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Ice_fog

Ice fog is a meteorological phenomenon characterized by a suspension of numerous minute ice crystals in the air, which significantly reduces horizontal visibility at the Earth's surface to less than 1 km, often below 50 m.^[1] It occurs in very cold environments, generally below -20 °C and more typically below -30 °C, where water vapor—frequently originating from human activities such as combustion processes—condenses into supercooled droplets that freeze into tiny ice particles or deposits directly as ice without a prolonged liquid phase.^[1] These ice crystals, with diameters ranging from 2 to 30 μm and lacking well-defined crystalline shapes, distinguish ice fog from related phenomena like diamond dust, as they do not produce optical effects such as halos.^[1] Ice fog forms through nucleation processes, either homogeneous (in highly supersaturated air) or heterogeneous (on ice nuclei), often under calm, clear conditions with strong temperature inversions that trap moisture near the surface.^[2] In polar and subarctic regions, such as interior Alaska, northern Canada, and Antarctica, it is prevalent during winter months when low wind speeds and high relative humidity with respect to ice (RHi > 100%) promote the suspension of high concentrations of these particles, exceeding 1000 per liter.^[2] Natural sources like open water or vegetation can contribute, but anthropogenic emissions from vehicles, power plants, and heating systems are primary drivers in populated areas, exacerbating its frequency in urban settings like Fairbanks, Alaska.^[3] The impacts of ice fog are multifaceted, posing severe risks to aviation and transportation due to its shallow vertical extent—often limited to a few hundred meters—which can create illusions of clear conditions from above while obscuring the surface.^[4] It contributes to aircraft icing if supercooled elements are present and disrupts operations in Arctic regions, where increasing air traffic amplifies safety concerns.^[5] Environmentally, ice fog alters local climate by enhancing downward infrared radiation (up to 60 W m⁻²) and reducing surface albedo, while also trapping pollutants and affecting air quality in cold, stagnant air masses.^[2] Ongoing research emphasizes improved microphysical modeling and field observations to better predict and mitigate these effects amid climate change; recent studies, such as those in Fairbanks (as of 2023), show decreasing frequency potentially due to warming trends.^[2]^[6]

Definition and Characteristics

Definition

Ice fog is a meteorological phenomenon defined as a suspension of tiny ice crystals in the air at or near the Earth's surface, reducing horizontal visibility to less than 1 km. These ice crystals, typically ranging from 2 to 30 micrometers in diameter, form exclusively from ice particles without any liquid water content.^[7]^[5]^[8] Ice fog occurs only under extremely cold conditions, generally at temperatures below -30°C (-22°F), becoming more frequent and persistent as temperatures drop further, often below -40°C.^[7] This distinguishes it from freezing fog, which consists of supercooled liquid water droplets that freeze on contact with surfaces, and from diamond dust, a related but distinct occurrence of tiny falling ice crystals formed aloft rather than remaining suspended near the ground.^[9]^[10]^[2] The term "ice fog" entered meteorological literature in the mid-20th century, with early studies by researchers like Arnold Wexler in the 1930s and 1940s describing its characteristics in Arctic regions. It is also known regionally as "pogonip," a Shoshone Native American term referring to the "icy fog" or "white death" observed in western U.S. mountain valleys.^[5]^[11]

Physical Properties

Ice fog is composed of small ice crystals often in the form of droxtals (frozen droplets), irregular shapes, or small pristine crystals, lacking well-defined habits like large plates or columns, resulting from the direct deposition of water vapor onto ice nuclei. The ice water content is typically less than 0.05 g m⁻³.^[2] The crystals typically measure 2–30 micrometers in diameter, with concentrations varying from tens to over 1,000 per liter in intense events. This low mass concentration contributes to the fog's lightweight nature, enabling prolonged suspension in the atmosphere. Due to their small size and low density, the crystals remain aloft in calm winds below 2 m/s but dissipate rapidly when winds exceed this threshold or temperatures rise above critical freezing points.^[2]^[12]^[2] Optically, ice fog exhibits high scattering efficiency from its submicron to tens-of-micrometers particles, producing a diffuse bluish-white appearance. These properties arise from the crystals' interaction with visible light wavelengths, enhancing forward scattering while reducing overall transmittance.^[2] Thermodynamically, ice fog maintains stability in high-pressure anticyclonic systems where relative humidity approaches 100% with respect to ice and temperatures remain below -30°C, fostering supersaturation conditions that prevent rapid sublimation.^[2]

Formation Mechanisms

Atmospheric Conditions

Ice fog formation requires extremely low air temperatures, typically below -30°C, with optimal conditions occurring at -40°C or lower, where the saturation vapor pressure over ice is significantly reduced, facilitating the direct sublimation of water vapor into ice crystals.^[2] These cold conditions are often accompanied by strong surface-based temperature inversions, which trap the cold air near the ground and prevent vertical mixing, creating a stable layer usually 50-100 meters deep but sometimes extending up to 1 km. Such inversions, with temperature gradients of 10-30°C per 100 meters, are common in Arctic and subarctic regions during prolonged radiative cooling under clear skies.^[2] High relative humidity is essential, with the air needing to reach near-saturation with respect to ice (relative humidity over ice, RHi, approaching or exceeding 100%), and supersaturation (RHi > 105-110%), where ice crystals grow by vapor deposition from the surrounding supersaturated air.^[2] Moisture sources contributing to this humidity typically include open water bodies such as rivers or leads in sea ice, which release water vapor without significant heat, as well as anthropogenic emissions from combustion processes that can lead to nucleation. Over snow-covered ground, the surface remains cold and does not warm the air, allowing humidity to build steadily. Calm wind conditions, generally below 2 m/s (approximately 7 km/h) or nearly still, are critical for ice fog development, as they minimize turbulence that would otherwise disperse ice crystals and prevent their accumulation.^[2] These low winds often prevail within high-pressure systems, enhancing atmospheric stability and allowing the fog to form in a shallow layer near the surface. Ice fog can persist for hours to days, or even weeks during extended stable Arctic winter periods, due to the small size of ice crystals (resulting in low sedimentation rates) and the maintenance of inversion layers.^[2]

Nucleation Processes

Ice fog nucleation primarily occurs through heterogeneous processes, as homogeneous nucleation is rare and limited to extreme conditions of supersaturation below approximately -38°C, where supercooled water droplets freeze without nuclei. Heterogeneous nucleation, which occurs at the low temperatures typical of ice fog (below -30°C), primarily involves deposition nucleation, where water vapor directly transitions to ice on suitable particles. When supercooled droplets are present (e.g., in freezing fog), immersion freezing (nuclei within droplets initiate freezing) or contact freezing (collisions between droplets and ice nuclei) can also contribute. Common nuclei include soot from combustion, mineral dust, and anthropogenic particles such as vehicle exhaust or power plant emissions, which lower the energy barrier for ice formation compared to pure water.^[13]^[14] In regions with high anthropogenic activity, such as Fairbanks, Alaska, pollution from residential wood burning, diesel exhaust, and other combustion sources significantly enhances nucleation by providing abundant ice-nucleating particles (INPs), with concentrations often exceeding those in remote Arctic environments by orders of magnitude. For instance, during a 2022 ice fog event in Fairbanks, INP concentrations at -15°C, higher than in remote Arctic environments, with soot comprising about 30% of particles and dust around 44%, leading to a 58% reduction in INP concentrations as they activated into fog crystals. This anthropogenic influence increases ice fog frequency and persistence in urban valleys, where calm winds and inversions trap pollutants.^[15]^[13] Following nucleation, ice crystals in ice fog grow primarily through vapor deposition under ice-supersaturated conditions, as the absence of liquid water precludes riming. Crystal habits typically develop as platelike between -20°C and -40°C or columnar at colder temperatures below -40°C, influenced by the temperature-dependent vapor diffusion rates to different crystal faces. The Bergeron-Findeisen process, adapted to this all-ice environment, drives preferential growth by vapor diffusion from the ambient air to ice surfaces when the relative humidity with respect to ice exceeds 100%, depleting surrounding vapor and allowing larger crystals to dominate.^[16]^[14] The rate of mass growth by deposition for individual crystals follows the basic form \frac{dm}{dt} \propto (e - e_s), where m is crystal mass, e is the ambient vapor pressure, and e_s is the saturation vapor pressure over ice; a more detailed expression is \frac{dm}{dt} = 4\pi C D_v \frac{(e - e_s)}{R_v T} r, with C as the crystal capacitance, D_v the water vapor diffusion coefficient, R_v the gas constant for water vapor, T temperature, and r the crystal size parameter. For an ensemble, the total deposition rate is \frac{dM}{dt} = \sum N_i \frac{dm_i}{dt}, where N_i is the number of crystals of type i. This parameterization, derived from diffusion-limited growth theory, highlights how supersaturation drives rapid initial growth of small crystals in ice fog.^[14]^[14]

Geographical Occurrence

Polar and Arctic Regions

Ice fog is particularly prevalent in the Arctic regions, including the Canadian Archipelago and Siberia, as well as Antarctic coastal areas, where extreme cold allows for the formation of ice crystals in the atmosphere under temperatures routinely dropping below -40°C. In the Canadian Arctic, for instance, sites like Alert, Nunavut, experience ice fog during the polar night when prolonged darkness enhances radiative cooling, leading to supersaturation of available moisture. Siberian locations such as Verkhoyansk also see frequent occurrences, driven by similar cold, stable conditions over vast inland and coastal expanses. Antarctic coastal zones, including areas around Ross Island, exhibit ice fog in winter, though often influenced by nearby ice shelves and fast ice.^[14]^[17]^[18] The frequency of ice fog and diamond dust combined in these polar environments can reach up to 40% of winter observations in places like Alert, with ice fog alone occurring around 10% of the time, translating to approximately 20-25 days per year during the cold season from November to May, closely tied to the presence of sea ice leads and polynyas that provide localized moisture sources. These open water features within the pack ice release vapor through evaporation or sublimation, which then nucleates into ice crystals under the frigid conditions. Sublimating snow on the surface also contributes to the available water vapor, sustaining fog formation in low-wind environments. Katabatic winds, descending from ice sheets and flowing toward coastal areas, help distribute this moisture-laden air, exacerbating ice fog persistence over broader regions. In the Antarctic, coastal ice fog events are shorter-lived, typically 1-3 hours, but occur regularly in winter under stable inversions.^[14]^[19]^[5] Historical records from 1950s expeditions and observations at Arctic stations including Barrow and Eureka indicate that ice fog was a common winter phenomenon, often persisting for days under clear, calm conditions with temperatures below -40°C. These early datasets, gathered during international efforts like the International Geophysical Year preparations, highlighted ice fog's role in reducing visibility across remote polar expanses, with notable multi-day events documented in Alaska and Greenland. Post-2000 observations reveal a slight overall decrease in ice fog frequency due to Arctic warming, which raises minimum temperatures and disrupts the necessary cold thresholds; however, intensity appears to increase near melting sea ice edges, where enhanced open water from retreating ice provides more moisture for nucleation. This trend is evident in regions like the northern Canadian Archipelago, where post-2000 satellite and in situ data show localized spikes in fog events adjacent to polynyas.^[17]^[5]^[20]

Continental and Urban Areas

Ice fog manifests in continental and urban areas within subarctic climates, notably in interior Alaska around Fairbanks, central Canada near Yellowknife, and Siberian Russia at Yakutsk, where extreme cold and topographic features foster its development. These regions experience ice fog during prolonged periods of subzero temperatures, typically below -30°C, when local moisture sources such as open water or human activities condense into suspended ice crystals. Episodes have also been observed in the U.S. Midwest, such as Chicago, during rare extreme cold snaps when temperatures plummet below -30°F, though these are less frequent than in higher-latitude continental interiors.^[21]^[22]^[23] In urban environments, ice fog is amplified by anthropogenic emissions from vehicles, power plants, and industries, which serve as efficient ice nuclei and create hybrid "smog-ice fog" conditions by combining particulate pollution with ice crystals. For instance, in Fairbanks, a significant ice fog event in January 2017 persisted amid a multi-week cold spell with temperatures consistently below -40°C, exacerbated by local emissions trapping moisture under inversion layers. Such pollution-driven fogs often form over valleys due to temperature inversions that confine cold air and pollutants near the surface, leading to denser crystal formations compared to rural areas. As of the 2020s, long-term trends show a 60-70% decrease in ice fog days in Fairbanks compared to the mid-20th century, with recent winters (e.g., 2023-2024) featuring fewer than 10 days annually due to rising minimum temperatures from climate warming.^[20]^[24]^[8]^[6] Affected cities like Fairbanks and Yellowknife typically see 10-30 ice fog days per winter, with events ranging from hours to several days in duration, tied closely to inversion strength and emission sources. This contrasts with polar occurrences, where natural moisture drives longer-lasting episodes; continental urban ice fog tends to be more episodic but features elevated ice crystal concentrations from pollution, reaching up to 10,000 crystals per liter in severe cases. Historical observations from the 1940s and 1950s at Alaskan military bases, including Ladd Field near Fairbanks, highlighted increased incidence near airfields, where aircraft exhaust and heating plumes provided abundant nuclei, contributing to persistent fog layers that impaired operations.^[25]^[22]^[8]^[2]

Environmental and Societal Impacts

Visibility and Transportation Effects

Ice fog severely reduces visibility through the scattering of light by its tiny ice crystals, often limiting horizontal visibility to less than 50 meters in extreme cold conditions below -40°C, as observed in Fairbanks, Alaska.^[1] This attenuation primarily results from forward scattering of light within the dense suspension of submicron-sized crystals, which is more pronounced than in water-based fog due to the refractive properties of ice. At night, the reflective nature of ice crystals exacerbates the issue by creating misleading glints and halos around light sources, further disorienting observers and complicating navigation.^[5] In aviation, ice fog poses significant hazards in Arctic regions, frequently grounding flights at remote outposts where visibilities drop below operational thresholds, leading to delays and diversions.^[5] Unlike standard freezing fog, ice fog demands specialized de-icing procedures, as its dry ice crystals adhere more persistently to wings and sensors, potentially altering aerodynamics without liquid runoff.^[26] On roads and rails, ice fog triggers frequent highway closures in areas like Fairbanks, where zero-visibility conditions halt traffic and result in economic losses from emergency responses and lost productivity.^[27] Vehicle surfaces often develop hoar frost through direct deposition of ice crystals from the fog, forming a brittle, opaque layer that impairs windshields and mirrors, increasing accident risks on icy pavements.^[5] Maritime navigation faces rare but acute challenges from ice fog over frozen rivers, where the phenomenon obscures ice edges and currents, complicating icebreaker maneuvers and raising collision hazards with floes.^[28] In such environments, reduced visibility forces slower speeds and reliance on radar, straining operations in narrow channels prone to ice jams.^[29] Mitigation strategies include infrared sensors for early detection of crystal buildup on runways and aircraft, enabling timely interventions, while heated runways maintain clear surfaces by melting deposited ice above freezing thresholds.^[30] During the Cold War era, experimental systems were tested at northern bases to disperse ice fog layers using mechanical methods like helicopter downwash and dry ice seeding, though limitations such as infrequent suitable conditions restricted adoption.^[31] Recent studies indicate that ice fog events in regions like Fairbanks have decreased by 60-70% since the mid-20th century, potentially lessening some transportation disruptions.^[6]

Health and Ecological Consequences

Ice fog poses significant health risks primarily through its role in trapping fine particulate matter (PM2.5) and other pollutants under temperature inversions, leading to elevated concentrations that irritate the respiratory tract. The tiny ice crystals in ice fog can penetrate deep into the lungs, exacerbating conditions such as asthma and chronic obstructive pulmonary disease, particularly in urban settings like Fairbanks, Alaska, where combustion sources contribute to pollution. A study of hospital data from the region found that PM2.5 levels during winter inversion events associated with ice fog were linked to a 6% increased risk of emergency department visits for respiratory issues.^[32]^[33] Long-term exposure to pollutants in ice fog contributes to broader air quality challenges in cold climates, where PM2.5 concentrations often exceed U.S. Environmental Protection Agency standards, raising cardiovascular risks including heart attacks and strokes. The World Health Organization identifies fine particulate pollution as a major factor in global cardiovascular morbidity, with Arctic regions like Fairbanks experiencing wintertime averages that impair public health. Indigenous communities in the Arctic bear a disproportionate burden, with higher baseline rates of respiratory and cardiovascular diseases compounded by limited access to healthcare during prolonged events.^[33]^[34] Ecologically, ice fog reduces sunlight penetration, potentially limiting photosynthesis in tundra plants by diminishing photosynthetically active radiation during critical winter periods. This light blockage can stress vegetation adapted to low-light conditions, indirectly affecting primary productivity in Arctic ecosystems. Furthermore, ice fog modifies snow surface albedo by depositing ice crystals, which lowers reflectivity and enhances absorption of solar radiation, potentially accelerating seasonal snow melt and altering local hydrological cycles.^[2]^[33]

Observation and Research

Detection Techniques

Ice fog detection has evolved significantly since the mid-20th century, transitioning from manual visual observations to advanced remote and in-situ instrumentation. In the 1950s and 1960s, researchers in Alaska relied on visual logs and basic meteorological records to document ice fog occurrences in Fairbanks, noting its association with temperatures below -30°C and low wind speeds.^[13] These early methods, such as those employed by Robinson and Bell in 1956, provided qualitative assessments of visibility reduction but lacked quantitative microphysical details. By the late 20th century, automated weather stations began integrating sensors in Arctic observatories like those at Barrow (now Utqiaġvik), Alaska, enabling continuous monitoring of temperature, humidity, and visibility parameters. Modern systems, such as those in the FRAM-Ice Fog project (2010), combine these with specialized tools for real-time data collection in polar environments.^[5] Remote sensing techniques, particularly LIDAR (light detection and ranging), offer effective profiling of ice fog crystals by measuring backscatter and depolarization ratios. Depolarization ratios greater than 10-20% indicate ice particles, distinguishing ice fog from liquid water fog, as ice crystals depolarize the laser light more strongly due to their non-spherical shapes.^[35] Doppler LIDAR systems, deployed in campaigns like the Ice Fog Field Experiment at Oliktok Point (IFFEXO, 2020), capture radial velocities and particle fall speeds, revealing small ice crystals (<20 μm) typical of ice fog layers near the surface.^[36] These ground-based or airborne LIDARs provide vertical profiles up to several hundred meters, aiding in real-time identification over Arctic sites. In-situ instruments enable direct sampling of ice fog microphysics, focusing on particle size distributions and concentrations. Forward scatter meters, such as the Forward Scattering Spectrometer Probe (FSSP), measure particles in the 2-50 μm range by detecting light scattered at small angles, calibrated for the low refractive index of ice crystals to avoid overestimation in dense fog.^[37] Ice crystal replicators using Formvar film, a technique refined since the 1960s, capture airborne crystals on coated slides for microscopic analysis, revealing habits like droxtals and plates in urban ice fog events.^[12] These balloon-borne or aircraft-mounted devices, as used in early Alaskan studies, quantify concentrations often exceeding 1000 L⁻¹ in persistent ice fog. Satellite-based detection leverages thermal infrared imagery to identify ice fog through contrasts between the cold surface and slightly warmer fog layers. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua and Terra satellites, operational since 2000, detects thin ice fog over polar regions by analyzing brightness temperatures in 11-12 μm channels, where ice crystals exhibit subtle emissivity differences from clear sky.^[5] This method is particularly effective in winter Arctic scenes, identifying ice fog patches via optical depth ratios below 0.1, though challenges arise from overlying clouds.^[38] MODIS data from the FRAM-Ice Fog project validated ice phase algorithms against ground observations, enhancing nowcasting over remote areas.^[5] Visibility metrics for ice fog incorporate specialized systems to account for forward scattering by small ice crystals, which reduce contrast more efficiently than liquid droplets. Runway Visual Range (RVR) systems, using transmissometers or forward scatter sensors at airports like Fairbanks International, measure visibility down to 50 m in ice fog, calibrated with ice-specific extinction coefficients (around 100-200 m⁻¹ for 10 μm particles).^[39] These differ from standard ceilometers, which primarily detect cloud bases via lidar-like backscatter and may overestimate fog top heights in ice conditions due to minimal vertical extent.^[40] RVR data, integrated into automated aviation weather reports since the 1970s, provide critical real-time inputs for safe operations in ice-prone regions.^[36]

Climate Change Implications

Climate change is altering the formation and distribution of ice fog in the Arctic, primarily through rising temperatures and changes in sea ice extent. In interior regions like Fairbanks, Alaska, long-term observations indicate a substantial decline in ice fog occurrence, with the median number of ice fog days per winter decreasing from 16.5 in the 1951–1980 period to 6 in the 1991–2020 period, representing a 60–70% reduction overall. This decrease is attributed to warmer winter temperatures that reduce the frequency of conditions below -30°C necessary for ice crystal nucleation. Conversely, in transitional and coastal zones near retreating sea ice edges, increased open water areas have led to higher moisture availability, potentially elevating related low-visibility events, as more evaporation from exposed ocean surfaces supplies water vapor under persistent cold air outbreaks.^[20]^[41]^[2] These shifts contribute to complex feedback loops in the Arctic climate system. Shrinking sea ice exposes more ocean surface, enhancing evaporation and atmospheric moisture content, which can promote ice fog nucleation by increasing relative humidity and providing additional ice nuclei precursors, thereby amplifying local cooling through radiative effects. Ice fog itself acts as a positive feedback by trapping heat via enhanced downward infrared radiation—up to 60 W m⁻²—potentially warming the surface by about 1 K over several days and influencing sea ice growth or snow cover dynamics. Such interactions may cause seasonal shifts in ice fog prevalence, with "ice fog seasons" potentially shortening in core Arctic areas but extending in marginal zones due to altered thermodynamics.^[2] Projections from climate models suggest reduced overall persistence of ice fog in a warming Arctic, though episodes may become more intense in moisture-rich areas, exacerbating impacts on permafrost thaw by modulating surface energy budgets. These changes could indirectly accelerate permafrost degradation through altered heat fluxes.^[2] Significant research gaps persist, including sparse long-term datasets before 2000 that hinder robust trend analysis in remote Arctic regions. There is a critical need for advanced coupled models that integrate aerosol dynamics, ice nucleation processes, and thermodynamic feedbacks to better simulate ice fog under future climates. Current efforts incorporate ice fog projections into broader frameworks like CMIP6 multimodel ensembles, which improve forecasting of related sea ice and visibility changes, though microphysical parameterizations remain inadequate for precise predictions. Recent studies, such as a 2024 analysis of ice nucleating particles during a Fairbanks ice fog event from January–February 2022, have advanced understanding of aerosol sources and their role in particle formation. Additionally, the FATIMA-IF (Fog and Turbulence Interactions in the Marine Atmosphere–Ice Fog) campaign, conducted from November 15 to December 7, 2025, at the U.S. Department of Energy's North Slope of Alaska site, gathered new field data on ice fog microphysics and environmental conditions to address these gaps.^[43]^[2]^[44]^[15]^[45]

Historical Context

Notable Occurrences

One of the earliest and most significant documented ice fog events occurred in Fairbanks, Alaska, during the winter of 1948/49, marking the beginning of systematic meteorological observations at the local airport. This event, lasting around 10 days, was closely linked to heightened military traffic at Ladd Field (now Fort Wainwright), where vehicle and aircraft exhaust provided key nucleation sites for ice crystal formation. Researchers documented the fallout of these crystals, revealing how anthropogenic emissions exacerbated the fog's persistence under temperatures below -30°F (-34°C).^[20]^[46] More recently, a 2022 inversion-driven ice fog event in Fairbanks, Alaska, persisted from January 29 to February 3, trapping pollutants near the surface and elevating PM2.5 concentrations during the Alaskan Layered Pollution and Chemical Analysis (ALPACA) study. Peer-reviewed analyses linked the fog to local emissions interacting with strong temperature inversions, showing a 18%–78% decrease in ice-nucleating particles as they activated into the fog, underscoring ongoing air quality challenges in Arctic urban areas.^[15] A 2023 study analyzing airport observations from 1948 to 2022 found that ice fog occurrences in the Fairbanks region have declined by 60–70% since 1948, with the greatest reductions in the 1970s and 1980s, likely due to warmer temperatures and changing atmospheric conditions.^[6]

Cultural References

In indigenous cultures of the American West, ice fog is known by the Shoshone term "pogonip," derived from the word paγɨnappɨh meaning "cloud" or "thundercloud," and often translated as "white death" due to its association with severe frostbite and hoarfrost accumulation on trees and landscapes during cold spells in mountain valleys.^[47]^[11] Native American communities viewed pogonip as a perilous phenomenon that coated everything in ice crystals, limiting visibility and exacerbating winter hardships in regions like Nevada and Idaho.^[48] News outlets covered ice fog prominently during the 2017 Fairbanks cold snap, when temperatures plummeted to -50°F, triggering air quality alerts for trapped pollutants that posed health risks to residents.^[49]^[33]

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Ice fog affects the aviation flight conditions. · Aviation accidents over the Arctic regions will increase about 25 times. · Ice fog cannot be predicted by ...
[40]
[PDF] Federal Coordinator for Meteorological Services and Supporting ...
"Visual Range in Ice Fog." Journal of Applied Meteorology, Vol. 8, Aug ... to RVR by a runway visual range signal data converter system (7). Principal ...
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[PDF] JO 7900.5E, Surface Weather Observing
Jan 15, 2020 · The Chapter for Runway Visual Range (RVR) reporting has been deleted since RVR reporting is ... also called ice fog. Freezing Precipitation. Any ...
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Adapting to a Foggy Future Along Trans‐Arctic Shipping Routes
Apr 24, 2023 · About 20%–30% of Arctic shipping routes experience frequent sea fog frequency more than 20% · Sea fog increases the shipping time by 23%–27% ...
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https://ascmo.copernicus.org/articles/6/31/2020/
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Possible impacts of climate change on fog in the Arctic and subpolar ...
Apr 30, 2020 · A conventional parameterization of midlatitude warm fog occurrence, based on in situ observations, is employed to estimate marine surface ...
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Optimizing sea ice parameters mitigates the underestimation of ...
Aug 29, 2025 · Introduction. The Arctic is warming at nearly three to four times the global average1,2, resulting in significant reductions in sea ice area ...
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[PDF] UNIVERSITY OF ALASKA ICE FOG: LOW TEMPERATURE AIR ...
an adsorption surface of about 2000 cm per cubic meter of air. As the crystals ... 3 spherical crystals with diameter of 25 P , and concentration 1 crystal per cm ...
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[PDF] Satellite Analyses of Antarctic Katabatic Wind Behavior
Katabatic winds propa- gating horizontally for hundreds of kilometers over the southwestern. Ross Sea do not exhibit the expected influence of the Coriolis.
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POGONIP Definition & Meaning - Merriam-Webster
The meaning of POGONIP is a dense winter fog containing frozen particles that is formed in deep mountain valleys of the western U.S.. Did you know?
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May I have a word about… pogonip and other weather phenomena
Dec 18, 2022 · It comes from the word “payinappih”, used by the Native American Shoshone tribe to describe the frozen fogs of fine ice needles that occur in ...
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To Build a Fire - Short Story by Jack London - American Literature
The man flung a look back along the way he had come. The Yukon lay a mile wide and hidden under three feet of ice. On top of this ice were as many feet of snow.
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The Film - Chasing Ice
Chasing Ice is the story of one man's mission to change the tide of history by gathering undeniable evidence of our changing planet.Missing: modern fog
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The Thing (1982) - IMDb
Rating 8.2/10 (513,435) A research team in Antarctica is hunted by a shape-shifting alien that assumes the appearance of its victims.Full cast & crew · Trivia · The Thing · Parents guide
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It's so cold in Alaska that even Alaskans are complaining - USA Today
Jan 19, 2017 · Fairbanks dropped to 50 below zero for the first time in five years Wednesday, Anchorage climatologist Brian Brettschnider said, triggering spooky ice fog ...
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The Stunning Survival Story of Ernest Shackleton and His ...
Oct 21, 2020 · The men on the British expedition to Antarctica endured entrapment, hunger, frigid weather, angry seas—and near madness.Missing: fog | Show results with:fog