What to Do When the Car Windshield Fogs Up on Rainy Days?

[VanAndres]

Press the defogging button, turn on the air conditioning cooling (A/C) switch, set the temperature to the lowest, and turn on the external circulation to defog. Both cold and warm air can be used to defog the car windows, but warm air is slower than cold air. The most effective method is to use cold air, which blows dry cold air directly onto the glass, preventing water vapor from condensing on the glass and achieving the purpose of defogging. The method of using warm air to defog is the same as using cold air, but it should be noted that warm air should not be used for defogging on rainy days, as it will initially increase fogging. When the car windows fog up, the external circulation should be turned on. The reason for car window fogging: There is a certain temperature difference between the inside and outside of the car. If the temperatures inside and outside the car are different, the surface of the side with the lower temperature will have a saturated vapor pressure lower than the surrounding environment's vapor pressure, causing water vapor to gather on the glass surface and form tiny droplets, resulting in fogging. Methods to defog car windows: Air Conditioning Cooling: Use the air conditioning's dehumidification function to reduce air humidity and remove fog. In summer, especially when multiple people enter the car and the air conditioning is not turned on in time, the humidity of the exhaled air is high, and the windshield will quickly fog up. At this time, you can turn on the air conditioning to blow cold air onto the windshield and use the dehumidification function to quickly remove the fog. However, if the humidity is too high and the air conditioning is not effective, you can slightly open the window to quickly reduce the humidity inside the car. Of course, it can also be used in combination with the air conditioning for faster results. Air Conditioning Warm Air: Use the method of reducing the temperature difference to remove fog. In winter, use warm air to blow hot air onto the glass, quickly raising the temperature of the windshield and reducing the temperature difference between the inside and outside surfaces of the window, which can prevent excessive fogging on the windshield. However, it should be noted that the rear and side windows heat up slowly, so it takes longer to completely remove the fog. Whether the air conditioning is automatic or manual, turning it on helps with dehumidification; the temperature control should not be set to the coldest position, otherwise, the outer surface of the windshield may fog up over time. Spraying Anti-Fog Agents for Prevention: Spray a small amount of defogging agent on the car windows and wipe it clean to remove dirt and stains from the glass. While polishing the glass, a thin transparent protective film is formed on the glass, which effectively prevents water vapor from condensing and forming fog, especially suitable for cold winters. Alternatives to anti-fog agents include dish soap, soapy water, glycerin, alcohol, or salt water. After drying, use a chamois or soft dry cloth to wipe off excess fibers, which can keep the car windows fog-free for several days. Opening Windows for Airflow: If the fog inside the car is not heavy, you can open the windows on both sides to create airflow between the inside and outside of the car, reducing the temperature difference and allowing the fog to slowly disappear. The principle of this method is the same as using cold air from the air conditioning. The downside of opening windows for airflow is very obvious: it cannot be used during rain or snow, on highways, or when the fog is heavy. Rear Windshield Heating: Most cars have a rear windshield heating function, although the button positions may vary, the function is the same. Turn on the windshield heating switch, and the fog on the rear windshield will disappear in about a minute.