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 heat leaking from the interior of a heated 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.
Damage and injuries caused by icicles 
Icicles can pose both safety and structural dangers. Icicles that hang from an object may fall and cause injury and/or damage to whomever or whatever is below them. In addition, ice deposits can be heavy. If enough icicles form on an object, the weight of the ice can severely damage the structural integrity of the object and may cause the object to break.
Armstrong, the scientist from the National Snow and Ice Data Center, told a journalist, "Another twist is very large icicles falling from cliffs along highways hitting cars. Where I used to work doing avalanche hazard assessment and forecasting along U.S. Highway 550 in southwestern Colorado, icicles have fallen and destroyed passing cars."
In 2010, five people were killed and 150 injured by icicles in Saint Petersburg, Russia after a heavy snow that also caused apartment block roofs to collapse, as well as creating water damage to private homes and to the National Library of Russia.
Kathleen F. Jones of the U.S. Army Cold Regions Research and Engineering Laboratory states, "The combination of the ice load and the wind on ice load can break wires, cross arms, and poles and/or other supporting structures. Damage associated with icicles on roofs may be to vehicles parked next to the overhang. Icicles on roofs are also often associated with ice dams that may cause water to infiltrate under the shingles with possible water damage to the house or building and its contents."
See also 
- Ribas, Jorge (February 9, 2010). "Snowmageddon Brings Icicles of Doom". Discovery News. Retrieved September 19, 2012.
- CityNews.ca - Dangerous Icicles A Concern As Pieces Fall From Above
- Sporting Magazine: or, Monthly Calendar of the Transactions of The Turf, The Chase, and Every Other Diversion Interesting to the Man of Pleasure, Enterprise, and Spirit, Vol. 27. London: J. Wheble. 1806. p. 95.
- Billing, Joanna (2003). The Hidden Places of Devon. Aldermaston, England: Travel Publishing Ltd. p. 51.
- Simons, Paul (17 February 1999). "Weatherwatch". The Guardian. Retrieved September 19, 2012.
- Streever, Bill (2009). Cold: Adventures in the World's Frozen Places. New York: Little, Brown and Company. p. 147. "In 1776, a son of the parish clerk of Bampton in Devon, England, was killed by an icicle that plummeted from the church tower and speared him. His memorial: Bless my eyes / Here he lies / In a sad pickle / Kill'd by an icicle."
- Osborn, Andrew (24 March 2010). "Falling icicles kill record numbers in St Petersburg". The Daily Telegraph. Retrieved September 19, 2012. "Russians risk their lives each year as winter becomes spring causing melting icicles and blocks of ice to fall from roofs, often from a great height, onto defenceless pedestrians below. Regional figures show icicles kill dozens of Russians each year."
- 'Brinicle' ice finger of death filmed in Antarctic
- "The underwater icicle of death: Bizarre 'Brinicle' forms BENEATH the sea and kills everything in its path". Daily Mail Online. 24 November 2011. Retrieved September 19, 2012.
- Praetorius, Dean (November 23, 2011). "Brinicle, Underwater Icicle, Captured Forming By Time-Lapse Camera". The Huffington Post. Retrieved September 19, 2012.
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