Responding to disaster |

Responding to disaster

Breathe out on a cold winter’s day. Water vapor in your breath condenses to form droplets: a cloud.

Cloud droplets are tiny, millions of times smaller than raindrops.

Sweat evaporates and cools us off – evaporation absorbs energy.

Condensation is the flip side of evaporation.

Condensation releases energy and heats things up.

The air over the tropics and over the Gulf of Mexico contains tremendous amounts of water vapor. When it condenses into cloud droplets, it releases tremendous amounts of heat.

Warm air, heated by condensation, rises from the tropics, flows north and sinks over the poles. But, like a freeway at rush hour, the system sometimes overloads. Massive upwellings of warm, moist air may spin up to become tropical storms and, when really overloaded, hurricanes.

One of the legacies of the invention of nuclear weapons has been the need for a new unit of energy: the ton, usually expressed as kilotons, or megatons – the energy released by the explosion of tons, or thousands or millions of tons, of TNT.

Actual use of the atomic bomb led to another, related unit – the Hiroshima bomb, equivalent to 15,000 tons of TNT.

The power of an average hurricane – the energy released by forming cloud droplets – is equivalent to detonating 10 Hiroshima bombs every second.

Hurricane Katrina was much larger than the average hurricane. Fortunately, nearly all of a hurricane’s energy is expended in pushing air upward to where it can flow toward the poles. Maybe a quarter of a percent is converted to winds.

Nature tends to create with curves, humans with straight lines. Coastal Louisiana is laced with bayous – slow streams carving lazy curves as they make their way to the Gulf. South of the town of Houma (“HOME-uh”), however, the Houma Ship Channel runs straight to the Gulf.

Where air rises, it presses less hard on whatever’s below. When Katrina hit the Louisiana coast, the storm’s low pressure allowed the waters of the Gulf to rise. With the straight shot provided by the ship channel, propelled by the hurricane’s winds, Gulf waters surged miles inland.

Metal and glass and glazed ceramic don’t absorb water, but nearly everything else in a house does: wallboard and flooring; clothes (still in the dryer) and food (still in the pantry); insulation and bedding; computers and stereos and cameras and televisions. Soaked for days or weeks, what wasn’t lost to water was quickly lost to mold.

Early last month, I joined a group organized by the American Friends Service Committee to help people in Louisiana’s bayou country put their homes and lives back together. We pulled nails to raze one home, pounded nails to raise another.

We helped people understand they were not alone.

We spent time in New Orleans, too. Tens of thousands of homes, hundreds of thousands of cars had been destroyed by saltwater. Standing on the levees, I looked down on concrete slabs – all that remained of homes washed away by the wall of water released when the flood walls broke.

The devastation extended, not block after block, but mile after mile. Each house bore a spray-painted “X,” whose four quadrants bore symbols to indicate when the house had been inspected, by whom, and the number of human corpses found within.

The cleanup of the Gulf Coast – not the rebuilding, but the cleanup – will take years. New Orleans has been de-populated – four-fifths of the city is gone.

On the scale of the hurricane, our AFSC project was a drop in the bucket. For the families we helped, it was more. As important as our construction work was, we showed them they were not alone.


Alan Stahler trained as a biologist and is an amateur astronomer. He teaches private enrichment classes for students of all ages. His science programs can be heard at noon on alternate Tuesdays on KVMR-FM (89.5).

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