National Geographic : 2004 Apr
the Geyers-Hayley and Heather, nicknamed "Twister" and "Stormy" by the local media. Rex struggles with insurance claims and leans on his extended family for help. The Manchester storm yields some of the most startling measurements ever obtained. One probe registers a drop in barometric pressure of 100 millibars, an astounding measurement that verifies theoretical calculations. Computer mod els predict that pressure drop is an indicator of wind speed inside the tornado, so this read ing will help solve one of the great unknowns: How fast are the winds in the core of a tornado? "Tim's measurements are some of the best ever made," says Rasmussen. "He's the first to measure everything-temperature, humidity, wind speed and direction of a tornado. The data collected will be a gold mine." Sometimes you get the bear. WEBSITE EXCLUSIVE See video footage shot in the shadow of a tornado, and hear storm chaser Tim Samaras and photographer Carsten Peter describe the thrill and terror of that close encounter at natlonalgeographic.com/magazine/0404.