How a strike reaches beyond its target
Lightning does not vanish when it hits a tree, pole, or patch of ground. The electrical charge spreads outward from the strike point through whatever paths are available. In soil, some current can move across the surface and through the ground. A person nearby may be injured when current enters one part of the body and leaves another.
The risk can be especially high when a person’s feet are far apart. The ground under one foot may be at a different electrical potential—a measure of electrical energy—than the ground under the other. Current can then pass up one leg and down the other. This is called step voltage. Keeping the feet close together reduces the difference between the two contact points, though it does not make an exposed location safe.
Why nearby objects matter
A strike can also jump from a tall object to a person standing close to it. This is known as a side flash: current travels through the object, then crosses an air gap to a nearby person or another conductive path. Metal fencing, wet surfaces, and connected structures can help carry current, but lightning can also cross gaps without a metal link.
That is why shelter is more than an overhead cover. An umbrella may intercept rain, but it does not isolate someone from current moving through the ground or jumping from a struck object. A substantial enclosed building or a hard-topped vehicle offers much better protection because its structure provides a safer route for the electrical charge around the occupants. The important distance is not only between a person and the storm above, but also between that person and the strike’s paths through the surroundings.
