Though city dwellers have relatively little to fear from lightning (nearby tall buildings have steel frames that are well grounded), homeowners in rural and suburban areas will do well to acquaint themselves with how lightning works and with the protective steps that can be taken to avoid damage to lives and property. Nothing can be done about preventing lightning, but there are ways of controlling it. Among these is the installation of a decently grounded system of UL (Underwriters' Laboratories) sanctioned lightning rods.
To understand how these work, the homeowner should understand first why a lightning flash happens. When storm cloudsform, weather condition sometimes cause great amounts of electrical charges to gather—all positive or all negative. When these charges develop, they cause an equal amount of opposite charges to build up in the earth's surface directly below.
Because opposite electrical charges have an excellent attraction for one another, the ground charges tend to flow upwards into the tallest structuresin a feat to get closer to the clouds. At the same time, the countless of air-borne charges tend to reach downward to their earth-borne opposites. The potential between the two builds up, till a point is reached when they eventually leap across the barrier of air between them. This discharges enormous energy (comprising of millions of volts and thousands of amperes) in a tiny thousandth of a second and often induces nearby air molecules to literally heat up and explode—thus creating the powerful clap of thunder which comes with most lightning strokes.
The bolt has exhausted its energy when the air-borne charges have found their way into the ground below. Damage to trees, buildings or other structures is made by the resistance offered to the path of this large spark as it searches its way down to a damp spot on the ground.