Why is there fog on the inside of car windows?

[VanTeagan]

Here are the reasons for fog forming on the inside of car windows: 1. When the window temperature falls below the dew point under certain air humidity conditions, condensation forms on the window surface, causing windshield fogging. 2. When there's a temperature difference between both sides of the window, and the water vapor saturation pressure on the colder surface is lower than the surrounding environment's vapor pressure, moisture gathers on the glass surface and forms tiny droplets, creating fog. Here are extended methods to prevent window fogging: 1. Anti-fog spray method: Spray a small amount of defogger on car windows and wipe clean. This not only removes dirt and stains but also forms a thin transparent protective film that effectively prevents moisture condensation. 2. Air conditioning cooling method: Use the AC's dehumidification function to reduce air humidity. If humidity is excessive and AC effects are insufficient, slightly open a window to quickly reduce cabin humidity. 3. Air conditioning heating method: In winter, direct warm air onto the windshield to rapidly increase its temperature and reduce the temperature difference between inner and outer surfaces, preventing excessive windshield fogging.