Book 28, Question 113
How do hockey rinks keep the ice frozen when it's warm outside?
Under the ice of an arena is a floor with pipes that carry a cold liquid, such as chilled salt water.
This pulls heat out of the water above, so it freezes and stays hard. The ice is only about an inch thick. A white coat of paint under it makes the ice look bright, and lines are painted under the surface. Machines keep the temperature steady.