I've noticed ice will form on the roof of my car, the front and rear windshields...but not the sides. Why?
Frost can form on a car even when air temperatures are slightly above freezing. That's because metal and glass cool or heat more rapidly than air. The car exterior may cool below freezing when the air is above freezing. That cooling is greatest on surfaces facing 'up', toward the sky. That leads to the fastest frost formation on the hood, top, trunk and windshields.