When lightning strikes a lake, powerful electrical currents spread through the water. This can have various effects on aquatic life, particularly fish.
Fishing has long been a popular recreational activity, attracting not only fishing enthusiasts but also celebrities. However, for those who love outdoor activities, one unavoidable question is : What happens if lightning strikes a lake while we are there? And for fish—creatures that spend their entire lives underwater—how serious is this threat?
Are aquatic creatures in danger if lightning strikes a lake?
The skin effect is an important physical phenomenon in the field of electromagnetism, especially in high-frequency power transmission systems. Simply put, when alternating current flows through a conductor, the current tends to concentrate in the outer layer of the conductor rather than being evenly distributed across its cross-section.
Contrary to the typical portrayal in cartoons, when lightning strikes a body of water, it does not instantly kill all living creatures in the lake. Instead, the current primarily travels along the surface of the water rather than penetrating deeply. This phenomenon is known as “Skin effect.” It is similar to how electricity travels on the surface of cars or other conductive materials when struck by lightning. The current will run along the surface rather than passing through the entire object.
The skin effect is a fundamental principle behind Faraday cages, enclosures designed to protect structures inside from electrical currents. This phenomenon is also observed in humans when struck by lightning, referred to as “flashover,” which can cause surface burns with complex patterns known as Lichtenberg figures.
A Faraday cage is a device created from a conductive material that encloses objects, effectively blocking external electromagnetic fields from affecting the interior. It acts as an “electrical shield,” protecting devices or individuals inside from external electric and magnetic fields.
When lightning strikes a lake or ocean, the current primarily affects creatures near the surface. However, the penetration depth of lightning into the water can vary, and much remains unknown about the exact depths that each lightning strike can reach. Therefore, do not rely solely on the diving ability of each fish species to avoid being struck by lightning while swimming during a storm.
Although the temperature of lightning can reach 27,760 degrees Celsius (approximately 50,000 degrees Fahrenheit), nearly five times hotter than the surface of the Sun, water has excellent heat dissipation properties, significantly reducing the temperature of lightning upon contact with the water surface. This means that water will not start boiling when struck by lightning, contrary to what many cartoons often portray.
Fish swimming near the surface or directly in the strike zone are highly likely to be electrocuted and die instantly. However, fish deeper underwater are generally safer as the current primarily concentrates at the surface. Still, if the lake is not very deep or the lightning strike is very strong, the current can extend deeper and cause harm.
While fish may be protected by the skin effect, humans do not have the same luck. If a person is swimming or fishing on the surface when lightning strikes, they can face significant danger. The electrical current from lightning can spread from 10 to 100 meters or more, depending on the intensity of the strike. This means that you do not necessarily have to be right next to where lightning strikes to be affected by its energy—which can reach up to 10 million volts.
The electrical current from lightning can spread from 10 to 100 meters or more.
Lightning strikes can cause a sudden increase in water temperature at the point of contact, creating thermal shock for fish and leading to their death. The shock waves from a lightning strike can also damage the internal organs of fish, particularly larger species.
To ensure safety during storms, a commonly recommended guideline is the “30/30 rule.” According to this rule, when you see the first flash of lightning, if the accompanying thunder is heard within 30 seconds or less, it means the storm is close enough to pose a danger. The closer the thunder sounds, the nearer the storm is. It is also advised to wait at least 30 minutes after seeing the last flash of lightning before returning to the water.
This guideline is based on the speed of sound and light. Sound travels at a speed of 343 meters per second (about 1 mile in 5 seconds), while light travels at about 300,000 kilometers per second. By counting the seconds between the flash and the thunder, and then dividing by three, you can estimate the distance of the storm in kilometers; divide by five for the distance in miles.
Lightning poses a threat not only to fish but also significant danger to humans.
A lightning strike on a body of water can have serious consequences for aquatic life, but not all fish die. The survival of fish depends on various factors.
Ultimately, the best and safest way to avoid being struck by lightning while in the water is not to swim or fish when there are signs of an approaching storm. Whether you are a fishing enthusiast or just looking to relax by the lake, safety should always come first. Lightning is not only a threat to fish but also poses significant danger to humans, especially when we are immersed in nature.
