average weather (climate) for the regions above the tree line
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- "World Biomes: Alpine". Kids Ecology. University of California at Santa Barbara. Retrieved February 4, 2022.
- "Alpine (High Elevation) Life Zones". Biomes of the World. Radford University. Retrieved February 4, 2022.
- McKnight, Tom L; Hess, Darrel (2000). "Climate zones and types: the Köppen system". Physical geography: a landscape appreciation. Upper Saddle River, New Jersey: Prentice Hall. pp. 235–7. ISBN 0-13-020263-0.