The NSS Bulletin - ISSN 1090-6924
Volume 53 Number 1: 1-12 - June 1991

A publication of the National Speleological Society

Atmospheric Pressure Changes and Cave Airflow: A Review
Warren C. Lewis


Atmospheric pressure changes play an important role in the movement of air in and out of caves of large volume. These barometric movements are independent of convective airflow or "chimney effect," which is due to change of external temperature. On a tracing of barometric pressure, variatons may appear as random movements or may follow a rhythmic pattern. The period of pattened oscillations, if present, may range from a duration of several weeks to less than one second. They may be characterized as weather cycles, diurnal tides, acoustic-gravity waves or infrasound vibrations. Several varieties will often be superimposed on one another on the tracing from a sensitive barograph. Airflow in the entrance passage of many caves is similar in period to external atmospheric waves. It appears that many phenomena reported as cave breathing and cave resonance may be related to variations in atmospheric pressure.

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