Icicle

An icicle is a spike of ice formed when water dripping or falling from an object freezes.
Formation and dynamics
Typically, icicles will form when ice or snow is melted by either sunlight or some other heat source (such as a poorly insulated building), and the resulting melted water runs off into an area where the ambient temperature is below the freezing point of water (0 °C/32 °F), causing the water to refreeze. Over time continued water runoff will cause the icicle to grow.
Richard Armstrong, a senior research scientist at the National Snow and Ice Data Center in Boulder, Colorado, has explained why icicles come in various shapes and sizes. Icicles form on surfaces which might have a smooth and straight, or irregular shape, which in turn influences the shape of an icicle. Another influence is melting water, which might flow toward the icicle in a straight line or which might flow from several directions.
Given the right conditions, icicles...