How to Remove Fog from Car Windows When It Rains Outside?
2 Answers
When it rains outside, the methods to remove fog from car windows are: 1. Air Conditioning Cooling Method, using the car air conditioner's cooling and dehumidification function to reduce air humidity and remove fog; 2. Air Conditioning Heating Method, using the car air conditioner to reduce the temperature difference and remove fog. There are two conditions for car window fogging when it rains: one is high humidity, and the other is low temperature. Under certain air humidity conditions, when the window temperature is lower than the dew point temperature, condensation forms on the window surface, which is the fogging phenomenon we often see on the windshield. Additionally, when there is a certain temperature difference on both sides of the window, and the saturated vapor pressure on the lower temperature surface is lower than the surrounding environment's vapor pressure, moisture gathers on the glass surface and forms tiny water droplets, creating fog. If the dew point temperature is above zero degrees Celsius, fogging occurs; if it is below zero degrees Celsius, frost forms.
As an experienced driver, when encountering foggy windows on rainy days, my first choice is to turn on the air conditioning defogging mode and directly blow cold air onto the windshield. This can clear the fog within seconds because cold air quickly reduces the temperature difference. If the fog is particularly heavy, I slightly roll down the window for ventilation to reduce moisture accumulation inside the car, while using a clean towel to wipe off residual water droplets to avoid obstructing the view. For prevention, I regularly clean the glass because dust and oil films can worsen fogging issues. After washing the car, I also apply a layer of anti-fog agent to prevent water droplets from adhering easily, saving me the hassle every time it rains. Remember, visibility is already low in the rain, so don’t rush to drive fast if fog appears—safely pull over to handle it first. Following these practices long-term also saves unnecessary expenses on car glass maintenance.
