Why Does Fog Form on the Car Windows When It Rains?
2 Answers
Fogging on car windows during rain is primarily caused by the atomization of air inside the vehicle. This phenomenon occurs when the glass is cold while the air inside the car is warm, leading to the release of heat and the formation of tiny water droplets. Solutions: 1. Open the windows for ventilation: Fogging inside the car is due to high humidity in the cabin. One method is to open the windows for ventilation, while another is to turn on the air conditioning with cold air directed towards the windshield, which quickly eliminates the fog. 2. Wipe and clean: Turn on the air conditioning to adjust the interior temperature, removing the fog inside the car and causing the frost on the windows to melt quickly. Applying a thin layer of glycerin or alcohol on the windshield can prevent frost formation on the glass surface for a short period. Dissolving dishwashing detergent in water and applying it with a clean cloth to the inside of the windshield will produce many bubbles. Wait a moment, and the bubbles will disappear on their own, leaving a detergent film on the glass that effectively prevents frost for up to 2 hours. Once the interior temperature rises, use a clean, damp cloth to wipe off the liquid film from the glass.
When the car windows fog up while driving in the rain, I have to say it's mainly caused by temperature differences and humidity. The outside temperature drops when it rains, cooling the car windows. The moisture from passengers talking or breathing inside the car condenses into tiny water droplets when it meets the cold glass. It's just like how windows fog up indoors during winter. Fogged-up windows create dangerously blurred vision, especially on rainy days when roads are slippery—extra caution is needed. When I encounter this situation, I immediately turn on the car AC's dehumidification mode and adjust the airflow toward the windshield; it clears up in minutes. If the AC isn't effective, I crack open a window slightly to ventilate and reduce humidity. For long-term prevention, regularly change the air filter to maintain interior dryness and prevent moisture buildup. This issue isn't major, but if neglected, it can compromise safety—so it's important to address it promptly.
