What happens to the air's humidity for every 20°F increase in temperature?

The correct answer indicates that for every 20°F increase in temperature, the air's humidity effectively doubles. This is based on the concept of saturation vapor pressure, which describes how much moisture air can hold at different temperatures. As air temperature rises, the capacity of the air to hold water vapor increases substantially, thereby allowing it to contain more moisture.

Specifically, for approximately every 20°F (about 11°C) increase in temperature, the saturation vapor pressure increases by a factor of roughly 2. This means that warm air can hold significantly more water vapor than colder air, which is why relative humidity can be understood in this context. Thus, when temperature rises, the absolute humidity—amount of water vapor in the air—can increase, leading to the idea that air's humidity doubles under these conditions.

This relationship between temperature and humidity is crucial in meteorology and understanding weather patterns, as it helps predict conditions like dew point and potential for precipitation, which directly relate to changes in temperature and humidity.