There are three different ways that lightning can harm you:
- direct cloud-to-ground strikes
- side flashes
- ground currents
In a cloud-to-ground strike, two arcs of energy meet, an upward leader, emanating from a high point such as a tree or mountain top and one emanating from a cloud. These complete a circuit and create the flash of a direct strike. Direct strikes like this are relatively rare but can cause serious burns and stop the heart.
Side flashes occur when the cloud-to-ground strike fails to meet the upward leader and is attracted to another high point that is more conductive. Side flashes can arc through the air or travel over the ground and carry the same energy as a direct strike. Injuries due to side flashes are much more common than direct strikes.
Ground currents occur once the lightning has hit the ground. From there, it emanates from the point of the strike, dissipating along pathways such as wet rocks, crevasses, and tree root systems. Injuries from this type of lightning strike are also quite common and are just as serious as side flashes and direct cloud-to-ground strikes.
How to Minimize Lightning Risk
To minimize your risk from lightning, you want to get away from tall trees and away from mountain peaks or high ridges. If you are on the water, you want to get to shore and avoid wet areas that can conduct ground current. And if you are in a field, you want to get out of the open to avoid being the high point.
You can further protect yourself by squatting on top of your pack or a sleeping pad or on a boulder that sits on top of other boulders. If you can squat without your hands touching the ground, ground current will travel up one leg and down the other rather than traveling up your torso and cooking your major organ groups.
Lightning is no joke. Check the weather forecast before you hike in the open and make sure you know about possible escape routes, such as side trails, to get below treeline or under the cover of taller vegetation before a thunderstorm starts.