How to Deal with Foggy Side Windows on a Rainy Day?

[LeHannah]

Press the defogging button, turn on the air conditioning cooling (A/C) switch, set the temperature to the lowest, and use the external circulation to remove fog. Both cold and warm air can defog car windows, but warm air works slower than cold air. The most effective method is using cold air, which blows dry cold air directly onto the glass, preventing water vapor from condensing on the glass and achieving defogging. The method for warm air defogging is the same as cold air, but note that using warm air on rainy days may initially worsen the fog. Always use external circulation when defogging car windows. The reason for car window fogging: There is a temperature difference between the inside and outside of the car. If the temperatures differ, the surface with the lower temperature has a lower saturated vapor pressure than the surrounding environment, causing water vapor to gather on the glass surface and form tiny droplets, resulting in fog. Methods for defogging 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 without turning on the air conditioning, the exhaled humid air can quickly cause the windshield to fog up. Turning on the air conditioning to blow cold air onto the windshield and using the dehumidification function can quickly remove the fog. If the humidity is too high and the air conditioning is ineffective, slightly opening the windows can quickly reduce the humidity inside the car. Combining both methods can yield faster results. Air Conditioning Warm Air: Use warm air to reduce the temperature difference and remove fog. In winter, blowing warm air onto the windshield quickly raises its temperature, reducing the temperature difference between the inside and outside surfaces and preventing heavy fogging. However, the rear and side windows heat up slower, so it takes longer to remove all the fog. Whether the air conditioning is automatic or manual, turning it on helps with dehumidification. Avoid setting the temperature to the coldest to prevent frost on the outside of the windshield. Applying Anti-Fog Agents: Spray a small amount of defogging agent on the car windows and wipe it clean to remove dirt and stains. This leaves a thin transparent protective film that effectively prevents water vapor from condensing on the glass, especially useful in cold winters. Alternatives to defogging agents include dish soap, soapy water, glycerin, alcohol, or salt water. After applying and letting it dry, wipe off any excess with a soft cloth to keep the windows fog-free for several days. Opening Windows for Airflow: If the fog inside the car is not too heavy, opening the side windows can create airflow between the inside and outside, reducing the temperature difference and gradually eliminating the fog. This method works on the same principle as using cold air from the air conditioning. However, it has obvious drawbacks and cannot be used during rain, snow, on highways, or when the fog is heavy. Rear Window Heating: Most cars have a rear window heating function, though the button location may vary. Turning on the rear window heating switch will clear the fog in about a minute.