Altimeter on the Matterhorn. An altimeter is a device that measures altitude—a location's distance above sea level. Most altimeters are barometric, meaning they measure altitude by calculating the location's air pressure. Air pressure decreases as altitude increases.
Altimeter on the Matterhorn. An altimeter is a device that measures altitude—a location's distance above sea level. Most altimeters are barometric, meaning they measure altitude by calculating the location's air pressure. Air pressure decreases as altitude increases.