Return to Do giraffes make good targets for lightning? (idea)

Giraffes and other ungulates usually succumb to lightning strikes because of a phenomenon known as "step potential". A nearby strike raises the ground's electric potential at the point of strike, while some distance away the potential is normal. This creates a potential gradient between the strike point and the areas with normal potential that surround the strike point. If an animal, or human, is standing nearby with one foot closer to the strike centre, this foot will be at a higher potential than the other foot. This potential difference causes current to flow between the two legs, which can stop the heart.

Ungulates, having a greater distance between their feet, are subject to a higher step potential and thus a higher current flow. Even worse, during storms animals tend to huddle together, which creates even longer step potential loops. In such circumstances, one strike can kill many animals. This happened to a small group of elephants in the Kruger National Park in South Africa, where seven were killed at once in a single strike. The dramatic effect of step potential loops has given rise to the myth that animals tend to attract lightning, which is patently untrue.

The problem of step potential is also why the recommended safe position to adopt during lightning storms is to crouch down with your feet together to reduce the magnitude of the step potential.

Owing to the random nature of lightning strikes, it is unlikely that lying down offers any protection. Certainly, sheltering in a group offers no protection to either animals or humans--in fact it will actually increase the danger because of the step potential phenomenon.

Giraffes are good targets, but there are not many of them and their remains are often quickly consumed by scavengers, destroying evidence of the strike. Even in the Bushveld, a low-lying area where thunderstorms are common, lightning is not a leading cause of giraffe death. There seems to have been no evolutionary selection for specific avoidance behaviour--cowering giraffes are not a sensitive predictor of thunderstorms.

Source: NewScientist - the last word

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