Acta Musei Moraviae

Wall surface temperature as an indicator of the changes in cave airflow on the example of the ventilation branch in the Balcarka Cave (Moravian Karst)

Seasonal variations of wall surface temperature in the ventilation branch of the Balcarka Cave (Moravian Karst) were studied focuted on their relationship to changes in cave airflow. Long-term monitoring of differences between external and cave air temperatures showed dynamic airflows that can be divided into downward (DAF mode) and upward (UAF mode) airflows. Switch between DAF and UAF modes occurred in late fall or early spring, corresponding to the transitional mode, however, it also occurred during peak DAF/UAF modes. Temperatures of the wall surface in the lower part of the ventilation branch were found to be systematically higher than temperatures in the upper part of the branch. The principal reason is heat transfer between the cave air and the walls. While warm external air contributed to a general temperature increase during DAF mode, cool external/cave air resulted in a significant temperature decrease during UAF mode. However, this pattern could be disrupted by short-term changes in cave ventilation induced both naturally (ventilation mode switching) and anthropogenically (visiting route modification).