Diurnal cycles of thawing and refreezing can stabilize the snowpack by promoting settlement. Glaciologists subdivide glaciers into glacier accumulation zones, based on the melting and refreezing occurring. Slush refreezing in overnight frost can turn to dangerous slippery ice underfoot. Regelation is the phenomenon of melting under pressure and refreezing when the pressure is reduced. Charlie explains that humans used a process dubbed Global Cooling, refreezing glaciers. During this refreezing process, energy is released in the form of latent heat. This is often misquoted as "refreezing" (see Lewin,1947). This should be done only when refreezing is not a concern.