Dependence of radon levels in Postojna Cave on outside air temperature

摘要: Abstract. Postojna Cave is the largest of 21 show caves in Slovenia. The radon concentration there was measured continuously Great Mountain hall from July 2005 to October 2009 and ranged about 200 Bq m−3 winter 3 kBq summer. observed seasonal pattern governed by air movement due difference external internal densities, controlled mainly temperature. cave behaves as a large chimney cold period, warmer released vertically through cracks fissures colder outside atmosphere, enabling inflow fresh with low levels. In summer ventilation minimal or reversed flows higher lower openings cave. Our calculations have shown that effect between temperatures on delayed for four days, presumably because distance measurement point entrance (ca. 2 km). A model developed predicting basis temperature has been checked found be successful.