Atmospheric icing occurs when
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
dropletsA drop or droplet is a small volume of liquid, bounded completely or almost completely by free surfaces. A drop may form when liquid accumulates at the lower end of a tube or other surface boundary, producing a hanging drop called a pendant drop...
in the
atmosphereAn atmosphere is a layer of gases that may surround a material body of sufficient mass, by the gravity of the body, and are retained for a longer duration if gravity is high and the atmosphere's temperature is low...
freezeFreeze may refer to:In liquids turning to solids:*Freezing, the physical process of a liquid turning into a solid*Freeze drying, a method of rapidly removing moisture from food productsIn cessation of movement or change:...
on objects they contact. This is very dangerous on
aircraftAn aircraft is a vehicle which is able to fly by being supported by the air, or in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil An aircraft is a vehicle which is able to fly by being supported...
, as the built-up
iceIce is a solid phase, usually crystalline, of a non-metallic substance that is liquid or gas at room temperature, such as carbon dioxide ice , ammonia ice, or methane ice. However, the predominant use of the term ice is for water ice, technically restricted to one of the 15 known crystalline phases...
changes the
aerodynamicsAerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...
of the flight surfaces, which can increase the risk of a subsequent stalling of the
airfoilAn airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....
.
Not all water freezes at 0°C or 32°F. Liquid water below this temperature is called
supercooledSupercooling is the process of lowering the temperature of a liquid or a gas below its freezing point, without it becoming a solid.A liquid below its standard freezing point will crystallize in the presence of a seed crystal or nucleus around which a crystal structure can form...
, and such supercooled droplets cause the icing problems on aircraft.
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Atmospheric icing occurs when
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
dropletsA drop or droplet is a small volume of liquid, bounded completely or almost completely by free surfaces. A drop may form when liquid accumulates at the lower end of a tube or other surface boundary, producing a hanging drop called a pendant drop...
in the
atmosphereAn atmosphere is a layer of gases that may surround a material body of sufficient mass, by the gravity of the body, and are retained for a longer duration if gravity is high and the atmosphere's temperature is low...
freezeFreeze may refer to:In liquids turning to solids:*Freezing, the physical process of a liquid turning into a solid*Freeze drying, a method of rapidly removing moisture from food productsIn cessation of movement or change:...
on objects they contact. This is very dangerous on
aircraftAn aircraft is a vehicle which is able to fly by being supported by the air, or in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil An aircraft is a vehicle which is able to fly by being supported...
, as the built-up
iceIce is a solid phase, usually crystalline, of a non-metallic substance that is liquid or gas at room temperature, such as carbon dioxide ice , ammonia ice, or methane ice. However, the predominant use of the term ice is for water ice, technically restricted to one of the 15 known crystalline phases...
changes the
aerodynamicsAerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...
of the flight surfaces, which can increase the risk of a subsequent stalling of the
airfoilAn airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....
.
Not all water freezes at 0°C or 32°F. Liquid water below this temperature is called
supercooledSupercooling is the process of lowering the temperature of a liquid or a gas below its freezing point, without it becoming a solid.A liquid below its standard freezing point will crystallize in the presence of a seed crystal or nucleus around which a crystal structure can form...
, 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
towerTowers are tall structures that are almost always taller than they are wide, usually by a significant margin. Towers are generally built to take advantage of their height, and can stand alone or as part of a larger structure.- History :...
s,
wind turbineA wind turbine is a rotating machine which converts the kinetic energy of wind into mechanical energy. If the mechanical energy is used directly by machinery, such as a pump or grinding stones, the machine is usually called a windmill...
s,
boatA boat is a watercraft of modest size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is...
s,
oil rigsA drilling rig is a machine which creates holes and/or shafts in the ground. Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells, or natural gas extraction wells or they can be small enough to be moved manually by one person...
, trees and other objects exposed to low temperatures and water droplets.
Related aircraft incidents
- 26 Dec 1989 United Airlines Flight 2415
- 31 Oct 1994 American Eagle Flight 4184
American Eagle Flight 4184, was a regional airline flight that crashed after flying into known icing conditions on Halloween, October 31, 1994. Control was lost and all aboard were killed.-History:...
- 9 Jan 1997 Comair Flight 3272
Comair Flight 3272 was a Comair flight departing on January 9, 1997, from Cincinnati/Northern Kentucky International Airport for the Detroit Metropolitan Wayne County Airport. While on approach for landing, the aircraft, an Embraer EMB 120 Brasilia, crashed nose-down 18 miles short of the airport...
- 19 Mar 2001 Comair Flight 5054
Comair Flight 5054 was an Embraer EMB 120 Brasilia departing on March 19, 2001 from Nassau International Airport for the Orlando International Airport. While in route the plane experienced severe icing conditions resulting in a rapid loss of altitude. The crew was able to recover control of the...
- 12 Feb 2009 Continental Connection Flight 3407
See also
- Deicing
De-icing is the process of removing frozen contaminant, snow, ice, slush, from a surface.Anti-icing is the process of protecting against the formation of frozen contaminant, snow, ice, slush on a surface....
- Anti-icing
- Ice protection system
- Hard rime
- Soft rime
Soft rime is a white ice deposition that forms when the water droplets in light freezing fog or mist freeze to the outer surfaces of objects, with calm or light wind...
- Frost
Frost is the solid deposition of water vapor from saturated air. It is formed when solid surfaces are cooled to below the dew point of the adjacent air. Frost crystals' size differ depending on time and water vapor available. Frost is also usually translucent in appearance. There are many types of...
- White frost
White frost is a solid deposition of ice which forms directly from water vapour contained in air.White frost forms when there is a relative humidity above 90% and a temperature below -8 °C . The developing heat is then transferred to air by convection...
- Condensation
Condensation is the change of the physical state of aggregation of matter from gaseous phase into liquid phase and the reverse of evaporation. When the transition happens from the gaseous phase into the solid phase directly, bypassing the liquid phase, the change is called deposition...
- Supercooled liquid water and airframe icing
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