An outline of subterranean microclimate phenomenology

Under the apparent stability of caves atmospheres, complex meteorological processes amd transient phenomena occur. As a consequence of their very long time scale, such processes play an important role on the overall cave environment. Micrometeorological studies in caves are important in order to estimate paleo‐climatic data reliability, to understand the local adiabaticity, connecting it to the occurrence of complex structures and life, to understand the speleogenetic role of condensation, to characterise caves as ecological “islands” and to protect caves, especially show‐caves, against the anthropic impact. Generally speaking, measures of temperatures in caves in the past represented a qualitative description of their atmosphere, referring mostly to epidermal layers. In general, cave temperatures were considered extremely stable everywhere. Such misconception was in reality a consequence of the low resolution of the old thermometers: a measure of the Earth’s temperature by a thermometer with a resolution of ±50 °C would leave unexplained the presence of deserts, forests and ice caps and the old subterranean measures behaved in a similar way. Nowadays, thanks to a gigantic technological advance in the field of data acquisition and storage, the development of dedicated physical models and advances in the measurement techniques and data processing, the situation is slowly changing and complex patterns emerge. During the presentation we will outline the main microclimatic processes occurring in a cave underlining open problems, with a special interest in the complex phenomenologies of the Bossea show cave. Due to its old history (it is one of the World's oldest show cave) and thanks to the availability of long time series of microclimatic data, we will focus on temperature trends in the last century at Bossea