earth's tropical regions. Their destructive swirling winds can reach up to 200 mph and have the ability to cause large-scale destruction. Typhoons, while they form in the tropics, are able to travel and affect a much larger area. Some have been recorded reaching the north Atlantic and even parts of Canada.

Typhoon, Hurricane or Cyclone?

"Typhoon," "hurricane" and "cyclone" are all different names for the same violent, rotating windstorms that form across the globe. They are known as "typhoons" in the northwest Pacific region, "hurricanes" in North and Central America or "cyclones" in the southwest Pacific or Indian Ocean. If a storm is particularly severe it can be known as a "severe cyclonic storm" or "tropical cyclone."

Formation

Hurricanes form in hot, humid conditions over the ocean when winds traveling in opposite directions meet, a phenomenon known as convergence. As the opposing winds collide, hot air is forced upward and cools to form storm clouds. Usually these storms produce nothing more than lightning or a period of heavy rain, but in some cases high pressure and wind in the upper atmosphere can allow the hot air to continue its upward motion for a sustained period, creating a much stronger type of storm. A hurricane's wind is caused by air rushing up from the surface of the ocean to replace air blown away in the upper atmosphere. Due to the Coriolis effect, which can affect the direction water drains down a sink, hurricanes in the northern hemisphere spin anti-clockwise, while in the southern hemisphere they spin clockwise.

Naming Hurricanes

Weather forecasters began naming hurricanes in an attempt to better communicate warnings to the general public. Before 1950 hurricanes were named by the year in which they occurred and a letter from the alphabet, for example 1940A or 1940B. Originally only given female names, in 1978 hurricanes were given male and female names alternately in the East North Pacific storm list and in 1979 on the Atlantic and Gulf of Mexico storm list. There are currently six lists of names for Atlantic hurricanes, each containing 21 names. The names reflect the three major languages spoken in the Caribbean, South and North America: French, Spanish and English. Every six years the lists are recycled and names are replaced when a hurricane name is retired. A name is retired when it is believed recycling it could cause distress or lack of compassion after a particularly deadly or devastating hurricane. In 2005 the name Katrina was retired from use.

Strongest Hurricanes

A category five hurricane is the most severe type of tropical storm. The Saffir-Simpson Hurricane Scale determines a hurricane's category taking into account wind speed and storm surge (the level of disturbance to the ocean surface). For a hurricane to reach category five it must have wind speeds greater than 156 mph and create a storm surge of 18 feet or more. To date only four category five hurricanes have reached land in the U.S., the most powerful of which was the Florida Keys hurricane, which killed 423 people on Labor Day 1935. The most recent was hurricane Katrina in 2005, which reached wind speeds of 175 mph and killed around 1,800 people.

The End of a Hurricane

A hurricane dies out when it moves over cooler water or reaches land, cutting off its supply of warm, humid air. Even with its supply removed, a hurricane can continue to be dangerous and cause serious damage for several hours after reaching land or cool water.

References

• University Corporation for Atmospheric Research: Hurricanes, Typhoons, Cyclones - In Depth
• Environment Canada: Naming Hurricanes
• The National Hurricane Center: The Saffir-Simpson Hurricane Scale & Most Intense Hurricanes in the United States
• Polar Satellite Meteorology and Climatology: The Coriolis Effect
• Atlantic Oceanographic and Meteorological Laboratory: End of Hurricanes

Resources

• The National Hurricane Center