Portal:Physics/Selected picture/Week 52, 2006

Photo credit: Barfooz

Icicles form when the temperature is below zero degrees Celsius and when there is a supply of water. Typically, temperature is just a few degrees below zero and water is melted by the sun, for instance on the roof of a house. Water, under its weight, flows down and freezes, thus increasing icicle's size. If temperature rises, water can no longer freeze, and the icicle can start melting and diminish in size. If weight of an icicle grows too large, the icicle breaks and collapses onto the ground.