Sunday, 18 November 2012

Science Fact : Sandy - Hurricane, typhoon or cyclone?





Cyclone, typhoon and hurricane are different names for the same basic weather phenomenon.  It is normally accompanied by torrential rain and maximum sustained wind speeds (near centre) exceeding 119 kilometers per hour:

  • Hurricanes - In the western North Atlantic, central and eastern North Pacific, Caribbean Sea and Gulf of Mexico
  • Typhoons - In the western North Pacific.
  • Cyclones - In the Bay of Bengal and Arabian Sea.
  • Severe tropical cyclones - In western South Pacific and southeast India Ocean.
  • Tropical cyclones - In the southwest India Ocean.
 



Typhoons and hurricanes and cyclones all rotate in the same direction, counterclockwise, if they form in the Northern Hemisphere.  Clockwise-rotating storms are more common in the Indian Ocean and off the coast of Australia.




Reason to Name Tropical Cyclones

Tropical cyclones are given short and distinctive names instead of latitude-longitude identification methods to reduce confusion when two or more tropical storms occur at the same time.  The name list is proposed by the National Meteorological and Hydrological Services (NMHSs) of WMO (World Meteorological Organization) Members of a specific region, and approved by the respective tropical cyclone regional bodies at their annual/bi-annual sessions.




Predicting Tropical Cyclones

Meteorologists around the world use modern technology such as satellites, weather radars and computers etc. to track tropical cyclones as they develop. Tropical cyclones are often difficult to predict, as they can suddenly weaken or change their course. However, meteorologists use state-of-art technologies and develop modern techniques such as numerical weather prediction models to predict how a tropical cyclone evolves, including its movement and change of intensity; when and where one will hit land and at what speed. Official warnings are then issued by the National Meteorological Services of the countries concerned.

Hurricane Sandy was difficult to understand at first. The National Weather Service (USA) uses several computer models to predict a hurricane's path. When the models agree, predictions are more certain; when they have different outcomes, forecasters are unsure what will happen. In Sandy's case, the models initially disagreed about whether the storm would veer off to sea or make for land. By Oct. 25, however, the differences began clearing and by Oct. 27, all the models agreed that Sandy was heading toward the U.S. mainland.




When do tropical cyclones occur?


The typhoon season in the western North Pacific region normally runs from May to November. The Americas/Caribbean hurricane season runs from June 1 to November 30, peaking in August and September. The cyclone season in South Pacific and Australia normally runs from November to April. In the Bay of Bengal and Arabian Sea, tropical cyclones usually occur from April to June, and September to November. The East Coast of Africa normally experiences tropical cyclones from November to April.



How about Malaysia?

Do we experience any tropical cyclones?  
 How about monsoon, is it similar to tropical cyclones?



References

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