icicle

An icicle is a tapering mass of ice that hangs from a solid surface, formed when water drips and freezes in cold weather. They are common at rooflines, gutters, eaves, or on tree branches, and can also form from dripping meltwater in shaded spots. They are distinct from stalactites, which form in caves by mineral deposition, though both hang from ceilings, but icicles form from freezing water rather than mineral precipitation.

Formation: When liquid water flows or drips in temperatures below 0°C, the water at the tip begins to freeze, and additional water flowing over the surface freezes along the length, producing a slender, elongated pendant. The shape is influenced by the rate of water supply, ambient temperature, air movement, and sunlight. The ice is typically translucent, sometimes bluish, due to the long path that light travels through the crystal and the absence of many air pockets.

Environmental occurrence: Icicles are typical in winter climates with periodic meltwater and freezing conditions. They commonly form on man-made structures such as roofs and gutters, but can also occur on natural features like tree branches. Their size can vary from a few centimeters to over a meter.

Hazards and safety: Large or rapidly growing icicles can detach, posing a hazard to people or property. They are often removed by professionals or with careful manual removal from a safe location, avoiding standing beneath them.

In many regions, icicles are a common winter feature and a visual indicator of freezing conditions.