Lightning See Also: Lightning - Power Line Vulnerability Electrical disCharge accompanied by thunder, commonly occurring during a thunderstorm. The discharge may take place between two parts of the same cloud, between two clouds, or between a cloud and the earth. Lightning may appear as a jagged streak (forked lightning), as a vast flash in the sky (sheet lightning), or, rarely, as a brilliant ball (ball lightning). The electrical nature of lightning was proved by Franklin, Benjamin in his famous kite experiment of 1752. Space probes have photographed lightning on Jupiter and recorded indications of it on Venus, Saturn, Uranus, and Neptune. A single stroke of lightning, which is usually three to four miles long, travels at speeds of up to 100,000 miles per Second. In a single flash, it can carry 100 million Volts of Electricity and reach a Temperature of 55,000 degrees Fahrenheit, five times hotter than the surface of the Sun. Lightning carries enough Energy to Power a 100-Watt Light bulb for as long as three months. Earth is struck by at least 100 flashes every second - more than 8.6 million strikes a day. Lightning strikes have been recorded in every state, sometimes in such huge concentrations that the sky seems to be ablaze. In March, 1991, 15,443 lightning strikes issued during a six-hour period from storms stretching over Iowa, Missouri, Illinois, Wisconsin, Indiana, and Michigan. New York’s Empire State Building is hit by lightning between 23 and 100 Times a year. Central and South Florida are dubbed the lightning capital of the country, because the region’s high humidity and almost daily summer thunderstorms result in two or three times the number of lightning strikes per square mile of any other state. For all its destructive power, lightning has its good side too. Lightning helps to create Ozone, which helps protect the earth from the sun’s harmful rays. Thunderstorms also contribute to the creation of fixed Nitrogen, which falls to the earth in rain and fertilizes plants and soil. Scientists know that most lightning begins with concentrated negative electrical charges - perhaps created by the collisions of rising ice Crystals and falling hailstones - that collect in the lower part of storm clouds at an altitude of some 20,000 feet. The strong negative pull of the lower cloud provokes a reaction of positive charges on the ground below. It’s this clustering of charges that makes your hair stand on end - a sign that lightning may strike near you. Eventually the electrical Force between the charge of the cloud and the ground beneath it becomes too great, and sparks known as stepped leaders overcome the insulating (see Insulation) ability of the Air and shoot earthward. As these leaders approach the ground, the positive charge below sends up sparks of its own called upward streamers. These are more likely to shoot up from the tallest objects - treetops, buildings, summit spires. Where the downward leader and upward streamer meet, the Electric Circuit is closed and the bright flash of lightning, called a return stroke, can be seen. As the air around the return stroke is superHeated, it expands explosively, creating the Shock Waves we know as thunder. Although lightning may appear to shoot down, what you actually see is a pulse of Current rushing up the newly created electrical channel at speeds too fast for the eye to define as upward Motion. A flash of lightning can end after a single return stroke, but more typically it triggers three or four, causing the flickering often seen in lightning storms and horror movies on late-night Television. Lightning Precautions Determine the speed and direction of the storm with the flash to bang method. When you see a lightning flash, count the seconds until you hear the bang of thunder. Divide by five - sound travels about one mile every five seconds - and this will give you an approximation of the storm’s distance from you. Repeating the process will tell you if the storm’s getting closer and how fast it is moving. Pay attention to weather predictions, particularly for the early afternoon and evening when most thunderstorms occur. Have an escape plan for any outdoor activity and be off mountain summits by noon. If you have to make a long boat crossing, be especially watchful. An open canoe is one of the most exposed places to be. To minimize the number of people affected by a strike, don’t cluster in groups. An electrical current can pass from one person to another even if they aren’t touching. And stay away from Metal objects, especially tent poles or fences, since they make good Conductors. When camping, pitch your tent away from likely lightning-strike areas such as near tall, isolated trees. Learn CPR. About 20 percent of lightning victims are killed, and many can be saved by prompt treatment.