What does humidity measure?

The correct answer is the measure of the amount of water vapor in the air. Humidity is a key concept in meteorology that indicates how much moisture is present in the atmosphere. This measurement can be expressed in several ways, including absolute humidity, relative humidity, and specific humidity.

Relative humidity, for instance, compares the current amount of water vapor in the air to the maximum amount of water vapor that the air can hold at a given temperature. This is crucial for understanding weather patterns, as higher humidity levels often correlate with discomfort and can lead to conditions such as storms or fog.

In contrast, the other options focus on different atmospheric measurements. For example, atmospheric pressure measures the force exerted by the weight of air above a given point, which is a distinct concept from humidity. The concentration of pollutants assesses air quality, and temperature measures thermal energy in the air. None of these directly address the moisture content in the atmosphere, which is what humidity specifically measures.