Some caves seem to breathe.

Not because they are alive, but because air moves in and out of them as weather conditions change above ground.

As temperatures and atmospheric pressure shift, the air inside a cave can respond.

When outside pressure changes, air may be pushed into the cave or drawn back toward the surface.

Temperature differences can create another effect.

Cold, dense air can move differently from warmer air, producing currents through passages, cracks, and entrances.

In some caves, these movements are strong enough to feel like a steady breeze.

The deeper and more complex the cave system, the more fascinating the effect can become.

Some caves have narrow openings that act almost like natural vents.

Others contain multiple entrances at different elevations, allowing temperature dif ...