The cryosphere is vanishing on planet earth - almost everywhere and faster than anticipated. Nevertheless, in some places, such as East Antarctica, more ice may be forming due to increased precipitation and sufficiently cold temperatures. Predictions, however, suffer from the fact that snow deposition and surface mass balance is not quantitatively understood in these extreme environments. This is true for polar regions and the rugged high-mountain environments. Therefore, we propose to investigate precipitation, deposition of snow and the formation of a (permanent) snow cover on high-mountain terrain, glaciers, ice sheets and sea ice. Our work focuses on the processes that happen between the snow production in the clouds and the final deposition and incorporation into the snow and firn cover on the ground. The quantitative contribution of extended snow transport and snow sublimation as well as cycles of snow deposition and re-erosion are not understood sufficiently well. This project will be a milestone with respect to (i) increasing our basic understanding and (ii) creating the modelling basis to be used in weather and climate predictions. The uncertainty in climate change predictions, weather forecasting and the interpretation of firn and ice cores that arises from an insufficient quantitative understanding of these deposition processes is large and has not received sufficient attention in the past. Based on local but spatially distributed (1 km2) measurements of snow mass change and collocated measurements of drifting snow flux, exchange of latent heat (sublimation) and sensible heat as well as general meteorology, snow deposition will be quantitatively understood and will be used to constrain precipitation predictions.