South Carolina Highway Patrol Practice Test - Prep, Practice Questions & Study Guide

A barometer is an instrument specifically designed to measure atmospheric pressure, which is a key factor in weather prediction and understanding climatic conditions. Air pressure changes can indicate impending weather patterns; for instance, a drop in pressure can signal that a storm may be on the way.

While temperature measurement and humidity assessment are important factors in meteorology, they are accomplished through different instruments such as thermometers and hygrometers. Similarly, altitude determination can be done with altimeters or GPS devices, which rely on barometric pressure but serve a distinct purpose focused on elevation rather than general atmospheric pressure readings. Thus, a barometer's primary and direct function is to measure air pressure, making it a crucial tool in meteorological practices.