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Abstract
Castleguard Cave has a climate dominated by chimney-effect winds, due to temperature differences between interior and exterior air. A theory is developed relating the magnitude of winds to these differences and to friction at cave walls. Friction factors derived are the first for cave conduits, and agree with values expected from wall roughness and known values from mines.
Radon-222 content of air and waters indicates that radon is added to cave air by exhalation, direct emanation, and diffusion from cracks in rock around principal passages. Radon dilution in the central cave is attributed to tributary air currents from larger fissures. These results demonstrate that the cave is embedded in a porous medium which has a significant influence on air flows.
Temperature profiles demonstrate geothermal heating of the central cave. Isotherms on a cross section of Castleguard Mountain indicate that conductive heat flow to the base of the Columbia Icefield is substantially less than to adjacent ice-free areas, due to abstraction by meltwaters percolating downwards from the ice.
Relative humidity and vapor pressure profiles show rapid increases of water content in dry air blowing into the entrance, as predicted by theory. In the central cave, temperature and vapor pressure profiles reflect heat and moisture exchange with the walls. These predominate over adiabatic effects. Evaporation amounts to a few millimeters of water per year.