Why Does the Car Window Keep Fogging Up?
2 Answers
Reasons for car window fogging: 1. The temperature of the car window glass in contact with the outside is relatively low, causing water vapor inside the car to condense on the glass, forming fog. 2. When the window temperature is below the dew point, at a certain air humidity, if the window temperature is lower than the dew point, condensation easily forms on the surface of the window, leading to the common fogging phenomenon on the windshield. 3. There is a certain temperature difference between the two sides of the window. Here are three methods to remove fog from the car window: 1. Use an anti-fog agent: Spray a small amount of defogger on the car window glass and wipe it clean. While polishing the glass, a thin transparent protective film forms on the glass, effectively preventing the condensation of water vapor on the glass and the formation of fog. 2. Utilize air convection: Due to seasonal changes, the temperature difference between the inside and outside of the car increases. The warm and humid air inside the car meets the cold windshield, releasing heat and liquefying, which easily causes fogging. Therefore, you can also slightly open the car window to allow air convection between the inside and outside of the car, balancing the temperature difference and achieving an anti-fog effect. 3. Use the car heater: Turn on the heater and direct warm air onto the glass to quickly raise the temperature of the front glass, eliminating the conditions for the warm and humid air inside the car to release heat and liquefy on the window glass, thereby preventing fogging.
I've been driving for over twenty years, and the constant fogging up of car windows is particularly annoying, especially during seasonal changes or rainy days. The main reason is the significant temperature difference between the inside and outside of the car. In summer, the cold air from the AC chills the glass, causing hot interior air to condense upon contact; in winter, the opposite happens with heating. High humidity exacerbates the issue, such as when passengers' breath accumulates moisture. The solution is simple: first, turn on the external air circulation to ventilate and reduce humidity; while driving, use the defogging button on the AC, set the fan to maximum, and direct it at the windshield—the fog will clear within a minute. You can also apply an anti-fog coating to clean the glass in advance as a preventive measure, as thick oil films can absorb moisture. Safety comes first—when fog obstructs visibility, I've made it a habit to adjust the AC immediately upon starting the car and to be extra cautious in rainy weather to avoid sudden braking. Regularly check the AC system; a clogged filter can slow down defogging, so ensure the heating and cooling functions work properly. Remember these tips, and fogging won't be a big issue—safe driving is what matters most.
