Melt Freeze Metamorphism

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Metamorphism which results from one or (more commonly) more cycles of melting followed by refreezing. One sequence of melting conditions followed by freezing conditions is called a melt-feeze cycle. This is usually diurnal with melt occuring starting in mid-morning or early aftrenoon and freezing starting when the sun goes down. A period of melt-freeze metamorphism leads to corn snow.

Image:Snow density.jpg

As snow melts water is formed and the force of gravity pulls these molecules downward. In route to the ground they refreeze thickening in the middle stratum. During this refreezing process energy is released in the form of latent heat. As more water comes down from the surface it creates more heat and brings the entire snow pack column to near equal temperature. The firnification of the snow strengthens the snow pack, due to the bonding of grains of snow. Snow around trees and under canopies melts faster due to the reradiation of long wave radiation. As snow gets older particles of impurities (e.g., pine needles, dirt, leaves etc…) accrue within the snow. These darkened objects absorb more short wave radiation causing them to rise in temperature, also reflecting more long wave radiation.

  • 1 The Snow Life-Cycle [1]
  • 2 National Avalanche Center [[2]]

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