Black ice

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Black ice on a road in Germany 2023-01-19 Plotzliches Glatteis und gefrorene Pfutzen in Tauberbischofsheim.jpg
Black ice on a road in Germany

Black ice, sometimes called clear ice, is a coating of glaze ice on a surface, for example on streets or on lakes. The ice itself is not black, but visually transparent, allowing the often black road below to be seen through it and light to be transmitted. The typically low levels of noticeable ice pellets, snow, or sleet surrounding black ice means that areas of the ice are often next to invisible to drivers or people walking on it. Thus, there is a risk of slippage and subsequent accident due to the unexpected loss of traction.

Contents

Definitions

The term black ice in the United States is defined by the National Weather Service as "patchy ice on roadways or other transportation surfaces that cannot easily be seen. It is often clear (not white) with the black road surface visible underneath. It is most prevalent during the early morning hours, especially after snowmelt on the roadways has a chance to refreeze overnight when the temperature drops below freezing. Black ice can also form when roadways are slick from rain and temperatures drop below freezing overnight." [1]

The World Meteorological Organization definitions of black ice are: [2] [3]

Formation

On roads and pavements

The American Meteorological Society Glossary of Meteorology includes the definition of black ice as "a thin sheet of ice, relatively dark in appearance, [that] may form when light rain or drizzle falls on a road surface that is at a temperature below 0 °C (32 °F)." [4] Because it represents only a thin accumulation, black ice is highly transparent and thus difficult to see compared with snow, frozen slush, or thicker ice layers. In addition, it is often interleaved with wet pavement, which is nearly identical in appearance.

Warning sign for icy pavement in Quebec, Canada Panneau routier Quebec gel au sol - Gaspe.jpg
Warning sign for icy pavement in Quebec, Canada

This condition makes driving, cycling or walking on affected surfaces extremely dangerous. Deicing with salt (sodium chloride) is effective down to temperatures of about −18 °C (0 °F). Other compounds such as magnesium chloride or calcium chloride have been used for extremely cold temperatures since the freezing-point depression of their solutions is lower.

At lower temperatures (below −18 °C (0 °F)), black ice can form on roadways when the moisture from automobile exhaust, such as motorcycles and cars, condenses on the road surface. [5]

Such conditions caused multiple accidents in Minnesota when the temperatures dipped below that point for a prolonged period of time in mid-December 2008. [6] Salt's ineffectiveness at melting ice at these temperatures compounds the problem. Black ice may form even when the ambient temperature is several degrees above the freezing point of water 0 °C (32 °F), if the air warms suddenly after a prolonged cold spell that has left the surface of the roadway well below the freezing point of water.

On December 1, 2013, heavy post-Thanksgiving weekend traffic encountered black ice on the westbound I-290 expressway in Worcester, Massachusetts. A chain reaction series of crashes resulted, involving three tractor-trailers and over 60 other vehicles. The ice formed suddenly on a long downward slope, surprising drivers coming over the crest of a hill, who could not see crashed vehicles ahead until it was too late to stop on the slick pavement. [7]

On February 11, 2021, icing in Dallas and Fort Worth, Texas, contributed to a crash on I-35W which authorities called a "mass casualty event". Over 100 cars were involved in the pileup and multiple fatalities were reported. [8]

On bridges

Warning sign for bridge on US highway Icyroadbridge.JPG
Warning sign for bridge on US highway

Bridges and overpasses can be especially dangerous. Black ice forms first on bridges and overpasses because air can circulate both above and below the surface of the elevated roadway when the ambient temperature drops, causing the pavement temperature on the bridge to fall rapidly. [9]

Case study in Minnesota

The I-35W Mississippi River bridge seen from below in 2006 I-35W Bridge - April, 2006.jpg
The I-35W Mississippi River bridge seen from below in 2006

The I-35W Mississippi River bridge in Minneapolis, Minnesota, was well known for its black ice before it collapsed in 2007 into the Mississippi River. It had caused several pileups during its 40-year life. On December 19, 1985, the temperature reached −34 °C (−29 °F). Cars crossing the bridge experienced black ice and there was a massive pile up of crashed vehicles on the bridge on the northbound side. In February and in December 1996, the bridge was identified as the single most treacherous cold-weather spot in the local freeway system, because of the almost frictionless thin layer of black ice that regularly formed when temperatures dropped below freezing. The bridge's proximity to Saint Anthony Falls contributed significantly to the icing problem and the site was noted for frequent spinouts and collisions. [10] [11]

By January 1999, Mn/DOT began testing magnesium chloride solutions and a mixture of magnesium chloride and a corn-processing byproduct to see whether either would reduce the black ice that appeared on the bridge during the winter months. [12] In October 1999, the state embedded temperature-activated nozzles in the bridge deck to spray the bridge with potassium acetate solution to keep the area free of winter black ice. [13] [14] The system came into operation in 2000. [15] [16]

On water

Black ice on a canal in the Netherlands Black ice river.jpg
Black ice on a canal in the Netherlands

When the temperature is below freezing and the wind is calm, such as under a high atmospheric pressure at night in the fall, a thin layer of ice will form over open water of a lake. If the depth of the body of water is large enough, its color is black and can be seen through the ice, thus the name black ice. On lakes, black ice is also commonly overlain by white ice formed from refrozen snow or slush towards spring. [17] Black ice transmits more light than white ice [18] which can be important for primary producers in lakes, such as phytoplankton. Black ice has a higher bearing capacity than white ice [17] which is important to consider for ice safety reasons when doing recreational activities on lakes, such as ice skating and ice fishing.

Ice can also be formed by seawater spray and water vapour freezing upon contact with a vessel's superstructure when temperature is low enough. Ice formed in this manner is known as rime. [19] As the formation progress, the aboveboard weight of the vessel increases and may ultimately cause capsizing. Furthermore, rime ice may impede the correct functioning of important navigational instruments on board, such as radar or radio installations. Different strategies for the removal of such ice are employed: chipping away the ice or even using fire hoses in an attempt to remove the ice.

In mountains

Black ice is a significant hazard for climbers and scramblers. Cold weather is common at high altitudes, and black ice quickly forms on rock surfaces. Loss of traction is as sudden and unexpected as on a pavement or road, but can be dangerous if the rock is in an exposed position with a drop below. An ice-axe and crampons are essential use in such circumstances as they will help to prevent a fall, and a belay rope will help to arrest a fall.

See also

Related Research Articles

<span class="mw-page-title-main">Frost</span> Coating or deposit of ice

Frost is a thin layer of ice on a solid surface, which forms from water vapor that deposits onto a freezing surface. Frost forms when the air contains more water vapor than it can normally hold at a specific temperature. The process is similar to the formation of dew, except it occurs below the freezing point of water typically without crossing through a liquid state.

<span class="mw-page-title-main">Ice</span> Frozen water: the solid state of water

Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 °C, 32 °F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally occurring crystalline inorganic solid with an ordered structure, ice is considered to be a mineral. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color.

<span class="mw-page-title-main">Snow</span> Precipitation in the form of ice crystal flakes

Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size, precipitate and accumulate on surfaces, then metamorphose in place, and ultimately melt, slide or sublimate away.

<span class="mw-page-title-main">Sodium chloride</span> Chemical compound with formula NaCl

Sodium chloride, commonly known as edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chlorine ions. It is transparent or translucent, brittle, hygroscopic, and occurs as the mineral halite. In its edible form, it is commonly used as a condiment and food preservative. Large quantities of sodium chloride are used in many industrial processes, and it is a major source of sodium and chlorine compounds used as feedstocks for further chemical syntheses. Another major application of sodium chloride is deicing of roadways in sub-freezing weather.

Freezing rain is rain maintained at temperatures below freezing by the ambient air mass that causes freezing on contact with surfaces. Unlike a mixture of rain and snow or ice pellets, freezing rain is made entirely of liquid droplets. The raindrops become supercooled while passing through a sub-freezing layer of air hundreds of meters above the ground, and then freeze upon impact with any surface they encounter, including the ground, trees, electrical wires, aircraft, and automobiles. The resulting ice, called glaze ice, can accumulate to a thickness of several centimeters and cover all exposed surfaces. The METAR code for freezing rain is FZRA.

<span class="mw-page-title-main">Snow removal</span> Job of removing snow

Snow removal or snow clearing is the job of removing snow after a snowfall to make travel easier and safer. This is done both by individual households and by governments, institutions, and commercial businesses.

<span class="mw-page-title-main">Deicing</span> Process of removing ice, snow, or frost from a surface

Deicing is the process of removing snow, ice or frost from a surface. Anti-icing is the application of chemicals that not only deice but also remain on a surface and continue to delay the reformation of ice for a certain period of time, or prevent adhesion of ice to make mechanical removal easier.

<span class="mw-page-title-main">Rime ice</span> Granular whitish deposit of ice formed by freezing fog

Rime ice forms when supercooled water droplets freeze onto surfaces. In the atmosphere, there are three basic types of rime ice:

<span class="mw-page-title-main">Ice accretion indicator</span>

The ice accretion indicator is an L-shaped piece of aluminium 38 cm (15 in) long by 4 to 5 cm wide. It is used to indicate the formation of ice, frost or the presence of freezing rain or freezing drizzle.

<span class="mw-page-title-main">Icing (aeronautics)</span> Formation of water ice on aircraft surfaces

In aeronautics, icing is the formation of water ice on an aircraft. Icing has resulted in numerous fatal accidents in aviation history. Ice accretion and accumulation can affect the external surfaces of an aircraft – in which case it is referred to as airframe icing – or the engine, resulting in carburetor icing, air inlet icing or more generically engine icing. These phenomena may possibly but do not necessarily occur together.

<span class="mw-page-title-main">Atmospheric icing</span> Weather condition in which water droplets freeze onto objects they come in contact with

Atmospheric icing occurs in the atmosphere when water droplets suspended in air freeze on objects they come in contact with. It is not the same as freezing rain, which is caused directly by precipitation.

<span class="mw-page-title-main">Interstate 35W (Texas)</span> Highway in Texas

Interstate 35W (I-35W), a north–south Interstate Highway, is the western half of I-35 where it splits to serve the Dallas–Fort Worth metropolitan area. I-35 splits into two branch routes, I-35W and I-35E, at Hillsboro. I-35W runs north for 85.2 miles (137.1 km), carrying its own separate sequence of exit numbers. It runs through Fort Worth before rejoining with I-35E to reform I-35 in Denton. It is the more direct route for long-distance expressway traffic, as is noted on signs on I-35 leading into the I-35W/I-35E splits. During the 1970s, billboards existed on I-35 encouraging travelers to take the faster and shorter I-35W route.

<span class="mw-page-title-main">Anchor ice</span> Submerged ice anchored to a river bottom or seafloor

Anchor ice is defined by the World Meteorological Organization as "submerged ice attached or anchored to the bottom, irrespective of the nature of its formation". It may also be called bottom-fast ice. Anchor ice is most commonly observed in fast-flowing rivers during periods of extreme cold, at the mouths of rivers flowing into very cold seawater, in the shallow sub or intertidal during or after storms when the air temperature is below the freezing point of the water, and the subtidal in the Antarctic along ice shelves or near floating glacier tongues, and in shallow lakes.

In ground deicing of aircraft, aircraft deicing fluid (ADF), aircraft deicer and anti-icer fluid (ADAF) or aircraft anti-icing fluid (AAF) are commonly used for both commercial and general aviation. Environmental concerns include increased salinity of groundwater where de-icing fluids are discharged into soil, and toxicity to humans and other mammals.

<span class="mw-page-title-main">I-35W Mississippi River bridge</span> Bridge in Minneapolis, Minn., US, that collapsed in 2007

The I-35W Mississippi River bridge was an eight-lane, steel truss arch bridge that carried Interstate 35W across the Mississippi River one-half mile downstream from the Saint Anthony Falls in Minneapolis, Minnesota, United States. The bridge opened in 1967, and was Minnesota's third busiest, carrying 140,000 vehicles daily. After only 39 years in service, it experienced a catastrophic failure during the evening rush hour on August 1, 2007, killing 13 people and injuring 145. The National Transportation Safety Board (NTSB) cited a design flaw as the likely cause of the collapse, noting that an excessively thin gusset plate ripped along a line of rivets. Additional weight on the bridge at the time of failure was also cited by the NTSB as a contributing factor.

Freezing drizzle is drizzle that freezes on contact with the ground or an object at or near the surface. Its METAR code is FZDZ.

<span class="mw-page-title-main">Winter service vehicle</span> Vehicle used to clear snow and ice

A winter service vehicle (WSV), or snow removal vehicle, is a vehicle specially designed or adapted to clear thoroughfares of ice and snow. Winter service vehicles are usually based on a dump truck chassis, with adaptations allowing them to carry specially designed snow removal equipment. Many authorities also use smaller vehicles on sidewalks, footpaths, and cycleways. Road maintenance agencies and contractors in temperate or polar areas often own several winter service vehicles, using them to keep the roads clear of snow and ice and safe for driving during winter. Airports use winter service vehicles to keep both aircraft surfaces, and runways and taxiways free of snow and ice, which, besides endangering aircraft takeoff and landing, can interfere with the aerodynamics of the craft.

<span class="mw-page-title-main">Graupel</span> Precipitation that forms when supercooled droplets of water freeze on a falling snowflake

Graupel, also called soft hail or snow pellets, is precipitation that forms when supercooled water droplets in air are collected and freeze on falling snowflakes, forming 2–5 mm (0.08–0.20 in) balls of crisp, opaque rime.

<span class="mw-page-title-main">Glaze (ice)</span> Coating of ice on objects

Glaze or glaze ice, also called glazed frost or verglas, is a smooth, transparent and homogeneous 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 forms in warm air aloft and falls into below-freezing temperature at the surface.

Freezing or frost occurs when the air temperature falls below the freezing point of water. This is usually measured at the height of 1.2 metres above the ground surface.

References

  1. ↑ National Weather Service. "Ice Storms" . Retrieved February 13, 2021.
  2. ↑ International Cloud Atlas (WMO-No. 407), online edition. "Black Ice". UNTERM. Retrieved February 14, 2021.{{cite web}}: CS1 maint: numeric names: authors list (link)
  3. ↑ International Meteorological Vocabulary, WMO - No. 182. "Black Ice". UNTERM. Retrieved February 14, 2021.{{cite web}}: CS1 maint: numeric names: authors list (link)
  4. ↑ "AMS Glossary: Black ice". Amsglossary.allenpress.com. Retrieved November 28, 2013.
  5. ↑ "Is there really such a thing as black ice?". 9 July 2002. Retrieved December 22, 2008.
  6. ↑ "Black ice causes treacherous driving conditions in metro". KARE 11 TV. Retrieved December 22, 2008.[ permanent dead link ]
  7. ↑ Abel, David (December 2, 2013). "On busy travel day, black ice led to massive pileup in Worcester". Boston Globe . Retrieved December 3, 2013.
  8. ↑ Rachel Treisman (February 11, 2021). "At least 5 people dead after Texas Interstate Crash involving at least 75 vehicles". NPR. Retrieved February 11, 2021.
  9. ↑ Jeffrey Selingo (December 13, 2001), "How it works: Black ice", The New York Times
  10. ↑ Blake, Laurie. (February 3, 1996) Star Tribune February deep freeze. Black ice makes I-35W bridge treacherous. Section: news; Page 10A.
  11. ↑ von Sternberg, Bob. (December 27, 1996) Star Tribune Minnesota is one big deep freeze. What is the sound of a cold record shattering? It's the sound of silence from dead motors, of crumpling metal on icy roads, of resigned grumbling. But take heart — it will warm up. Section News; page 1A.
  12. ↑ Blake, Laurie. (January 21, 1999) Star Tribune State hopes to speed up north-metro lane project. But it clashes with Met Council over whether addition to interstate should be for car pools. Section news; Page 2B.
  13. ↑ Blake, Laurie. (October 19, 1999) Star Tribune I-35W bridge getting de-icer system. Unit will target ice before it can form. Section news; Page 1A.
  14. ↑ "I-35W & Mississippi River Bridge Anti-Icing Project" (PDF). Archived from the original (PDF) on October 5, 2011.
  15. ↑ Blake, Laurie. (January 13, 2000) Star Tribune Met Council will survey our citizens' travel habits. Study will include trip numbers and times, speed of drivers and waits at ramp meters. Section news; Page 2B.
  16. ↑ Blake, Laurie. (February 3, 2000) Star Tribune Richfield may face traffic challenges; How will I-494 accommodate Best Buy's 5,000 commuters? Section news, page 2B.
  17. 1 2 Weyhenmeyer, Gesa A.; Obertegger, Ulrike; Rudebeck, Hugo; Jakobsson, Ellinor; Jansen, Joachim; Zdorovennova, Galina; Bansal, Sheel; Block, Benjamin D.; Carey, Cayelan C.; Doubek, Jonathan P.; Dugan, Hilary; Erina, Oxana; Fedorova, Irina; Fischer, Janet M.; Grinberga, Laura (2022-08-25). "Towards critical white ice conditions in lakes under global warming". Nature Communications. 13 (1): 4974. Bibcode:2022NatCo..13.4974W. doi:10.1038/s41467-022-32633-1. hdl: 10449/76535 . ISSN   2041-1723. PMC   9411540 . PMID   36008420.
  18. ↑ Bolsenga, S. J.; Vanderploeg, H. A. (1992-10-01). "Estimating photosynthetically available radiation into open and ice-covered freshwater lakes from surface characteristics; a high transmittance case study". Hydrobiologia. 243 (1): 95–104. Bibcode:1992HyBio.243...95B. doi:10.1007/BF00007024. ISSN   1573-5117.
  19. ↑ National Weather Service. "Rime ice". NOAA . Retrieved November 28, 2013.
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