In the aftermath of Hurricane Sandy ‚Äî the largest storm with the lowest barometric pressure ever recorded in the Northern Hemisphere, which devastated the eastern seaboard, leaving 8.2 million people without electricity ‚Äîare the citizens of the U.S. prepared for what‚Äôs ahead?
This has been one of the busiest seasons on record with 19 storms so far being named in 2012, 10 of which have become hurricanes, including Sandy. In 2010 and 2011, we also saw 19 storms; the record was set in 2005 with an astounding 27 storms. The weather is most certainly getting wilder, so let‚Äôs take a much closer look at hurricanes.
Hurricanes are nature‚Äôs fiercest storms, with about 18 occurring each year.
When Bikini Island was demolished with a thermonuclear bomb test, the explosion lifted about five million tons of water into the air. A hurricane over Puerto Rico drenched the island with 1.25 billion tons of water. In 1970, a typhoon (which is the correct name when it occurs in the Pacific) killed one million people in Bangladesh. In 1992, Hurricane Andrew wreaked $30 billion in damage to Florida and left 250,000 people homeless. In 2005, the total property damage from Hurricane Katrina was in excess of $81 billion and over 1,836 people died from flooding. Hurricane Irene caused at least $7.2 billion in horrendous flooding damages.
A hurricane is a huge heat pump that gathers the sun‚Äôs heat from a large area over the ocean and pumps it into a concentrated region. It warms the air, making it rise, sucking in air from the outskirts to fill the void and forcing the entire mass to rotate, counterclockwise, faster and faster. Finally, it collapses in on itself. Hurricanes form only over tropical oceans where water temperatures are at least 77 degrees. They also only occur during the warmest months from June to about November. They pick up not only heat, but also moisture over the ocean.
The normal path of a hurricane is to the west across the Atlantic and then around to the north, as it approaches the continental U.S. For a hurricane to be a threat to Miami it has to start out far to the south below the islands of the West Indies at about seven degrees latitude. They usually do not extend beyond a 30-degree latitude.
The energy release in just one hurricane is as much as in 500,000 atom bombs.
The eye of the hurricane moves very slowly, at about 9 mph, yet its outer wall can have storm-force winds in excess of 186 mph. The average house is built to withstand about 87 mph winds. In the six hours before and six hours after a hurricane hits land it can drop over 14 inches of rain. In addition, the storm surge of waves that can come ashore can be as high as 25 feet (Hurricane Camille, 1969) or a 2.5 story building. In Galveston, Texas one such storm surge hit the coast and killed 8,000 people in 1900.
So what conditions create such violence? First, swirling atmospheric conditions that occur off the coast of east Africa create a moist low-pressure easterly wave. Second, surface winds from the equator are displaced northward (in the Northern Hemisphere) and converge with the easterly wave. Third, when a very high altitude anticyclone (spinning clockwise) sits directly above the center of a low-pressure tropical storm then all of the necessary ingredients are in place to create nature‚Äôs greatest storm. The upper-level high-pressure area in the center pushes the air away, and the low-pressure area at sea level sucks in air and sends it skyward into the center of the anticyclone, which then continues to build up pressure and spin the air away. Warm tropical seawater is evaporated providing energy and the subsequent condensation releases heat into the center of the storm as it feeds upon itself.
The problem facing atmospheric scientists today is that they know how hurricanes move, but they cannot predict with any certainty, even with the most potent super computers, the exact path.
In 1975 the Saffir-Simpson hurricane damage scale, from category one to five, was invented based upon the pressure of the system, its wind speed and storm surge. In 2004, Hurricane Charley was a category four with wind speeds in excess of 130 miles per hour and 15 feet swells. It decimated Florida‚Äôs $9 billion citrus industry and destroyed properties costing approximately $7.5 billion.
Fleets of geosynchronous satellites orbit earth and provide ongoing surveillance over the Atlantic and Gulf of Mexico. They enable scientists to watch the birth and growth of hurricanes from the beginning to the end, just as was the case this week as Hurricane Ivan flattened Grenada. As the hurricanes approach continental U.S., Air Force airplanes fly into the eye of the storm and collect important information. Finally as the hurricane nears land, Doppler radar is used for more exact measurement of the size and swath of the storm. Winds from hurricanes can extend as far as 171 miles in front of the edge.
Once hurricanes move over land, it usually marks the beginning of the end of the eye of the storm because it cuts itself off from the fuel of warm ocean water. If, however, the storm crosses the Florida panhandle and moves back onto the warm water of the Gulf of Mexico it will refuel and continue to be a hurricane.
Hurricanes are powered by the sun‚Äôs energy as absorbed in the surface layer of the ocean and subsequently transferred to the atmosphere by evaporation and condensation of water. One valid concern about global warming is that the oceans will become warmer. And there will be more days of the year when tropical waters are warmer than 77 degrees; these waters will extend farther north.
The hurricane region is predicted to encompass more northern parts of the eastern seaboard as well as the hurricane season being extended. Warmer ocean temperatures will be translated into higher wind velocities and larger storm surges.
Hurricanes are a necessary part of the Earth‚Äôs irrigation system. They bring fresh drinking supplies to much of the American and Asian continents.
Spewing 82 million metric tons of greenhouse gases daily, globally into the atmosphere is causing climate disruption; planning is requisite for tens of millions of people who live along the eastern seaboard and Gulf states as scientists have predicted there will be more intense hurricanes and severe flooding as Earth and its oceans continue to warm and the “new normal” of extreme weather settles in.
Earth Dr. Reese Halter is an award-winning broadcaster, writer and distinguished conservation biologist. His latest books are “The Insatiable Bark Beetle” and “The Incomparable Honeybee.”