"Equilibrium line” is the point on a glacier that separates the “accumulation zone”, where snow adds to the glacier’s mass, from the “ablation zone”, where melting subtracts from it. [...] Plenty of snowfall, or a cool summer, and the [equilibrium] line will move downhill. A dry winter or a scorching summer will move it higher.

https://www.economist.com/science-and-technology/2023/09/27/glaciers-on-volcanoes-could-serve-as-early-warning-systems

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