Suppose it is a winter night and at about 11 p.m., the air cools to the dew-point temperature and a thick radiation fog develops. If the air continues to cool during the night, in 5 hours the dew point temperature will probably:

The correct answer is: A. Decrease as the air becomes drier.

The dew point temperature is the temperature at which the air is saturated with water vapor. If the air cools below the dew point temperature, water vapor will condense out of the air and form dew. This is why you often see dew on the grass in the morning after a cool night.

In the scenario described in the question, the air is already saturated with water vapor at 11 p.m. If the air continues to cool, the dew point temperature will decrease as the air becomes drier. This is because the air can hold less water vapor at lower temperatures.

Option B is incorrect because the air will become drier, not moister, as it cools. Option C is incorrect because the dew point temperature is a measure of the amount of water vapor in the air, not the temperature of the air. Option D is incorrect because the dew point temperature will decrease, not increase, as the air cools.