Snowlines

Snowlines are boundaries on a surface where snow begins to persist. In glaciology and mountain geography, the snowline (often called the permanent snow line) marks the lowest elevation at which snow remains year‑round, separating snow‑covered terrain from snow‑free ground. Its altitude varies with latitude, season, and local climate, and it can shift with weather patterns and longer-term climate change.

The snowline is influenced by temperature, precipitation, solar radiation, wind, and the balance between snowfall and melt. Snowlines can be perennial, remaining above a fixed elevation, or seasonal, moving up and down through the year. They are commonly mapped through field observations, aerial reconnaissance, and satellite imaging, and are used in studies of glacier size, water resources, and alpine ecosystems.

In astronomy, the snow line (also called the ice line or frost line) refers to the distance from a star in a protoplanetary disk where temperatures are low enough for volatile substances, notably water, to condense into ice on dust grains. Inside this line, water tends to stay vaporous; outside, ice can form. The snow line influences the chemical makeup and growth of planets and planetesimals, contributing to distinctions between rocky and icy bodies in developing planetary systems.

Overall, snowlines serve as useful indicators of climatic conditions on Earth and of thermal structure in planetary nurseries, linking surface processes with broader environmental and astrophysical contexts.