The instrument that can measure atmospheric pressure is a barometer. Barometers are essential tools in meteorology, allowing scientists and weather enthusiasts to predict weather patterns and understand atmospheric pressure changes. There are two main types of barometers: mercury barometers, which use mercury in a glass tube, and aneroid barometers, which measure pressure changes with a metallic diaphragm that expands or contracts. Barometer readings can indicate weather trends—falling pressure often suggests storms, while rising pressure may indicate fair weather. Understanding atmospheric pressure is crucial for various applications, including aviation and climate studies.