Why does the outside of a car's windshield fog up?

[VanOlive]

The main reasons are temperature issues and high humidity inside the car. Here are some related explanations about defogging: 1. Causes of fogging inside the car: The primary cause of fogging inside the car is temperature-related. When the temperature inside the car is higher than outside, the windows are more prone to fogging. Another reason is the high humidity inside the car, combined with the warm breath of passengers. When this warm air meets the cold glass, condensation occurs, leading to fogging on the windows. 2. Best way to handle fogging inside the car: The quickest and most effective method is to turn on the air conditioning's cold air. By activating the air conditioning's cooling function along with the external circulation, the fog on the glass should disappear in less than a minute. During autumn or winter, you can use the air conditioning's warm air to blow on the windshield.