What does barometric pressure measure?

Barometric pressure specifically measures the weight of the atmosphere above a given point and is typically expressed in units such as millibars or inches of mercury. This measurement is crucial for understanding weather patterns, as it provides information about the state of the atmosphere and can indicate whether conditions are stable or unstable.

When the barometric pressure is high, it usually suggests fair weather because it often correlates with descending air that tends to clear out clouds. Conversely, low barometric pressure is often associated with stormy weather as it indicates rising air, which can lead to cloud formation and precipitation. The other choices represent different atmospheric phenomena—humidity measures the amount of moisture in the air, wind speed describes how fast air is moving, and temperature indicates how hot or cold the air is—none of which are directly related to the concept of barometric pressure.