Accumulation by snowfall

Glacier mass balance data from the World Glacier Monitoring Service

The main means by which a glacier gains mass is from snow falling onto the surface of the glacier. Typically, more snow falls at higher elevations than at lower elevations in the mountains, because mountains force the air upwards, which cools it down and makes precipitation more likely. This effect is called orographic precipitation (Holden 2012: 6). This typically means that a graph of accumulation versus elevation would be more positive at the top of the glacier (where most snow falls) and less positive at the bottom.

Because most snow falls in the winter, the total amount of snow accumulated by springtime is known as the winter balance.