Are Lightning Strikes Magnetic?

There’s a reason why metal attracts lightning better than other materials: Electrical currents cause magnetic fields to form around them. Lightning strikes are rapidly moving electric currents and the movement of electric charges produces a magnetic field. This is called electromagnetism. The electromagnetic properties of lightning are apparent in several ways. The two most apparent magnetic properties of lightning, however, are remanent magnetization and electromagnetic pulses.

Remanent Magnetization

One way lightning demonstrates magnetic properties is by creating magnets. Soil, rocks, and metal materials become magnetized when struck by lightning. In fact, some theories suggest lightning is responsible for the Earth’s supply of lodestone, a naturally-occurring magnetic rock. Lightning-induced remanent magnetization (LIRM) is the magnetic mark left on materials after they were struck by lightning. People who study the history of magnetism on Earth or paleomagnetics have trouble mapping the natural changes in Earth’s magnetic field if a location has experienced lightning strikes that altered the magnetic signature. The magnetism of lightning also allows researchers to measure the electrical current of a lightning strike. According to Ampere’s Law, the magnetic field caused by an electrical current is proportional to its source. Therefore, you can use magnetic links to measure lightning currents. Usually, currents are 5,000 to 20,000 amps but currents over 200,000 amps have been reported.

Electromagnetic Pulse (EMP)

Lightning can also cause an electromagnetic pulse (EMP). When lightning supercharges ions in the atmosphere, it can cause a brief, but powerful electromagnetic pulse. EMPs weaken as they move away from their source. But if they pass through conductive materials such as electrical wires or power lines the EMP will cause a surge. A power surge caused by lightning can damage electronics or cause a power outage. For example, people often buy surge protectors to prevent damage from EMPs. As everything becomes digital and we increasingly rely on electronics in our lives, many people see electromagnetic pulses as a serious potential threat. But there are also ways of harnessing the power of an electromagnetic pulse to use for our own purposes. How can we use electromagnetic pulses to help us in the future? Image by David Selby