Why Does the Car Window Glass Fog Up on the Outside in Summer?
2 Answers
In summer, car windows fog up on the outside due to the low temperature setting of the car's air conditioning, which creates a significant temperature difference. Additionally, improper air conditioning vent direction can contribute to this issue, such as when the air is directed toward the front windshield or the side windows. Here are some additional details: Detergent-based solutions: Dish soap or soap can be used to prevent fogging on car windows. The principle involves disrupting the attraction between water molecules, reducing surface tension, and evenly distributing water molecules across the treated glass surface. This forms a water film that adheres to the glass—the more rainwater, the larger the water film—keeping the car glass consistently clear. Anti-fog sprays: Anti-fog sprays can be used to remove fog from car windows. The principle involves absorbing moisture on the glass surface to form a water film, which prevents fogging by stopping moisture from adhering to the glass. Wiping the window glass dry with a cloth ensures clarity, with effective and long-lasting results.
Fogging on the outside of car windows is common in summer, primarily because the glass surface temperature is lower than the surrounding air temperature, causing highly humid water vapor to condense into tiny droplets. In hot weather, if we turn on the air conditioning with cold air blowing directly at the windshield, the glass cools rapidly, and the warm, humid outside air quickly forms fog upon contact. This situation is especially prone to occur after rain or in humid areas, as humidity levels above 90% accelerate condensation. When dealing with it, don't panic—adjust the air vents to avoid the glass, switch to external circulation mode, or slightly open a window to balance the temperature difference inside and outside, which can reduce fogging. A gentle swipe with the wipers can clear it, but if it occurs frequently, check the window seals and air conditioning system to ensure proper airflow. This helps avoid obstructing the driver's view and ensures safe driving. It's advisable to carry simple defogging tools during peak summer travel periods as a backup.
