Understanding the risks associated with lightning, especially when near or in water, is important for personal safety. Thunderstorms present a serious environmental threat, and knowing how to react can prevent potential harm.
Why Water and Lightning Are a Dangerous Combination
Water acts as an effective conductor of electricity, making it hazardous during a lightning storm. While pure water is a poor conductor, natural bodies of water like lakes, oceans, and even swimming pools contain dissolved impurities such as salts and minerals. These impurities increase the water’s conductivity, allowing electrical current to flow through it.
When lightning strikes water, the electrical current disperses rapidly outward from the point of impact. This creates a dangerous phenomenon known as a voltage gradient. A voltage gradient means that different points in the water will have different electrical potentials, and if a body spans across these points, a current can flow through it. The current can travel significant distances, meaning even a strike far from a swimmer can still pose a threat.
This danger extends beyond natural bodies of water to swimming pools as well. Pool water, often treated with chemicals, also conducts electricity effectively. Furthermore, the plumbing and filtration systems connected to pools can provide a direct path for electrical current to travel from a lightning strike on land into the water. Similarly, lightning striking land near a body of water can create a ground current that propagates through the earth and into the adjacent water, electrifying it.
Staying Safe During a Thunderstorm
Caution is necessary when thunderstorms are present or approaching. The general rule for safety is to immediately seek shelter if you can hear thunder, as this indicates lightning is close enough to strike. This principle, often summarized as “When Thunder Roars, Go Indoors,” applies whether you are in or near water.
If a thunderstorm develops, moving to a substantial building or an enclosed, hard-topped vehicle offers the best protection. These structures provide a safe enclosure, unlike isolated sheds, picnic shelters, or trees, which offer little to no protection from a direct lightning strike or ground current. Open spaces, including beaches and large fields, also increase the risk of being struck.
Even indoor pools can present a risk during a lightning storm due to their connection to outdoor electrical and plumbing systems. It is advisable to exit indoor pools and avoid showering or using other plumbing fixtures when lightning is active nearby. After the last sound of thunder or flash of lightning, waiting at least 30 minutes before resuming any outdoor or water-related activities is recommended to ensure the storm has passed.