Why Does the Windshield Fog Up on the Outside in Summer?

[CamilaRose]

In summer, the principle of fogging on the outside of the windshield is similar to that of fogging on the inside in winter. In winter, it occurs due to high humidity inside the cabin meeting the cold glass, forming fog. In summer, if the air conditioning is on, the windshield becomes colder and more prone to fogging. Here is an introduction to car windshields: 1. Windshield Overview: The automotive and glass industries belong to two different sectors—the former is part of mechanical manufacturing, while the latter falls under light industry. However, throughout the development of automobiles, the relationship between the two has grown increasingly close. Glass technology has fully integrated into the automotive industry, becoming an indispensable part of automotive technology. Today, research and development of automotive glass focus on safety and aesthetics, continually introducing new varieties. 2. Function: A car windshield consists of a transparent adhesive plastic film sandwiched between two or three layers of glass, combining the toughness of plastic with the hardness of glass to enhance the glass's resistance to shattering.

[MiguelMarie]

I used to frequently encounter the issue of windshield fogging on the outside during hot summer drives. The main reason was that the car's air conditioning cooled the glass too much, causing the high-temperature, high-humidity air outside to condense into fog upon contact with the glass surface. For instance, that time on the highway when it was scorching hot outside, I had the AC cranked up to the max, and suddenly the windshield became completely fogged up, making it impossible to see anything. I had to slow down and use the wipers a few times. Later, I learned to turn off the AC or raise the temperature a few minutes before parking, allowing the glass to gradually warm up and avoid a drastic temperature difference. Regularly cleaning the windshield also helps reduce fogging, as substances like oil films make it easier for moisture to adhere. In short, summer fogging is quite common, and the key is to maintain a balance between the inside and outside temperatures, ensuring the glass doesn't get too cold, which makes driving much safer.

[MacColton]

I believe this phenomenon is caused by the weather and in-car settings. In summer, the outside humidity and temperature are high, and the cold air from the car's air conditioning drops sharply, causing the windshield to become icy. When the hot and humid outside air comes into contact with it, water vapor condenses into small droplets, forming fog. Sometimes, it's also related to the cleanliness of the glass itself—dust or stains on the glass make it easier for fog to gather. From my experience, parking in an open area in the morning and driving after the sun has been shining on the car makes it particularly noticeable. To prevent this, it's best not to turn off the engine immediately after parking; let the air conditioning run for a while to warm up, or open the windows for a few minutes before driving. Additionally, regularly cleaning the glass with a glass cleaner can help, but don’t rely too much on the wipers—they only provide a temporary fix, not a permanent solution. When there are significant changes in temperature and humidity, driving carefully will ensure safety.