1. All processes that add to the mass of the glacier. 2. The mass gained by the operation of any of the processes of sense 1, expressed as a positive number. The main process of accumulation is snowfall. Accumulation also includes deposition of hoar, freezing rain, solid precipitation in forms other than snow, gain of windborne snow, avalanching and basal accumulation (often beneath floating ice). Unless the rain freezes, rainfall does not constitute accumulation, nor does the addition of debris by avalanching, ashfall or similar processes.