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flows perpendicular to the lines of equal potential. These lines and their distribution are shown in the figure. The closer the potential lines are together, the greater is the current flow. Near the summit the lines are very close together, while near the base, they are relatively far apart; the ground currents are strong near the top and weak near the base. Also, the lines are close together on vertical walls, while on the horizontal ledge they are far apart. Similarly, it is found that the current flow is greater on the face of a mountain than on its ridges. The two types of danger from lightning consist in a direct strike and in a subsidiary danger from the ground currents. Anywhere but on the summit or very near to it the chance of being the victim of a direct bolt is small and the probability of being killed is almost certain. In contrast, the chance of meeting ground currents is almost certain, while with a few precautions the probability of being injured by the currents is small. |
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