Hurricanes in the Southern Hemisphere

Factual Questions
1

As I wait for the arrival of yet another hurricane down here in Florida, two questions come to mind:

  1. Why is it that hurricanes never hit south of the Equator?

  2. What are the real estate prices down there? :slight_smile:

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url==http://mpittweather.com/southemp.htm]They do. You don’t hear about them at the same time we’re experiencing them, because their hurricane season is displaced by 6 months from ours.

3

Crap. Fixed link.

4

From Hurricanes Faq:

Exciting Real Estate Opportunities In Rio de Janeiro, Brazil

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They aren’t called “hurricanes” in the southern hemisphere: they are called “tropical cyclones”. In 1974, Darwin (the capital of the Northern Territory of Australia) was destroyed by a cyclone, and most of the population was evacuated.

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There are several “regions” where tropical cyclones (hurricanes, typhoons) develop: Northern Atlantic, Eastern North Pacific, Central North Pacific, Western North Pacific, Western Australian Region, Northern Australian Region, Eastern Australian Region, Fiji Region, Philippine Region, Papua New Guinea Region, Southwest Indian Ocean. Each has its own naming system. (http://www.nhc.noaa.gov/aboutnames.shtml)

The Southern Atlantic doesn’t have a naming system because the tropical depressions that form there rarely get up to the strength where other depressions get named. They usually hit South America way too soon, and lose strength.

The North-of-the-Equator tropiocal cyclone seasons are 6 months offset from the South-of-the-Equator seasons. Also, northern cyclones rotate counterclockwise; southern ones rotate clockwise.

Storms that form in the north cannot venture into the Southern Hemisphere and vice versa, else the Corriolis (sp?) Effect would cause them to break up.

7

Actually, here’s a more accurate explanation of why the South Atlantic rarely gets hurricanes, from http://www.aoml.noaa.gov/hrd/tcfaq/G7.html .

*In March, 2004 a hurricane DID form in the South Atlantic Ocean and made landfall in Brazil. But this still leaves the question of why hurricanes are so rare in the South Atlantic. Though many people might speculate that the sea surface temperatures are too cold, the primary reasons that the South Atlantic Ocean gets few tropical cyclones are that the tropospheric (near surface to 200mb) vertical wind shear is much too strong and there is typically no inter-tropical convergence zone (ITCZ) over the ocean (Gray 1968). Without an ITCZ to provide synoptic vorticity and convergence (i.e. large scale spin and thunderstorm activity) as well as having strong wind shear, it becomes very difficult to nearly impossible to have genesis of tropical cyclones.

In addition, the US National Hurricane Center has documented the occurrence of a strong tropical depression/weak tropical storm that formed off the coast of Congo in mid-April 1991 (McAdie and Rappaport (1991)) . This storm lasted about five days and drifted toward the west-southwest into the central South Atlantic. So far, there has not been a systematic study as to the conditions that accompanied this rare event.*