Five Hazards To Safe Flight

The old saying that "lightning never strikes twice in the same place" may be somewhat of a comfort to people suffering from keraunophobia – the fear of lightning. But there is no truth to the adage—in fact, the exact opposite is actually the case. Experience has shown that if lightning strikes something once this is a pretty good sign it has found an attraction and will return. The Empire State Building, for example, is, favorite lightning hunting ground for scientists because of the frequency with which lightning strokes have connected with the 1,250-foot-tall structure. During a three-year period the tower was struck sixty-three times, and during one severe storm it was hit fifteen times in fifteen minutes. The steel framework of the building conducts the bolts harmlessly to the ground, while the structure protects an area roughly as far from the base of the building as the tower is tall. Because of the frequency with which lightning is known to strike the Empire State Building, special recording machines and high speed cameras have been focused on it by scientists interested in learning more about this spectacular phenomenon. The cameras were not located on the building itself, hut were set up approximately 2,400 feet away, with an unobstructed view of the building.

Some surprising things were revealed by these photographs surprising, at any rate, to people who are not electrical experts. A lightning stroke is not necessarily one single streak of current. It may consist of as many as forty discharges or multiple strokes—this is the reason some lightning flashes seem to flicker when viewed by the naked eye. The bolt originates as a comparatively weak "leader stroke," which progresses in a series of steps towards the earth, and, when contact is made, a heavier mail stroke surges upward from earth to cloud. Lightning is a fearfully destructive force, but fortunately the effects of a single bolt are not usually widespread. Examples of its power at point of contact, if not evident enough in riven trees, fused metal and blasted buildings, can be seen in the fulgurites or "lightning tubes" sometimes found where lightning charge enters the earth.

Airplane pilots, who venture directly into the realm of thunderclouds and storms, are always warned to avoid the anvil-shaped cumulonimbus clouds that mean thunderstorms. Five hazards to safe flight—hail, lightning, turbulence, icing and squall winds—are to be found in thunderstorms. Our larger planes can and have survived all these hazards. Metal planes may be struck by lightning and the passengers feel no marked effects, but pilots of wood or fabric planes are advised to give thunderstorms a wide berth.

By: davidbunch

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