This week’s weather question deals with the tropics when it regards to the naming process. There are several ways that a tropical cyclone is categorized or named in difference parts of the globe.
The definition defined by the National Hurricane Center (NHC) for a tropical cyclone is: A warm-core non-frontal synoptic-scale cyclone, originating over tropical or subtropical waters, with organized deep convection and a closed surface wind circulation about a well-defined center. Once formed, a tropical cyclone is maintained by the extraction of heat energy from the ocean at high temperature and heat export at the low temperatures of the upper troposphere. In this they differ from extratropical cyclones, which derive their energy from horizontal temperature contrasts in the atmosphere (baroclinic effects).
For a hurricane and typhoon the NHC groups them together based on the meaning, not by the derivation. The definition defined by the NHC is a tropical cyclone in which the maximum sustained surface wind (using the U.S. 1-minute average) is 64 kt (74 mph or 119 km/hr) or more. The term hurricane is used for Northern Hemisphere tropical cyclones east of the International Dateline to the Greenwich Meridian. The term typhoon is used for Pacific tropical cyclones north of the Equator west of the International Dateline.
The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 categorization based on the hurricane’s intensity at the indicated time. The scale provides examples of the type of damage and impacts in the United States associated with winds of the indicated intensity. The following table shows the scale broken down by winds:
Category Wind Speed (mph) Damage
1 74 – 95 Very dangerous winds will produce some damage
2 96 – 110 Extremely dangerous winds will cause extensive damage
3 111 – 129 Devastating damage will occur
4 130 – 156 Catastrophic damage will occur
5 > 156 Catastrophic damage will occur
If you have a weather question you would like an answer send Cody Nickel and email here.