Climate snow line
From Glossary of Meteorology
climate snow line
(Also called climatic snow line.) The altitude above which a flat surface (fully exposed to sun, wind, and precipitation) would experience a net accumulation of snow over an extended period of time. Below this altitude ablation would predominate.
While this concept is largely theoretical in application, it corresponds closely to the actual firn line of a glacier and to the average summer position of the snow line in mountainous terrain.