Books > Lightning: Fire from the Sky

LIGHTNING: FIRE FROM THE SKY (EXCERPT)
Somewhere in central Florida, a kingfisher dives from the top of a dead tree into a pond, and emerges with a minnow. Back on its perch, it tilts its head and swallows the fish, then fluffs its feathers to cool in the 95-degree heat. Above, a column of warm air slowly pushes its way into the atmosphere. Heated by the midsummer sun, and laden with moisture that has evaporated from swamplands and golf courses, this juggernaut weighing 10 million tons rises one mile, and then two, into the clear Florida sky. As it climbs, it creates a virtual chimney, sucking more warm air with it. Two miles up, the temperature drops to around 45 degrees, and now, gathering mass and speed, the huge column of moist air pushes into the upper atmosphere. At five miles up, the temperature is well below freezing. Some of the water vapor condenses into microscopic drops of water and becomes ice crystals.

Far below, a golfer eyes the sky. The first large drops of rain have fallen. As the cloud above him continues to build into the ominous form of a thunderhead, parts of it are actually rising faster than the rain drops can fall, and as a result, some of them are stripped of some of their moisture. The violent forces and friction leave parts of the cloud with a positive electrical charge, and other parts with a negative charge. Charge accumulates until the voltage is so high—a difference in potential of millions of volts—that the electrical resistance of the air is broken down, and a path of ionized air is created. Ionized air readily conducts electricity, acting as if a copper wire was dropped through the cloud. The massive amount of electrical energy stored in the cloud flows down this invisible conductor. In a fraction of a second, the huge electrical current raises the temperature tens of thousands of degrees, vaporizing the air and water, fusing oxygen and nitrogen and producing multiple rapid flashes of light. The process within the ionized air is so violent that the vaporized gases are blown away from the current’s path at supersonic speeds, causing a loud crash of thunder as the sound barrier is broken. Below the storm, the kingfisher seeks a sheltered perch. The golfer sees the lightning flash and 20 seconds later hears the peal of thunder. From this he knows that the strike was only four miles away—time to hurry to the clubhouse and call it a day. He knows what lighting can do to a man holding a metal golf club.