Glaze ice
Encyclopedia
Glaze ice or simply glaze is a smooth, transparent and homogenous
ice
coating occurring when freezing rain
or drizzle
hits a surface. It is similar in appearance to clear ice
, which forms from supercooled
water
droplets. It is a relatively common occurrence in temperate climates in the winter when precipitation form in warm air aloft and fall into below freezing temperature at the surface.
When the freezing rain or drizzle is light and not prolonged, the ice formed is thin. It usually causes only minor damage, relieving trees of their dead branches etc. When large quantities accumulate however, it is one of the most dangerous types of winter hazard. When the ice layer exceeds 0.2 inch (0.508 cm), tree limbs with branches heavily coated in ice can break off under the enormous weight and fall onto power lines. Windy conditions, when present, will exacerbate the damage. Power lines coated with ice become extremely heavy, causing support poles, insulators and lines to break. 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 it conforms to the shape of the ground, or object such as a tree branch or car it forms on, it is often difficult to notice until it is too late to react.
Glaze ice from freezing rain on a large scale causes effects on plants that 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.
Glaze ice from freezing rain is also an extreme hazard to aircraft, as it causes very rapid structural icing. Most helicopters and small airplanes lack the necessary deicing
equipment to fly in freezing rain of any intensity, and heavy icing can overwhelm even the most sophisticated deicing systems on large airplanes. Icing can dramatically increase an aircraft's weight, and by changing the shape of its airfoils also reduce lift and increase drag. All three factors increase stalling speed and reduce aircraft performance, making it very difficult to climb or even maintain level altitude. Icing is most easily evaded by moving into warmer air — under most conditions, this requires aircraft to descend, which can usually be done safely and easily even with a moderate accumulation of structural ice. However, freezing rain is accompanied by a temperature inversion aloft, meaning that aircraft actually need to climb to move into warmer air — a potentially difficult and dangerous task with even a small amount of ice accumulation.
It is also dangerous to ships owing to the increase in weight when ice forms on the superstructure. It may destabilise a vessel and cause it to overturn, especially in rough seas.
and northern parts of New York
and New England
in the North American ice storm of 1998
. .
Another example of the effect of glaze ice occurred during a freezing rain event during the unusually severe winter of 2009–2010 in the United Kingdom
. Heavy snow had fallen over much of the country in late December and early January. By the second week of January, many of the roads and pavements had been cleared by local councils due to the use of rock salt gritting. However, during the early hours of 12 January a wet front moved across the country causing freezing rain and heavy ice glaze, particularly in the South and West Yorkshire
areas of Northern England (crucially, this rainfall had stopped before first light). When the local population prepared to set out for work and school, they saw from their windows what appeared to be clear roads and pavements but which were in fact treacherous sheets of black ice
. Cars and buses almost immediately encounted extreme difficulty, and emergency services were called to dozens of accidents. Pedestrians in the village of Holmfirth
found the only safe way to proceed was to crawl on all fours. Accident and emergency units at hospitals in the Sheffield
, Rotherham
, and Barnsley
areas found themselves inundated by people with broken bones, fractures, and sprains, and many schools were closed as it was judged unsafe for pupils to attempt to make their way there.
On December 25, 2010, freezing rain fell on Moscow
and vicinity. The glaze ice accumulation caused a number of accidents and power outages, of which the most serious was damage caused to two power lines feeding Domodedovo Airport, causing a complete blackout of the airport and express railway that connected it to the city. As a result, the airport was shut down and hundreds of passengers were stranded inside, with taxi drivers charging up to 10,000 rubles
(USD 330) for a one-hour drive to the city.
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 (104.6 km) southeast of O'Hare. As the plane circled, the freezing rain formed a ridge of glaze 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, all passengers and crew were killed.
Homogeneous (chemistry)
A substance that is uniform in composition is a definition of homogeneous. This is in contrast to a substance that is heterogeneous.The definition of homogeneous strongly depends on the context used. In Chemistry, a homogeneous suspension of material means that when dividing the volume in half, the...
ice
Ice
Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...
coating occurring when freezing rain
Freezing rain
Freezing rain is the name given to rain that falls when surface temperatures are below freezing. The raindrops become supercooled while passing through a sub-freezing layer of air, many hundred feet , just above the surface, and then freeze upon impact with any object they encounter. The resulting...
or drizzle
Freezing drizzle
Freezing drizzle is drizzle that freezes on contact with the ground or an object at or near the surface. Its METAR code is FZDZ. When freezing drizzle accumulates on land it creates an icy layer of glaze...
hits a surface. It is similar in appearance to clear ice
Clear ice
Clear ice refers to a solid precipitation which forms when air temperature is between 0 °C and -3 °C and there are supercooled, relatively large drops of water...
, which forms from supercooled
Supercooling
Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid....
water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
droplets. It is a relatively common occurrence in temperate climates in the winter when precipitation form in warm air aloft and fall into below freezing temperature at the surface.
Effects
Glaze ice from freezing rain on a large scale causes effects on plants that 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.
Glaze ice from freezing rain is also an extreme hazard to aircraft, as it causes very rapid structural icing. Most helicopters and small airplanes lack the necessary deicing
Deicing
For snow and ice control on roadways and similar facilities, see Snow removalDe-icing is defined as removal of snow, ice or frost from a surface...
equipment to fly in freezing rain of any intensity, and heavy icing can overwhelm even the most sophisticated deicing systems on large airplanes. Icing can dramatically increase an aircraft's weight, and by changing the shape of its airfoils also reduce lift and increase drag. All three factors increase stalling speed and reduce aircraft performance, making it very difficult to climb or even maintain level altitude. Icing is most easily evaded by moving into warmer air — under most conditions, this requires aircraft to descend, which can usually be done safely and easily even with a moderate accumulation of structural ice. However, freezing rain is accompanied by a temperature inversion aloft, meaning that aircraft actually need to climb to move into warmer air — a potentially difficult and dangerous task with even a small amount of ice accumulation.
It is also dangerous to ships owing to the increase in weight when ice forms on the superstructure. It may destabilise a vessel and cause it to overturn, especially in rough seas.
Examples of damages
In February 1994, a severe ice storm caused over $1 billion in damage in the Southern United States, primarily in Mississippi, Tennessee, and Alabama. One particularly severe ice storm struck eastern CanadaCanada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and northern parts of New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
and New England
New England
New England is a region in the northeastern corner of the United States consisting of the six states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut...
in the North American ice storm of 1998
North American ice storm of 1998
The North American ice storm of 1998 was a massive combination of five smaller successive ice storms which combined to strike a relatively narrow swath of land from eastern Ontario to southern Quebec to Nova Scotia in Canada, and bordering areas from northern New York to central Maine in the...
. .
Another example of the effect of glaze ice occurred during a freezing rain event during the unusually severe winter of 2009–2010 in the United Kingdom
Winter of 2009–2010 in the United Kingdom
The winter of 2009–2010 in the United Kingdom was a meteorological event that started on 16 December 2009, as part of the severe winter weather in Europe. January 2010 was provisionally the coldest January since 1987 across the country...
. Heavy snow had fallen over much of the country in late December and early January. By the second week of January, many of the roads and pavements had been cleared by local councils due to the use of rock salt gritting. However, during the early hours of 12 January a wet front moved across the country causing freezing rain and heavy ice glaze, particularly in the South and West Yorkshire
Yorkshire
Yorkshire is a historic county of northern England and the largest in the United Kingdom. Because of its great size in comparison to other English counties, functions have been increasingly undertaken over time by its subdivisions, which have also been subject to periodic reform...
areas of Northern England (crucially, this rainfall had stopped before first light). When the local population prepared to set out for work and school, they saw from their windows what appeared to be clear roads and pavements but which were in fact treacherous sheets of black ice
Black ice
Black ice, sometimes called glare ice or clear ice, refers to a thin coating of glazed ice on a surface.While not truly black, it is virtually transparent, allowing black asphalt/macadam roadways to be seen through it, hence the term "black ice"...
. Cars and buses almost immediately encounted extreme difficulty, and emergency services were called to dozens of accidents. Pedestrians in the village of Holmfirth
Holmfirth
Holmfirth is a small town located on the A6024 Woodhead Road in the Holme Valley, within the Metropolitan Borough of Kirklees, West Yorkshire, England. Centred upon the confluence of the Holme and Ribble rivers, Holmfirth is south of Huddersfield and from Glossop. It mostly consists of...
found the only safe way to proceed was to crawl on all fours. Accident and emergency units at hospitals in the Sheffield
Sheffield
Sheffield is a city and metropolitan borough of South Yorkshire, England. Its name derives from the River Sheaf, which runs through the city. Historically a part of the West Riding of Yorkshire, and with some of its southern suburbs annexed from Derbyshire, the city has grown from its largely...
, Rotherham
Rotherham
Rotherham is a town in South Yorkshire, England. It lies on the River Don, at its confluence with the River Rother, between Sheffield and Doncaster. Rotherham, at from Sheffield City Centre, is surrounded by several smaller settlements, which together form the wider Metropolitan Borough of...
, and Barnsley
Barnsley
Barnsley is a town in South Yorkshire, England. It lies on the River Dearne, north of the city of Sheffield, south of Leeds and west of Doncaster. Barnsley is surrounded by several smaller settlements which together form the Metropolitan Borough of Barnsley, of which Barnsley is the largest and...
areas found themselves inundated by people with broken bones, fractures, and sprains, and many schools were closed as it was judged unsafe for pupils to attempt to make their way there.
On December 25, 2010, freezing rain fell on Moscow
Moscow
Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...
and vicinity. The glaze ice accumulation caused a number of accidents and power outages, of which the most serious was damage caused to two power lines feeding Domodedovo Airport, causing a complete blackout of the airport and express railway that connected it to the city. As a result, the airport was shut down and hundreds of passengers were stranded inside, with taxi drivers charging up to 10,000 rubles
Russian ruble
The ruble or rouble is the currency of the Russian Federation and the two partially recognized republics of Abkhazia and South Ossetia. Formerly, the ruble was also the currency of the Russian Empire and the Soviet Union prior to their breakups. Belarus and Transnistria also use currencies with...
(USD 330) for a one-hour drive to the city.
In 1994, American Eagle Flight 4184
American Eagle Flight 4184
American Eagle Flight 4184 was an American Eagle ATR 72 that crashed after flying into unknown icing conditions on October 31, 1994. Control was lost and all aboard were killed.-History:...
encountered heavy air traffic and poor weather that postponed the arrival of this flight at Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
's O'Hare International Airport
O'Hare International Airport
Chicago O'Hare International Airport , also known as O'Hare Airport, O'Hare Field, Chicago Airport, Chicago International Airport, or simply O'Hare, is a major airport located in the northwestern-most corner of Chicago, Illinois, United States, northwest of the Chicago Loop...
, where it was to have landed en route from Indianapolis, Indiana
Indianapolis, Indiana
Indianapolis is the capital of the U.S. state of Indiana, and the county seat of Marion County, Indiana. As of the 2010 United States Census, the city's population is 839,489. It is by far Indiana's largest city and, as of the 2010 U.S...
. The ATR-72, a twin-engine turboprop carrying 68 people, entered a holding pattern 65 miles (104.6 km) southeast of O'Hare. As the plane circled, the freezing rain formed a ridge of glaze 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, all passengers and crew were killed.
See also
- Black iceBlack iceBlack ice, sometimes called glare ice or clear ice, refers to a thin coating of glazed ice on a surface.While not truly black, it is virtually transparent, allowing black asphalt/macadam roadways to be seen through it, hence the term "black ice"...
- Clear iceClear iceClear ice refers to a solid precipitation which forms when air temperature is between 0 °C and -3 °C and there are supercooled, relatively large drops of water...
- Hoar frost
- Ice stormIce stormAn ice storm is a type of winter storm characterized by freezing rain, also known as a glaze event or in some parts of the United States as a silver thaw. The U.S. National Weather Service defines an ice storm as a storm which results in the accumulation of at least of ice on exposed surfaces...
- Rime ice
- VerglasVerglasVerglas may refer to:* Verglas Music, a record label which has released works such as Jabberwocky, a 1999 progressive rock album* Verglas, a climbing term referring to a thin coating of glaze ice on rock ....
External links
- Weather Glossary, G. The Weather Channel