And if poor absorbers were good emitters, their temperatures would fall below that of better absorbers. A good reflector is a poor radiator of heat, and a poor reflector is a good radiator of heat. Put the cream in right away for at least three reasons. Also, by Newton's law of cooling, the higher the temperature of the coffee above the surroundings, the greater will be the rate of cooling-so again add cream right away and lower the temperature to that of a reduced cooling rate, rather than allowing it to cool fast and then bring the temperature down still further by adding the cream later. Also-by adding the cream, you increases the total amount of liquid, which for the same surface area, cools more slowly.
Heat radiates into the clear night air and the temperature of the car goes down.
Normally, heat is conducted to the car by the relatively warmer ground, but the rubber tires prevent the conduction of heat from the ground. So heat radiated away is not easily replaced and the car cools to temperatures below that of the surroundings. Under open skies, radiation is only from the ground and frost forms. Under the benches, downward radiation of the benches decreases the net radiation from the ground, resulting in warmer ground and, likely, no frost. The white house is also a poor radiator, so when the house is warmed by fuel inside, its whiteness reduces the radiation it emits to the surrounding.