“As all drivers know, a foggy windshield isn’t just a nuisance—the low visibility can also make driving more dangerous.
The issue crops up often during winter, when it’s significantly warmer inside the car than it is outside. Basically, hot air can hold much more moisture than cold air; so when the saturated air from the car’s heated interior collides with the cold windows, some of that moisture turns into condensation. Since keeping the temperatures even by never turning your heat on isn’t really an option, former NASA engineer Mark Rober devised a series of experiments to determine how to clear the fog as quickly as possible.”
Read the full story here.
Mr. Rober also suggests that having something in your car to absorb moisture would help to reduce fog as well. He even goes so far as to say that cat litter in a sock would do the trick! Now, that’s probably something you don’t want on your dashboard so swapping out humid air for dry air by cracking the window is a good way to quickly eliminate this fog.