It is a common belief that a car’s rubber tires protect occupants from lightning strikes. While a hard-topped, metal-bodied car generally offers safety during a lightning storm, this protection does not come from the tires. The several inches of rubber on a car’s tires are simply not enough to insulate against the immense voltage of a lightning bolt, which can be around 300 million volts. This widespread misconception overlooks the actual scientific principle at play, which makes vehicles a relatively secure refuge during a thunderstorm.
The Real Reason for Safety Inside a Vehicle
The primary reason a car provides protection during a lightning strike is its metal frame, which acts as a “Faraday cage.” This concept, discovered by physicist Michael Faraday, describes an enclosure made of conductive material that shields its interior from electrical fields and currents. This shielding effect is crucial for safety during an electrical discharge like lightning.
When lightning strikes a metal-bodied car, the electric charges within the conducting material redistribute themselves. The car’s metal exterior channels the lightning’s current around the passenger compartment and safely into the ground. This occurs because electricity seeks the path of least resistance. The metal body of the vehicle offers a much easier path for the electrical current than traveling through the air or through the occupants inside.
The electric field inside the conductor becomes zero, effectively protecting anyone inside. This means that even if the car itself sustains damage from the strike, the occupants remain shielded from the electrical current. The lightning strikes the highest points, such as the antenna or roofline, and then travels through the outer metal shell, exiting through the tires’ contact points with the road surface.
Staying Safe in a Vehicle During a Storm
If you find yourself in a vehicle during a lightning storm, remaining inside a hard-topped, metal-bodied car is generally the safest course of action. Keep all windows closed, as an open window can disrupt the protective Faraday cage effect. Avoid touching any metal components within the car, such as door handles, the steering wheel, or electronic devices, as these can conduct electricity if the car is struck.
If possible, pull over to a safe location away from trees, utility poles, or other objects that might attract lightning or fall onto the vehicle. Turn off the engine and hazard lights, then sit with your hands in your lap until the storm passes. Should your car be struck by lightning, wait inside for at least 30 minutes after the last thunderclap before exiting.
After a strike, check for damage to your vehicle, especially the tires and electrical system, before attempting to drive. Convertibles, particularly those with soft tops, and vehicles with fiberglass bodies do not offer the same level of protection. They lack the continuous metal shell necessary for the Faraday cage effect, providing little to no protection from lightning strikes.