Atmospheric icing

Atmospheric icing occurs when water droplets in the air freeze on objects they contact.

Atmospheric icing is very dangerous on aircraft, as the built up ice changes the aerodynamics of the flight surfaces, and can cause loss of lift, with an increased risk of a subsequent crash.

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, icing is rare because clouds at these temperatures usually consist of ice particles rather than supercooled water droplets. Below -40^oC it is generally accepted that icing on aircraft is negligible.

Icing also occurs on towers, wind turbines, boats, oil rigs, trees and other objects exposed to low temperatures and water droplets.

Look at the following picture that shows aircraft with icing on...

1. ^{Icing (food)}
2. ^{Icing (shipping)}
3. ^{Icing (ice hockey)}
4. ^{Icing by Claire's}
5. ^{A periglacial ice sheet (aufeis)}