An electromagnetic pulse (EMP) is a short burst of electromagnetic energy interference caused by an abrupt and rapid acceleration of charged particles, which can damage electronic components by short-circuiting them. An EMP can contain many energy components of the electromagnetic spectrum, from the very low frequency waves to the ultraviolet wavelengths. One very common cause of EMPs are lightning strikes, which supercharge ions in the atmosphere and cause electricity in the power lines to surge.
For example, a large solar flare striking the earth would cause an EMP.
An EMP used as an act of war is when a nuclear device is detonated several hundred miles up in the atmosphere to intentionally disable a large area’s electronics. That single detonation could bring any country to its knees!
In any event, if you see one of these things,
don’t worry… it’s too late.