Cave climate: Assessment of airflow and ventilation

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Publication Date

10-1-1982

Publication Title

International Journal of Climatology

Volume Number

2

Issue Number

4

Abstract

Study of cave climates is a neglected aspect of microclimatology. An understanding of the processes that control cave climate is required in the study of cave flora and fauna, thermodynamic conditions for karst processes underground, hydrogeologic features of speleothems as well as human use of caves for recreational and commercial purposes. An understanding of cave airflow is of central importance as the climate of a cave is a function of air exchange with the outside environment. The study site is the Glowworm Cave of New Zealand and is of particular interest because of its heavy visitor use and the presence of climate sensitive cave fauna on which the value of the cave as a tourist attraction depends. The study examines airflow using conventional methods together with experimental procedures using SF6 and CCl2F2 tracer gases. The results show that the rate and direction of airflow are a direct response to a thermally induced disequilibrium in air density between the cave and outside air. Both diurnal and seasonal patterns in the direction of airflow were identified. Reversal of airflow occurs when the cave to outside air density gradient is zero rather than when thermal conditions of the cave and external air are the same. Major and minor airflow routes through the cave were identified. The results of the gas tracer experiments allowed estimation of rates of air change in different parts of the cave and confirm the marked difference in ventilation that occurs within the cave. Information of this type is important because of the relationship between natural ventilation and CO2 buildup. There is also the effect of ventilation on differences in climate within the cave as the thermal and moisture effects of outside air will not be as pronounced in parts of the cave where air change is limited.

Keywords

Caves, Airflow, Microclimatology, Ventilation, Speleology

Document Type

Article

Digital Object Identifier (DOI)

https://doi.org/10.1002/joc.3370020408

Language

English

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