What are the reasons why the fog on the outside of the windshield cannot be blown away?
2 Answers
The reason why the fog on the outside of the windshield cannot be blown away is the temperature difference between the inside and outside of the vehicle. The temperature inside the cabin is higher than outside, causing moisture inside the cabin to condense. Solutions to remove fog from the outside of the windshield include: 1. Wiping it clean with a towel; 2. Turning on the car's heater to clear the fog; 3. Using the air conditioning's cooling and dehumidifying function to reduce air humidity; 4. Applying an automotive glass anti-fog agent. The functions of the car windshield are: 1. Protecting against wind and rain, and reducing noise; 2. Reducing wind resistance and improving airflow; 3. Ensuring the safety of passengers. Methods to maintain car glass include: 1. Using dedicated or suitable wiper blades and replacing them promptly; 2. Keeping the windshield clean; 3. Using automotive-specific glass cleaner.
I've been driving for almost twenty years and have seen this situation many times. Fogging on the outside of the windshield is mainly caused by high external humidity or significant temperature differences, leading to water vapor condensing directly on the glass. The defogging button is designed to clear internal fog by heating or cooling through the car's air conditioning system, and it doesn’t help much with external fog. When the fan speed is insufficient or the air conditioning settings are incorrect, its effectiveness is even less noticeable. For daily driving, I’d recommend regularly checking if the wipers are worn out during rainy or humid weather, and using specialized glass cleaners when washing the car to reduce oil film buildup. For prevention, keeping a clean cloth in the car for a quick wipe is the most straightforward solution. Never compromise on safety—if visibility is poor, pull over and stop rather than risk driving.
