Why is there water mist inside the car headlights?

[JulianFitz]

Water mist inside the car headlights is caused by water ingress. Here is relevant information about car headlights: 1. Incandescent lamp: The bold idea of a physics professor occurred in 1802 at the St. Petersburg Surgical Medical Institute in Russia, where a physics professor named Petrov announced his intention to "obtain light from electricity." In the early 19th century, when bonfires, torches, animal and vegetable oils, and gas were still the main lighting methods, and electricity was still a novelty, this decision was nothing short of a fantasy. 2. Arc lamp incandescent lamp: Around the same time, in 1809, the famous British chemist Davy, who was engrossed in electrochemical research, also discovered the electric arc. He personally made a large capacitor, used 2000 vodka batteries, and obtained a more intense and brighter arc light.