Hurricanes are classified by the SaffirSimpson scale, devised by consulting engineer Herbert Saffir and Dr. Robert H. Simpson, former director of the National Hurricane Center. A storm ranked number 1 is minimal; 2, moderate; 3, extensive; 4, extreme; and 5, catastrophic. Only three hurricanes in this century have been classed as number 5: the 1935 Labor Day storm that ravaged the Florida Keys, Camille in 1969, and Allen, 1980’s first great storm. Since 1900, hurricanes have wrought more than 12 billion dollars’ damage in the United States. Of the hardest-hit Caribbean nationsHaiti, Cuba, the Dominican Republic, and Hondurashurricanes have savaged Haiti the worst, killing an estimated 8,400 in this century. In 1963, 5,000 died in Hurricane Flora alone as rain pummeled the island. In August 1980 Haiti was barely spared direct assault by the 170-mph winds of Hurricane Allen, the mightiest Caribbean storm ever recorded. Within days its force was focused on the Gulf Coast of Texas. FOR FIVE YEARS the Atlantic Ocean off the West African coast had been coolpoor nourishment for tropical storms. But temperatures climbed above normal in 1979, and by June 1, when the six-month hurricane season began, the sun had warmed the ocean around the Cape Verde Islands to 80F and more. These waters near the Equator breed most of the hundred disturbances that the National Hurricane Center tracks each year. By late summer, moist air spilling off the African Continent had spawned three tropical storms. The fourthchristened David as it swelledeventually rated a number 4 on the Saffir-Simpson scale. At first David was only a mass of air rising from the sun-warmed ocean. As this air ascended, more flowed in from beneath, then rose, expanded, cooled, and formed rain clouds thousands of feet high. Boosted by earth’s eastward rotation, the clouds spun counterclockwise around a core of low pressure, picking up speed and sucking more moisture into the vortex, like smoke up a chimney. It was Sunday, August 26; David had been born. A day later, winds whirling around the center of the storm reached 74 miles per hour, elevating David to hurricane status. In the next 24 hours wind speed doubled, and David became a superstore that whipped the Atlantic into turmoil over an area 300 miles in diameter. Near the eye, 50-foot waves battered ships at sea.