Abstract
Data from the 1952 Tornado and Severe Storm Observational Network indicate that, pressure waves (abrupt variations in surface pressure) occur frequently in the Central Midwest. These waves are classified and studied statistically for relationships with certain weather phenomena. Elevation type wave lines are found to coincide with certain synoptic discontinuities (squall lines, cold fronts, etc.). Thunderstorm activity accompanied 78 percent of these lines, and tornadoes occurred with 27 percent. Data on the motion of elevation type wave lines, and on the size, amplitude, and duration of their fields of activity are summarized. A marked tendency for these waves to occur during nocturnal hours is found. Depression type wave lines are found not to coincide with ordinary synoptic discontinuities. A combination type wave is described and some speculation on its significance is made. Examination of the relation of tornadoes to pressure waves shows a tendency for tornadoes to occur in specific portions of the elevation wave field.
