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Taming the Tempest Some celebrities achieve such fame that they are known by a single name—Elvis, Oprah—and that name will forever be at- tached to them and requires no explanation. Katrina is such a name. In late August 2005, an African tropical wave moved across the Atlantic, intensified to a hurricane, and made landfall in Florida. This hurricane, named Katrina according to an alphabetical system, sidled away and regained power, more than doubling in size to strike again, then again, and again, along much of the Gulf Coast. The hur- ricane produced 175-miles-per-hour winds, spawned 143 tornadoes, caused 1,836 human deaths (more than 700 are still missing), and ultimately amassed $110 billion in damage. Seven years later, swaths of land remain unusable due to catastrophic damage and pollution, and regional economies have not recovered. Normally, hurricane names are reused by the naming organization, but Ka- trina’s name has been stricken from the list, and the name has plummeted in popularity among baby names. And she wasn’t even the deadliest: 8,000 people died in 1900 when a hurricane struck Texas. Fortunately for baby name books, that storm went unnamed. Although predictions about a hurricane’s path have improved substantially in recent years, forecasting its strength is difficult be- cause of unknowns concealed in the depths of the storm. Now Los Alamos atmospheric scientist Jon Reisner and his team are using lightning as a predictor of a storm’s strength. Lightning does not accompany all tropical storms, but during the record-setting hur- ricane season of 2005, three of the most powerful storms—Rita, Katrina, and Emily— did have lightning and lots of it. According to NASA, hurricanes are most likely to produce lightning when they’re making landfall. In broad terms, lightning activity within and surrounding a hurricane has been known to indicate when and where a hurricane may intensify. Research also shows that if the electricity moves from the eye (or center) to the periphery of the cloud, the energy is prob- ably dissipating. Los Alamos researchers are trying to flesh out that connection between More than 1.2 million people along the northern Gulf coast were ordered to evacuate to escape Hurricane Katrina’s floodwaters in 2005, and this New Orleans neighborhood is still devastated. Reisner’s research may help citizens prepare for such hurricane emergencies. 20 1663 los alamos science and technology magazine june 2012 In this simulation of Hurricane Rita, red dots denote areas of active lightning within cloud regions, which correlate well with observed lightning locations during a period of rapid storm intensification. lightning activity and hurricane intensity. Lightning produces electromagnetic waves with high and low frequencies during a strike. Los Alamos sensors detect these frequencies, allowing researchers to charac- terize the charge associated with the flash. The detectors and instruments are mounted aboard planes and flown into the hurricane’s eye. Reisner brings the lightning data into a simulation—the first to incorporate a three- dimensional model of the lightning activity in the hurricane. Reisner also discovered that by looking at individual water particles, he was able to construct a more realistic representation of the cloud structure within a hurricane. Traditional hurricane models, his team found, improperly express cloud boundaries, struc- turing clouds as continuous objects rather than collections of particles. When a storm develops as warm ocean water evaporates, winds force humid air to rise until the vapor condenses back into tiny liquid particles. During condensation, energetic water particles release heat as they collide and condense, fueling the storm and forming the hurricane’s eye wall. These particles interact or change at miniscule scales—between