Question

Suppose you hear on the radio that the relative humidity is 90 percent on a winter day. can you conclude that this air contains more moisture than air on a summer day with a 40 percent relative humidity? explain why or why not.

Answer 1

Not necessarily. Relative humidity is a function of the amount of water vapor in the air and the temperature of that air. Warmer air can hold more water vapor than cooler air, thus for a given amount of water vapor, the RH will become higher as the air gets cooler. But again the temperature is important. Thus one cannot say that 90% RH in winter has more moisture than 40% in summer. One needs the associated air temperatures to make that determination.