Breathing cave

A breathing cave or barometric cave is a rare type of cave in which atmospheric pressure gradients between the inside and outside of a cave cause air to flow in to or out of the cave. The concept of air flowing through a cave is common, however in most caves this airflow is caused by a difference in temperature rather than air pressure; in barometric caves the thermal mechanism inside the cave is not great enough to cause such airflow. The speed of the airflow in barometric caves is directly correlated with the atmospheric pressure difference between the inside and outside of the cave. When the air pressure outside of the cave is higher than that inside the cave air blows into the cave and vice versa; if the air pressures are at equilibrium there is no airflow.

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