A term generally used to refer to the elevation of the lower edge of a snow field. In mountainous areas, it is not truly a line but rather an irregular, commonly patchy border zone, the position of which in any one sector has been determined by the amount of snowfall and ablation. These factors may vary considerably from one part to another.

In regions where valley glaciers descend to relatively low elevations, the summer snow line on intervening rock ridges and peaks is often much higher than the snow line on the glaciers, and in most instances it is more irregular and indefinite. If by the end of summer it has not disappeared completely from the bedrock surfaces, the lowest limit of retained snow is termed the orographical snow line, because it is primarily controlled by local conditions and topography. On glacier surfaces it is sometimes referred to as the glacier snow line or névé line (the outer limit of retained winter snow cover on a glacier).