Typically, tropical cyclones form at least 5.0 degrees of latitude north and south of the equator, or at least 300 nautical miles (556 km, 345 mi) of the equator. Despite the presence of sufficiently warm sea surface temperatures and generally low wind shear, tropical cyclogenesis is uncommon at these latitudes, due to a lack of the Coriolis force, which causes cyclones to spin. On rare occasions, tropical cyclones can develop within 5º of the equator, though it is more prevalent in the northwestern Pacific Ocean.
Background
For centuries, sailors haven't worried about tropical storms near the equator. It's a rule that cyclones are not supposed to develop there.
Dr. Chih-Pei Chang, professor at the United States Naval Research Laboratory[1]
Various factors converge to produce a tropical cyclone, including sufficiently warm sea surface temperatures, low wind shear, ample moisture, and enough atmospheric instability to produce thunderstorms. In addition, weather disturbances typically need to be far enough away from the equator to spin, known as vorticity. This is due to increasing Coriolis force closer to the poles, and which is zero at the equator.[2][3][4] One associated phenomenon often seen with low-latitude cyclones is the equatorial westerly wind burst, which allows for sufficient shear vorticity on both sides of the equator to support tropical cyclogenesis.[5] Westerly wind bursts are typically the most common in the equatorial Western Pacific Ocean.[6]
List
Note: Only systems that were of tropical depression strength or higher within 5.0 degrees of the equator are included.
See also
References
External links
- Steenkamp, Sian C.; G. Kilroy; R. K. Smith (2019). "Tropical cyclogenesis at and near the Equator". Quarterly Journal of the Royal Meteorological Society. 145 (722): 1846–1864. Bibcode:2019QJRMS.145.1846S. doi:10.1002/qj.3529. S2CID 128002922.