USCG Meteorology Practice Exam

A barometer measures atmospheric pressure, which is the force exerted by the weight of the air above a particular point. This instrument is critical in meteorology, as changes in atmospheric pressure can indicate upcoming weather patterns. For example, a falling barometer reading often suggests that a storm may be approaching, while a rising reading can indicate improving weather conditions.

Understanding atmospheric pressure is essential for predicting weather changes, as it influences wind patterns and precipitation. Other options do not pertain to what a barometer measures; humidity, wind speed, and temperature are measured by different specific instruments designed for those purposes. Thus, the focus of a barometer is solely on atmospheric pressure, making it an essential tool for meteorologists in weather forecasting and analysis.