Previous investigations of climatic conditions of glaciers primarily focused on the glacier’s surface or on the moulin as the entrance to the glacier’s interior. Many glaciers, however, contain far-reaching cave systems inside the ice that have been understood and investigated as drainage systems for meltwater. Until now, there have been no comprehensive climate studies inside a glacier cave. Thus, the climatic conditions, as well as their effects on the glacier, are unknown. The first climatologic investigations inside the cave system of Sandy Glacier on Mt. Hood in Oregon (USA) in June 2015 have shown that both thermic activity of the volcanic subsurface and chimney effects between the glacier snout at the base of the glacier and higher opening of the moulin can cause drastic melting inside the glacier. Those processes lead to considerably stronger melting from the inside than observations at the surface suggest and can cause an unexpected collapse over a distance of several hundred meters. We will present and assess the first measuring results of both the thermic and flow conditions inside Sandy Glacier
