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In order for something to freeze, it must be able to give off its heat. When the temperature of the outside air drops, both a road and a bridge begin to give up their heat to the cold air. But the road, being in contact with the ground, is continually rewarmed by heat rising from below the earth’s surface. The bridge being, for the most part, suspended in air, is not rewarmed in this manner and so freezes first.
From: More Ever Wonder Why? By: Douglas B. Smith |
