Isaac's Storm - Erik Larson [50]
The eyewall is an impossibly hostile realm where air flowing toward the center reaches its highest velocity. Observers trapped in a cyclone’s eye consistently reported hearing a great roar as the calm passed and the opposite eyewall approached. The frightened Malay crew of a ship off Sumatra called this chorus the Devil’s Voice. To Gilbert McQueen, commanding a ship bound for London, the eyewall sang its advance in “numberless voices, elevated to the highest tone of screaming.”
One of the strangest encounters with the eye was that of Capt. William Seymour, of Cork, Ireland, and his brigantine Judith and Esther, as the ship made for Jamaica in the summer of 1837. Seymour sailed into one of four hurricanes that scoured the Caribbean that summer within days of each other.
The storm knocked the ship onto her side three times, the third time just as the ship was leaving the eye. Once again the ship righted, but now something profoundly peculiar occurred that piqued great excitement among seekers of the Law of Storms. Lt. Col. William Reid wrote at once for more details.
Captain Seymour replied: “For nearly an hour we could not observe each other, or anything but merely the light; and most astonishing, every one of our finger-nails turned quite black, and remained so nearly five weeks afterwards.” He could not explain it. “Whether it was from the firm grasp we had on the rigging or rails I cannot tell, but my opinion is, that the whole was caused by an electric body in the element. Every one of the crew were affected in the same way.”
Such phenomena, however, were only sideshows to the most important feature of the eye, its plummeting pressure. Normal pressure at sea level is 29.92126 inches, or 14.6969 pounds per square inch. In the wall of the eye, spiraling and ascending winds lift air at over a million tons per second. As the air soars, pressure at the surface falls. Air within the eyewall rises with so much force it literally lifts the surface of the sea, one foot for each one inch of barometric decline. The lowest barometric reading ever recorded was 26.22 inches, during Hurricane Gilbert in 1988. Gilbert raised the level of the sea by over three feet.
Doctors have long been tantalized by persistent anecdotal evidence that a sudden, severe drop in atmospheric pressure can trigger premature labor and cause aneurysms to burst. Seismologists have wondered whether such a decline could rupture an already-fragile fault. Early observers of hurricanes often claimed that earthquakes acccompanied the worst storms, but William Redfield and Lieutenant Colonel Reid debunked their accounts, attributing the tremors to the interplay of thunder, wind, and imagination. One later incident, however, has resisted explanation. On September 1, 1923, a severe typhoon struck Japan, coming ashore first at Yokohama, then moving to Tokyo. As the storm raged, an intense earthquake occurred. The quake crumpled buildings and set fires; the typhoon whipped the fires into a firestorm. A Weather Bureau meteorologist, C. F. Brooks, argued that low pressure and high water, acting in concert, might have caused the earthquake. He calculated that a two-inch drop in pressure lessened the load on a single square mile of land by roughly two million tons. At the same time, a ten-foot increase in the depth of the sea caused by the wind pushing water toward shore increased the load by about nine million tons. The sudden differential, he argued, might have been enough to fracture a fault line already stressed to its limits.
The storm and earthquake together killed 99,330 people. Another 43,500 simply disappeared.
No one in Isaac’s time would have believed such low pressures could occur. Until September 1900, any measurement under 29 inches was considered an error until proved otherwise.