Why Hurricanes Never Cross the Equator
Hurricanes have never crossed the equator due to the Coriolis force, which is nearly absent at this line of latitude. The closest recorded storm was Typhoon Vamei in 2001, which formed just 1.4 degrees North. The lack of tropical storms in the southeastern Pacific is attributed mainly to colder ocean temperatures and strong wind shear.
It may surprise some, but no hurricane has ever crossed the equator. This phenomenon is rooted in a basic meteorological principle related to the Earth’s rotation known as the Coriolis force. It essentially dictates the behavior of winds in tropical storms, defining their rotation and movement depending on which hemisphere they occupy.
Hurricanes and tropical storms typically rotate counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere, thanks to the Coriolis force. However, at the equator, this force is near zero. Consequently, this means a tropical system cannot transition from one hemisphere to another, making such a crossing impossible.
The closest any tropical storm has come to crossing the equator was Typhoon Vamei in 2001. This storm made its formation at just 1.4 degrees North latitude, coming within an eye-watering 100 miles of the equatorial line in the western Pacific. This amount of closeness establishes a marker of sorts in the realm of tropical storms.
Interestingly, an unnamed tropical depression managed to form even closer to the equator in December 1973, at 0.5 degrees latitude. This storm later strengthened into a tropical storm at approximately 0.7 latitude, but the U.S. National Hurricane Center disputes that, noting that the storm did not reach tropical-storm-force winds until it had moved north of 10 degrees latitude. Such discrepancies occur because different meteorological organizations employ varying methods for assessing storm wind intensity.
Looking at maps of global tropical cyclones reveals another truth: there is a glaring absence of tropical storms in the southeastern Pacific, particularly west of South America. In fact, only one hurricane has ever formed in that region—a 2004 storm dubbed ‘Catarina’—and history shows only two other tropical storms appeared in the southern Atlantic basin since then, in 2010 and 2011. The remaining storms pictured on these maps are classified as subtropical.
Experts suggest that the main reason for the infrequency of storms off the South American west coast is largely due to colder oceanic waters. The Peru Current, which flows northward along the coast, keeps sea temperatures lower than what is necessary for tropical storm formation (which is around 26 degrees Celsius). DaSilva emphasizes this situation, noting that while Brazil’s offshore waters are warmer, the wind shear tends to disrupt development before storms can gain strength.
In summary, hurricanes have never crossed the equator, primarily due to the Coriolis force, which is virtually absent at the equator. While Typhoon Vamei holds the record for coming closest, only a couple of tropical systems have approached the equatorial line. Factors such as colder waters and higher wind shear off the South American coast further explain the scarceness of storms in this region, underscoring the unique dynamics of tropical cyclone formation.
Original Source: www.accuweather.com
