Freezing Rain is a type of precipitation that begins as snow at higher altitude, falling from a cloud towards earth, melts completely on its way down while passing through a layer of air above freezing temperature, and then encounters a layer below freezing at lower level to become supercooled. This water will then freeze upon impact of any object it then encounters.^[1] The ice can accumulate to a thickness of several centimetres, called glaze ice. The METAR code for freezing rain is FZRA.^[2] (see freezing drizzle for another way of forming ice accretion) For other uses, see Snow (disambiguation). ... For other uses, see Cloud (disambiguation). ... Supercool redirects here. ... In physics and chemistry, freezing is the process whereby a liquid turns to a solid. ... A centimetre (American spelling centimeter, symbol cm) is a unit of length that is equal to one hundredth of a metre, the current SI base unit of length. ... Glaze ice over a playground after an icestorm Glaze ice is a smooth, transparent and homogenous ice coating occurring when freezing rain or drizzle hit a surface. ... METAR (for METeorological Aerodrome Report) is a format for reporting weather information. ... Freezing drizzle is drizzle that freezes on contact with the ground or an object at or near the surface. ... In atmospheric science, accretion stands for growth of a precipitation particle by the collision of an ice crystal or snowflake with a supercooled liquid droplet that freezes upon impact. ...

Mechanism

Detail of ice clad leaves

Usually freezing rain is associated with the approach of a warm front when cold air, at or below freezing temperature, is trapped in the lower levels of the atmosphere as warmth streams in aloft.^[3] This happens, for instance, when a low pressure system moves from the Mississippi River Valley toward the Appalachian mountains and the Saint Lawrence River Valley of North America, in the cold season, and there is a strong high pressure system sitting further East. The warm air from the Gulf of Mexico is often the fuel for freezing precipitation. Image File history File linksMetadata Size of this preview: 400 × 600 pixelsFull resolution (800 × 1200 pixel, file size: 774 KB, MIME type: image/jpeg) Template:FPC File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Freezing rain User:Rklawton... Image File history File linksMetadata Size of this preview: 400 × 600 pixelsFull resolution (800 × 1200 pixel, file size: 774 KB, MIME type: image/jpeg) Template:FPC File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Freezing rain User:Rklawton... Illustration of a warm front A warm front is defined as the leading edge of a mass of warm air. ... For the river in Canada, see Mississippi River (Ontario). ... The Appalachian Mountains are a vast system of mountains in eastern North America. ... a broat veiew of the St LAwrence River, with a Quebec City on a background The Saint Lawrence River (In French: fleuve Saint-Laurent) is a large south west-to-north east flowing river in the middle latitudes of North America, connecting the Great Lakes with the Atlantic Ocean. ... North America North America is a continent[1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... Gulf of Mexico in 3D perspective. ...

The warm air is then forced aloft where it dramatically alters the temperature in the middle layer, around 800 mbar (800 hPa). If the advection is strong enough to warm a thin layer several degrees above 0 °C for a brief period or a larger one slightly above 0 °C for a long period, the falling snow into this layer will melt and become rain droplets. These will freeze on contact when they hit the ground, which is still at or below 0 °C.
For other uses, see Temperature (disambiguation). ... A millibar (mbar, also mb) is 1/1000th of a bar, a unit for measurement of pressure. ... For other uses, see Pascal. ... Advection is the transport of a conserved scalar quantity that is transported in a vector field. ... For other uses, see Snow (disambiguation). ... This article is about precipitation. ...

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Image File history File links Question_book-3. ...

Observations

Echoes at 1.5 km altitude at the top with strong contamination from the brightband (yellows). The vertical cut at the bottom show that this strong return is only above ground (Source: Environment Canada).

Surface observations by manned or automatic stations are the only direct confirmation of freezing rain. One can never see directly freezing rain, rain or snow on weather radars, Doppler or conventional. However, it is possible to estimate the area covered by freezing rain with radars indirectly. Image File history File links Radar-bright-band. ... Image File history File links Radar-bright-band. ... Environment Canada is the department of the government of Canada with responsibility for coordinating environmental policies and programs as well as preserving and enhancing the natural environment and conservation of wildlife. ... Weather radar in Norman, Oklahoma with rainshaft (Source: NOAA) Environment Canada King City (CWKR) weather radar station. ... Doppler Effect Doppler radar uses the Doppler effect to measure the radial velocity of targets in the antennas directional beam. ... For other uses, see Radar (disambiguation). ...

The intensity of the radar echoes (reflectivity) is proportional to the form (water or ice) of the precipitation and its diameter. In fact, rain has much stronger reflective power than snow but its diameter is much smaller. So the reflectivity of rain coming from melted snow is only slightly higher. However, in the layer where the snow is melting, the wet flakes still have a large diameter and are coated with water so the returns to the radar is much stronger. In optics, reflectivity is the reflectance (the ratio of reflected power to incident power, generally expressed in decibels or percentage) at the surface of a material so thick that the reflectance does not change with increasing thickness; , the intrinsic reflectance of the surface, irrespective of other parameters such as the...

The presence of this brightband indicates that there is a warm layer above ground where snow melts. This could be producing rain on the ground or the possibility of freezing rain if the temperature is below freezing. This artifact can be located, like on the image at left, with a cross-section through radar data. The height and slope of the brightband will give clues to the extent of the region where melting occurs. Then it is possible to associate this clue with surface observations and numerical models prediction to produce output such as the ones seen on television weather programs that divide radar echoes into rain, mixed and snow precipitations. Weather radar in Norman, Oklahoma with rainshaft (Source: NOAA) Environment Canada King City (CWKR) weather radar station. ... In natural science and signal processing, an artifact is any perceived distortion or other data error caused by the instrument of observation. ...

Effects

Iced power lines threaten power outage to many

Ice glaze on crabapple

Freezing rain often causes major power outages. Power lines coated with ice become extremely heavy, causing support poles, insulators and lines to break. Tree limbs with branches heavily coated in ice also can break off under the enormous weight and fall onto power lines. The ice that forms on roadways makes vehicle travel dangerous. Unlike snow, wet ice provides almost no traction, and vehicles will slide even on gentle slopes. Because freezing rain does not hit the ground as an ice pellet and is still a rain droplet when it makes contact with the ground, the freezing rain conforms to the shape of the ground, making one thick layer of ice, often called glaze. Because sleet is in pellet form it can be easily moved around, unlike freezing rain which is a continuous layer of ice and cannot be moved around. Image File history File linksMetadata Size of this preview: 400 × 600 pixelsFull resolution (800 × 1200 pixel, file size: 827 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Freezing rain User:Rklawton/Galleries Metadata... Image File history File linksMetadata Size of this preview: 400 × 600 pixelsFull resolution (800 × 1200 pixel, file size: 827 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Freezing rain User:Rklawton/Galleries Metadata... Image File history File linksMetadata Size of this preview: 795 × 599 pixelsFull resolution (1524 × 1149 pixel, file size: 357 KB, MIME type: image/jpeg) Ice glaze on crabapple File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File linksMetadata Size of this preview: 795 × 599 pixelsFull resolution (1524 × 1149 pixel, file size: 357 KB, MIME type: image/jpeg) Ice glaze on crabapple File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... This article is about water ice. ... Sleet is a term used in a variety of ways to describe precipitation intermediate between rain and snow but distinct from hail. ...

Freezing rain and glaze measured on a large scale is called an ice storm. Effects on plants can be severe, as they cannot support the weight of the ice. Trees may snap as they are dormant and fragile during winter weather. Pine trees are also victims of ice storms as their needles will catch the ice, but not be able to support the weight. Ice storm could refer to: A type of winter storm characterized by freezing rain. ... This article is about water ice. ... Winter is one of the four seasons of temperate zones. ... This article is about water ice. ...

One particularly severe ice storm struck eastern Canada and northern parts of New York and New England in January of 1998; for details see 1998 Ice Storm. This article is about the state. ... This article is about the region in the United States of America. ... The 1998 Canada Ice Storm was a massive ice storm that struck eastern Canada and Northern New York in January 1998. ...

An severe ice storm caused over $1 billion in damage in the Southern United States in February 1994, primarily in Mississippi, Tennessee, and Alabama.

In 1994, American Eagle Flight 4184 encountered heavy air traffic and poor weather that postponed the arrival of this flight at Chicago's O'Hare International Airport, where it was to have landed en route from Indianapolis, Indiana. The ATR-72, a twin-engine turboprop carrying 68 people, entered a holding pattern 65 miles southeast of O'Hare. As the plane circled, freezing rain formed a ridge of ice on the upper surface of its wings, eventually causing the aircraft's autopilot to suddenly disconnect and the pilots to lose control. The ATR disintegrated on impact with a field below, killing everyone aboard. Year 1994 (MCMXCIV) The year 1994 was designated as the International Year of the Family and the International Year of the Sport and the Olympic Ideal by the United Nations. ... American Eagle Flight 4184 was a regional airline flight that crashed after flying into known icing conditions on October 31, 1994. ... Nickname: Motto: Urbs in Horto (Latin: City in a Garden), I Will Location in the Chicago metro area and Illinois Coordinates: , Country State Counties Cook, DuPage Settled 1770s Incorporated March 4, 1837 Government  - Mayor Richard M. Daley (D) Area  - City  234. ... OHare International Airport (IATA: ORD, ICAO: KORD, FAA LID: ORD) is an airport located in Chicago, Illinois, United States, 17 miles (27 km) northwest of the Chicago Loop. ... Indianapolis redirects here. ...

See also

• 1998 Ice Storm
• Freezing drizzle
• Hail
• Sleet
• Wintry showers

The 1998 Canada Ice Storm was a massive ice storm that struck eastern Canada and Northern New York in January 1998. ... Freezing drizzle is drizzle that freezes on contact with the ground or an object at or near the surface. ... This article is about the precipitation. ... Sleet is a term used in a variety of ways to describe precipitation intermediate between rain and snow but distinct from hail. ... Wintry showers is a somewhat informal meteorological term, used primarily in the United Kingdom, to refer to various mixtures of rain, freezing rain, sleet and snow. ...

References

Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 342nd day of the year (343rd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 342nd day of the year (343rd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 342nd day of the year (343rd in leap years) in the Gregorian calendar. ...

External links

• Canadian ice storm of 1998
• Climatology of freezing rain
• Video of Ice-storm