Hurricane Categories: The Saffir-Simpson Scale

The movie Twister was a fantastic portrayal of how destructive a cyclone can be. When cyclones involve a specific wind velocity, they are classified as hurricanes. There are various scales put forth by experts to measure the (intensity) of the hurricane. According to the Saffir-Simpson Scale, hurricanes have been classified into five categories, based on the parameters of wind, central barometric pressure and storm surge.

The Saffir-Simpson Hurricane Scale was developed by meteorologist Bob Simpson and civil engineer, Herbert Saffir, in 1971. Incidentally, Bob Simpson was the director of the U.S. National Hurricane Center (NHC), at that time. The scale was developed initially by Saffir, while conducting a study on low-cost housing in hurricane-prone areas. During the course of his study, he realized that there is no simple scale for describing the probable consequences of a hurricane. Drawing a cue from the Richter scale used to measure the intensity of an earthquake, he devised a scale for hurricane based on the wind speed. Saffir later handed over his scale to the NHC, and then Simpson incorporated the storm surge effects and flooding to the scale. The classification of hurricanes, according to the Saffir-Simpson Scale is as follows.

Category 1
In this category, storms have sustained winds of 74 to 95 mph, while the storm surge is around 4-5 ft. These hurricanes usually don't cause any major structural damage to buildings. But, they are powerful enough to uproot or snap trees. They can also topple unanchored mobile homes. In 2008, Hurricane Hanna was a category 1 hurricane.

Category 2
The storms in this category are associated with sustained winds of 96 to 110 mph. Such hurricane result into a storm surge of 6-8 ft. They are strong enough to lift a house and cause structural damage to buildings. Poorly constructed doors and windows can be badly clobbered by a hurricane of this category.

Category 3
In the Atlantic and Eastern Pacific basins, tropical cyclones of category 3 are considered as major hurricanes. It leads to flooding which causes destruction of minor structures near the coastal areas. Utility buildings, especially of wood frame, may undergo structural damage. The root cause of destruction are the winds which hover around the 111-130 mph mark.

Category 4
With sustained winds around 131 to 155 mph, these hurricanes create havoc in fairly populated areas. Mobile homes and normal homes are leveled in such a situation. The huge storm surge, in case of category 4 hurricanes, is 13-18 ft. Roofs of buildings may also undergo major structural damage.

Category 5
According to the Saffir-Simpson Scale, this is the pinnacle a tropical cyclone can reach. The sustained winds can be anything above 156 mph, which is a pointer of the destruction it can cause. Roofs of buildings and homes are totally destroyed, and constructions along the shoreline are completely washed away. Hurricane Felix is an example of a Category 5 tropical cyclone.

These five categories notwithstanding, scientists and newspaper scribes came up with the suggestion of a 6th category after the 2005 Atlantic Hurricane Season. They suggested that this category would be associated with winds greater than 174 or 180 mph. However, Simpson argued that there was no reason for the 6th category to be included as the Saffir-Simpson Scale was designed to evaluate the potential damage caused to man-made structures by a hurricane. According to him, if the wind speed is more than 155 mph, there is bound to be serious damage to a building, in spite of it being excellently built.

Officially, hurricanes that form in the Pacific and Atlantic, east of the International Date Line, are described using the Saffir-Simpson Scale. Ultimately, no matter what the category, there is bound to be extensive damage, when it comes to the people who have actually faced the catastrophe.