What are the methods to solve car window fogging on rainy days?

[Roman]

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 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 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 with the lower temperature will have a lower saturated vapor pressure than the surrounding environment, causing water vapor to gather on the glass surface and form tiny water droplets, resulting in fog. Methods to defog car windows: Air conditioning cooling: Use the dehumidification function of the air conditioning cooling system 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 exhaled air has high humidity, and the windshield will quickly fog up. At this time, you can turn on the air conditioning to blow cold air onto the windshield, using the dehumidification function of the air conditioning to remove the fog on the windshield quickly. 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 front glass and reducing the temperature difference between the inside and outside surfaces of the window glass, which can prevent excessive fogging on the windshield in time. However, it should be noted that the temperature of the rear and side windows rises slowly, so it takes a longer time to remove all the fog. Whether the air conditioning is automatic or manual, turning it on helps with dehumidification; the temperature control of the air conditioning should not be set to the coldest position, otherwise, the outer surface of the windshield may fog up after prolonged use. Spraying anti-fog agents and other preventive measures: 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 can effectively prevent water vapor from condensing on the glass and forming fog, especially suitable for cold winters. Alternatives to anti-fog agents include dishwashing liquid, soapy water, glycerin, alcohol, or salt water. After drying, use chamois or a soft dry cloth to wipe off excess fibers, which can ensure that the car windows do not fog up for several days. Opening windows for convection: If the fog inside the car is not heavy, you can open the windows on both sides to create convection between the inside and outside air, reducing the temperature difference and allowing the fog to disappear slowly. The principle of this method is the same as using cold air from the air conditioning. The disadvantage of opening windows for convection is very obvious: it cannot be used in rainy or snowy weather, on highways, or when the fog is heavy.