Last week, Hurricane Matthew was a Category 5 storm. In 2008, some described the financial meltdown as a Category 5 economic storm. How did “5” come to stand for devastating?
On one level, this story of the Saffir-Simpson Hurricane Wind Scale—that terrifying or reassuring gage predicting whether a hurricane will cause some damage—Category 1—or probably destroy your home—Category 5—is a technological tale. It’s about data collected by Geostationary (GOES) satellites, U.S. Air Force and National Oceanic and Atmospheric Administration hurricane reconnaissance aircraft, ships, buoys, and radar processed to offer a one-minute average that is roughly logarithmic in wind speed, with the top wind speed expressed as 83x10^(c/15) miles per hour rounded to the nearest multiple of 5. But the Saffir-Simpson scale is also a story of two experts who themselves survived catastrophes before collaborating on this now ubiquitous measurement.
When Robert Homer Simpson was 6 years old, he survived the Corpus Christi, Texas, hurricane of 1919—but one relative and 770 other people did not. Disaster struck during Sunday dinner. “Not only was there vast wreckage everywhere but houses, still intact, were afloat, many with refugees clinging to them,” he would recall. Perched on the sixth floor of the local courthouse, Simpson saw a man drown trying to save his baby.