What Causes Fogging on Car Windows on Rainy Days?
2 Answers
The reason for fogging on car windows during rainy days is: there is a temperature difference between the inside and outside of the car, with the interior temperature being higher than the exterior, causing water molecules in the air inside the car to condense into mist when encountering the cold surface. More detailed information is as follows: 1. Firstly, the reason for fogging on rainy days is due to high air humidity and a significant temperature difference between the inside and outside of the glass, causing water vapor to condense on the front windshield. Therefore, if the vehicle is equipped with a manual air conditioning system, you can turn on the front window defogging mode, set the fan speed to maximum, turn on the A/C switch, and then adjust the temperature to the lowest setting. The fog on the glass will disappear shortly. 2. If the vehicle is equipped with automatic air conditioning, generally, you only need to press the one-touch defrost button, and the fog will be eliminated quickly. If the ambient temperature is too cold for the air conditioning, you can also turn on the warm air, set the air volume to maximum, and then activate the front window defogging mode. The fog will disappear within minutes. 3. Usually, the rear windshield is equipped with electric heating, so you can directly turn on the rear windshield heating, and the fog will be quickly eliminated. Many rearview mirrors also have heating functions. You can apply some soapy water or detergent on the windshield in advance to prevent fogging. Of course, the best option is to spray a specialized glass anti-fog product for better results.
I have a lot to say about foggy car windows on rainy days. It's mainly due to the temperature difference between inside and outside: the car is much warmer than the outside, and the moisture from breathing plus the dampness on clothes immediately condenses into tiny water droplets when it hits the cold glass. The windshield is especially prone to fogging because of its large surface area and lower temperature. When using the air conditioning to defog, it's best to turn on the external air circulation at the same time to quickly expel the moisture. If you find that turning on the internal air circulation alone makes the fogging worse, it means there's too much moisture inside the car. Keeping a defogging spray handy is quite effective; spraying it once a month can maintain the effect. By the way, in winter, remember to wait until the engine warms up before turning on the hot air to defog, otherwise the glass may become blurry.
