(And by the way, who picked the names Earl and Fiona? Read about it here.)
Part of the drama of hurricane season revolves around the predicting and changing of the severity – or category – of the storm.
There are a few classification scales that meteorological agencies use to determine the intensity of hurricanes. The Saffir-Simpson scale is used to measure the strength of hurricanes in the North Atlantic Ocean and the North-eastern Pacific Ocean. The scale gets it name from the two men who developed it, civil engineer Herbert Saffir and meteorologist Bob Simpson. It was introduced to the general public in 1973.
There are five categories on the scale, which are distinguished by wind speed. For example, in a category-1 hurricane the maximum wind speed is 96 miles. While in a category-5, the wind speed is above 156. Hurricanes of category-3 and above are known as major hurricanes or supertyphoons.
Since recordkeeping began, only three category-5 storms have hit the U.S. The last was Andrew in 1992.
But the power of a category-1 hurricane should not be downplayed. Category-1 hurricanes can cause significant damage, such as uprooting mature trees, ripping off roof shingles, or even toppling mobile homes.
And there’s no guarantee that a higher category hurricane will inflict more damage. For example, a category-2 that strikes an unprepared metropolitan area might wreak more havoc than a category-4 that hits a rural area. To determine the potential for damage, population density, total rainfall, and local terrain all need to be taken into consideration.
Interestingly, it was decided that for this 2010 hurricane season, the experimental Saffir–Simpson Hurricane Wind Scale (SSHWS), which is based on the previously used Saffir-Simpson Hurricane Scale, would be used. The new system is based on wind speed and excludes flood ranges and storm surge estimations.
As you hear meteorologists predict where Earl or Fiona might land, you might wonder why hurricanes move in a particular direction. The answer has to do with the bizarre Coriolis effect, which makes the air in storms rotate counterclockwise in the northern hemisphere and clockwise in the southern hemisphere.