Why do finger drawings made on fogged up gl (like cars whn its cold outside) reappear next time they fog up?

Like when youre in a car and the windows are foggy because there's water condensed on them, and so you can write things or draw on them. Then you'll get in the car 2 days later and the windows will fog up again, and you can see what ever you wrote 2 days ago? How does this happen scientifically?