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The terms hurricane and typhoon are regionally specific names for a strong "tropical cyclone". A tropical cyclone is the generic term for a non-frontal synoptic scale low-pressure system over tropical or sub-tropical waters with organized convection (i.e. thunderstorm activity) and definite cyclonic surface wind circulation ^{[1] [2]} Naming conventions are^[1]:

• hurricane (the North Atlantic Ocean, the Northeast Pacific Ocean east of the dateline, or the South Pacific Ocean east of 160E)
• typhoon (the Northwest Pacific Ocean west of the dateline)
• severe tropical cyclone (the Southwest Pacific Ocean west of 160E or Southeast Indian Ocean east of 90E)
• severe cyclonic storm (the North Indian Ocean)
• tropical cyclone (the Southwest Indian Ocean)

A typhoon or tropical storm is a tropical cyclone that forms in the northwestern Pacific Ocean. The basin is demarcated within the Pacific Ocean from Asia, north of the equator, and west of the International Date Line.^[3] Storms from the Eastern and Central Pacific crossing the date line are re-designated as typhoons; prior to entering the basin they are respectively called "hurricanes" and "severe tropical cyclones."^[4] This basin features the strongest cyclones on record.

Typhoon seasons include the entirety of the calendar year. Most storms tend to form between May and November, although they can occur at other times of the year as well.

[edit] Etymology

The word "typhoon" may come from the Hakka dialect phrase "tai foong", or the Cantonese phrase "dai fung", or the Mandarin "taí fēng," all with the meaning "Big Wind" (simplified Chinese: 大风; traditional Chinese: 大風; pinyin: dàfēng).^[5]

Other possible origins of the word include the Greek Typhon, the god of the winds, who personifies storm thunder winds. The Arabic, Persian, and Hindi terms tufan may have been borrowed from the Greek.^[6] In old Turkic script the word Tufan is also recorded.

In current Mandarin Chinese, typhoon is táifēng (simplified Chinese: 台风; traditional Chinese: 颱風; pinyin: táifēng; Cantonese Jyutping: toi⁴fung¹), and in Japanese it is taifū (台風^?).

[edit] Climatology

Nearly one-third of the world's tropical cyclones form within the Western Pacific. This makes this basin the most active.^[7] Pacific typhoons have formed year round, with peak months from August to October. The peak months correspond to that of the Atlantic hurricane seasons. Along with a high storm frequency, this basin also features the most globally intense storms on record. One of the most recent extraordinary years was 1962.

[edit] Paths

Tracks of all tropical cyclones in the northernwestern Pacific Ocean between 1980 and 2005. The vertical line to the right is the International Date Line.

Typhoon paths follow three general directions.^[7]

• Straight. A general westward path affects the Philippines, southern China, Taiwan, and Vietnam.
• Recurving. Storms recurving affect eastern China, Taiwan, Korea, and Japan.
• Northward. From point of origin, the storm follows a northerly direction, only affecting small islands.

[edit] Basin monitoring

The following agencies monitor typhoons:

• Joint Typhoon Warning Center
• Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA)
• RSMC Tokyo-Typhoon Center, part of the Japan Meteorological Agency

[edit] Name sources

The list of names consists of entries from 17 East Asian nations and the United States who have territories directly affected by typhoons. The submitted names are arranged into five lists; and each list is cycled with each year. Unlike hurricanes, typhoons are not named after people. Instead, they generally refer to animals, flowers, astrological signs, and a few personal names. However, PAGASA retains its own naming list, which does consist of human names.^[3] Therefore, a typhoon can possibly have two names. Storms that cross the date line from the Central Pacific retain their original name, but the designation of hurricane becomes typhoon. In Japan and Vietnam, typhoons are simply numbered according to the sequence of their occurrence in the calendar year. Hence the third typhoon in a given year is simply "Typhoon No. 3".

[edit] See also

Tropical cyclones portal

• Tropical cyclone

[edit] References

[edit] External links

• Unisys Data