When lightning strikes the ground, the discharge occurs in and along the ground surface, not deep into the ground. This creates a dangerous and potentially deadly ground current near the lightning strike. Ground current is responsible for killing many farm animals on a yearly basis and is the cause of most lightning deaths and injuries in the US. The ground current affects a much larger area than the other causes of lightning casualties, and it can travel in garage floors with conductive materials. When lightning strikes an object on the ground, much of the energy travels outward from the strike in and along the ground surface, which is known as the ground current. Anyone outside near a lightning strike is potentially a victim of ground current. In addition, ground current can cause damage to grasses along the path of the lightning current.

When a person is struck directly by lightning, they become a part of the main lightning discharge channel. Most often, direct strikes occur to victims who are in open areas, and they are potentially the most deadly. In most direct strikes, a portion of the current moves along and just over the skin surface, called flashover, and a portion of the current moves through the body, usually through the cardiovascular and/or nervous systems. The heat produced when lightning moves over the skin can produce burns, but the current moving through the body is of greatest concern. The risk of a lightning death or injury increases for a person lying on the ground because the greatest distance between contact points is greater than the distance of the contact points if the person was standing up.

When lightning strikes the ground, it can fuse dirt and clays into silicas, creating a glassy rock called a fulgurite in the shape of a convoluted tube. Fulgurite has been found all over the world but is relatively rare. The shape in the ground is the shape of the path the lightning current followed in the ground. Lightnings electrical jolt may cause the heart to beat more quickly or more slowly than it should, compromising the amount of blood flowing. Lightning can also cause severe burns, shockwaves, and physical trauma, resulting in injuries like internal bleeding, a concussion, a fractured skull, and damage to the spine. Survivors of lightning strikes may suffer from movement disorders and lifelong neurological damage, cataracts, injuries to the ears, and other life-altering ailments.