Glaciating in Clouds Over Sparta, Greece

June 01, 2015

Cloud GlaciationIMG_0485_1500xxr

Photographer: P. Nikolakakos
Summary Author: P. Nikolakakos; Jim Foster

The photo above showing a sky filled with glaciated mid-level clouds as observed over Sparta, Greece on May 18, 2015. Ice crystals are falling from altocumulus clouds and sublimating in the drier, warmer air just below the cloud level. These clouds consist of supercooled water droplets. When these droplets freeze they grow quite rapidly because the vapor pressure of water vapor over ice is small compared to the vapor pressure of water vapor over liquid water. The resulting ice crystals are heavy enough to fall from the clouds -- as virga.