Atmospheric icing

The effect of atmospheric icing on a tree.

Atmospheric icing occurs when water droplets in the atmosphere freeze on objects they contact. This can be extremely dangerous to aircraft, as the built-up ice changes the aerodynamics of the flight surfaces, which can increase the risk of a subsequent stalling of the airfoil. For this reason, ice protection systems are often considered critical components of flight, and aircraft are often deiced prior to take-off in icy environments.

Not all water freezes at 0 °C or 32 °F. Liquid water below this temperature is called supercooled, and such supercooled droplets cause the icing problems on aircraft. Below −20 °C (−4 °F), icing is rare because clouds at these temperatures usually consist of ice particles rather than supercooled water droplets. Below −48 °C (−54.4 °F), supercooled water cannot exist, therefore icing is impossible.[1]

Icing also occurs on towers, wind turbines, boats, oil rigs, trees and other objects exposed to low temperatures and water droplets. Ice loads are a major cause of catastrophic failures of overhead electric power lines. Their estimation is, therefore, crucial in the structural design of power line systems.[2] and can be done by numerical icing models that include meteorological data.[3]

Aircraft incidents

Main article: Icing conditions

A number of aircraft crashes have been caused by ice. In other incidents icing was a contributory factor.

See also


  1. Moore, Emily; Valeria Molinero (24 November 2011). "structural transformation in supercooled water controls the crystallization rate of ice". Nature. 479: 506–508. arXiv:1107.1622Freely accessible. Bibcode:2011Natur.479..506M. doi:10.1038/nature10586.
  2. Farzaneh, M. (2008) Atmospheric Icing of Power Networks. Springer Science & Business Media, 2008, 381 p. ISBN 978-1-4020-8530-7
  3. Makkonen, L. (2000) Models for the growth of rime, glaze, icicles and wet snow deposits on structures. Philosophical Transactions of the Royal Society, London A, 358 (1776): 2913-2939.

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