Air Currents  Cave tourVisitors frequently ask if the cave will
ever run out of oxygen or if noxious gases like methane or
carbon dioxide can build to the point of toxicity. In Crystal
Cave the answer is NO! Most caves are very well ventilated and
Crystal Cave is no exception. The cave is ventilated by
exchanging air with the outside. This process is accomplished
through the changing barometric pressure. Outside the cave, air
is warmed during the day. As it warms it becomes less dense and
the barometric pressure falls. When the outside pressure falls,
the air flows out of the cave. At night the air is cooled,
becoming more dense causing the pressure to rise. Air will be
drawn into the cave during the night. Other pressure changes are
related to the weather like those changes which accompany the
passage of a storm front. These pressure changes are
superimposed upon the daily fluctuation. The cave pressure
adjusts to conform to the resultant effect of both.  Temperature
will also affect air movement. If the cav