Does a barometer fall or rise when there is a tornado?
A barometer measures air pressure and, since a tornado is a center of relatively low pressure, the barometer would register a fall in pressure as a tornado approached and struck. The inward-spiraling winds of tornadoes move a tremendous amount of air, plus debris, from near the ground and funnel it up and into its parent thunderstorm cloud (the heaviest debris falls back to earth near the tornado). With less air near the ground the pressure drops. Aneroid barographs, which trace the pressure level on graph paper, usually show at least some kind of downward spike in pressure as a tornado passes. But, the pressure change in a tornado is so much more rapid than in a hurricane or winter storms it can change as much in seconds as a hurricane would in hours that the needles on most barographs have difficulty measuring the actual pressure change in a tornado. This usually is because they respond too slowly to the quick pressure change. To learn more about barometers and barographs, start by c
