Direct Hit: Lightning current may enter the body at the head and passing through the body, be discharged to the ground generally through the feet. If several people are standing close together, they may all be struck.
Contact Voltage: If we visualize a person touching a tree which is struck by lightning, a potential difference, u , is developed along his body between the highest point at which he touches the tree and the earth.
Side Flash: When a tree is struck by lightning, the resistance along the tree between the ground and the top of a sheltering person is of the order of a few kilo-ohms, while the person is essentially at earth potential. As the lightning current passing down the tree increases in magnitude, the potential difference between the ground and that part of the tree level with the person's head, might become greater than the electrical breakdown strength of the air gap between that part of the tree trunk and the person's head.
Step Voltage: When lightning strikes open ground, the current
is discharged into the mass of the earth. On uniform ground, the discharge
takes place in a regular pattern, although it might appear quite irregular
if the ground is non-uniform. In humans, this potential will cause a current
to flow through the legs and the lower trunk, However, little, if any currents
flow through either the heart or brain, therefore death is very rare.
