scholarly journals Secondary ice production during the break-up of freezing water drops on impact with ice particles

2021 ◽  
Vol 21 (24) ◽  
pp. 18519-18530
Author(s):  
Rachel L. James ◽  
Vaughan T. J. Phillips ◽  
Paul J. Connolly
Keyword(s):  
Laboratory Study ◽  
Water Drop ◽  
Supercooled Water ◽  
Glass Slide ◽  
Ice Formation ◽  
Production Mechanism ◽  
Temperature Range ◽  
Ice Particles ◽  
Water Drops ◽  
Ice Production

Abstract. We provide the first dedicated laboratory study of collisions of supercooled water drops with ice particles as a secondary ice production mechanism. We experimentally investigated collisions of supercooled water drops (∼ 5 mm in diameter) with ice particles of a similar size (∼ 6 mm in diameter) placed on a glass slide at temperatures >-12 ∘C. Our results showed that secondary drops were generated during both the spreading and retraction phase of the supercooled water drop impact. The secondary drops generated during the spreading phase were emitted too fast to quantify. However, quantification of the secondary drops generated during the retraction phase with diameters >0.1 mm showed that 5–10 secondary drops formed per collision, with approximately 30 % of the secondary drops freezing over a temperature range between −4 and −12 ∘C. Our results suggest that this secondary ice production mechanism may be significant for ice formation in atmospheric clouds containing large supercooled drops and ice particles.

scholarly journals Secondary ice production during the break-up of freezing water drops on impact with ice particles

2021 ◽  
Author(s):  
Rachel L. James ◽  
Vaughan T. J. Phillips ◽  
Paul J. Connolly
Keyword(s):  
Laboratory Study ◽  
Water Drop ◽  
Supercooled Water ◽  
Glass Slide ◽  
Ice Formation ◽  
Production Mechanism ◽  
Temperature Range ◽  
Ice Particles ◽  
Water Drops ◽  
Ice Production

Abstract. We experimentally investigated collisions of supercooled water drops (∼ 5 mm in diameter) with ice particles of a similar size placed on a glass slide at temperatures T ≥ −12 °C. Our results showed that secondary drops were generated during both the spreading and retraction phase of the supercooled water drop impact. The secondary drops generated during the spreading phase were emitted too fast to quantify. However, quantification of the secondary drops generated during the retraction phase with diameters > 0.1 mm showed that 5–10 secondary drops formed per collision, with approximately 30 % of the secondary drops freezing over a temperature range of −4 °C ≤ T ≤ −12 °C. Our investigation provides the first dedicated laboratory study of collisions of supercooled water drops with ice particles as a secondary ice production mechanism. Our results suggest that this secondary ice production mechanism may be significant for ice formation in atmospheric clouds containing large supercooled drops and ice particles.

A laboratory and model investigation of secondary ice production during to supercooled drop collisions with ice surfaces 

2021 ◽  
Author(s):  
Paul Connolly ◽  
Rachel James ◽  
Vaughan Phillips
Keyword(s):  
Laboratory Data ◽  
Ice Formation ◽  
Atmospheric Sciences ◽  
Ice Particles ◽  
Cold Room ◽  
Mode 2 ◽  
Rain Drops ◽  
Break Up ◽  
Ice Surfaces ◽  
Ice Production

<p>This work presents new laboratory data investigating collisions between supercooled drops and ice particles as a source of secondary ice particles in natural clouds. Furthermore we present numerical model simulations to put the laboratory measurements into context.</p><p>Secondary ice particles form during the breakup of freezing drops due to so-called “spherical freezing” (or Mode 1), where an ice shell forms around the freezing drop. This process has been studied and observed for drops in free-fall in laboratory experiments since the 1960s, and also more recently by Lauber et al. (2018) with a high-speed camera. Aircraft field measurements (Lawson et al. 2015) and lab data (Kolomeychuk et al. 1975) suggest that such a process is dependent on the size of drops, with larger drops being more effective at producing secondary ice.  Collision induced break-up of rain drops has been well studied with pioneering investigations in the mid-1980s, and numerous modelling studies showing that it is responsible for observed trimodal rain drop size distributions in the atmosphere, which can be well approximated by an exponential distribution.</p><p> </p><p>In mixed-phase clouds we know that rain-drops can collide with more massive ice particles. This, depending on the type of collision, may lead to the break-up of the supercooled drop (e.g. as hinted by Latham and Warwicker, 1980), potentially stimulating secondary ice formation (Phillips et al. 2018 - non-spherical, Mode 2).  There is a dearth of laboratory data investigating this mechanism.  This mechanism is the focus of the presentation.</p><p>Here we present the results of recent experiments where we make use of the University of Manchester (UoM) cold room facility. The UoM cold room facility consists of 3 stacked cold rooms that can be cooled to temperatures below -55 degC. A new facility has been built to study secondary ice production via Mode 2 fragmentation. We generate supercooled drops at the top of the cold rooms and allow them to interact with different ice surfaces near the bottom. This interaction is filmed with a new camera setup.</p><p>Our latest results will be presented at the conference.</p><p>References</p><p>Kolomeychuk, R. J., D. C. McKay, and J. V. Iribarne. 1975. “The Fragmentation and Electrification of Freezing Drops.” <em>Journal of the Atmospheric Sciences</em> 32 (5): 974–79. https://doi.org/10.1175/1520-0469(1975)032<0974>2.0.CO;2.</p><p>Latham, J., and R. Warwicker. 1980. “Charge Transfer Accompanying the Splashing of Supercooled Raindrops on Hailstones.” Quarterly Journal of the Royal Meteorological Society 106 (449): 559–68. https://doi.org/10.1002/qj.49710644912.</p><p>Lauber, Annika, Alexei Kiselev, Thomas Pander, Patricia Handmann, and Thomas Leisner. 2018. “Secondary Ice Formation during Freezing of Levitated Droplets.” Journal of the Atmospheric Sciences 75 (8): 2815–26. https://doi.org/10.1175/JAS-D-18-0052.1.</p><p>Lawson, R. Paul, Sarah Woods, and Hugh Morrison. 2015. “The Microphysics of Ice and Precipitation Development in Tropical Cumulus Clouds.” Journal of the Atmospheric Sciences 72 (6): 2429–45. https://doi.org/10.1175/JAS-D-14-0274.1.</p><p> </p><p> </p>

Anchor ice in polar oceans

2013 ◽  
Vol 37 (4) ◽  
pp. 468-483 ◽  
Author(s):  
Sarah M. Mager ◽  
Inga J. Smith ◽  
Edward W. Kempema ◽  
Benjamin J. Thomson ◽  
Gregory H. Leonard
Keyword(s):  
Supercooled Water ◽  
Ice Formation ◽  
Common Mechanism ◽  
Marine Environments ◽  
Ice Shelves ◽  
Antarctic Expedition ◽  
Anchor Ice ◽  
Ice Production ◽  
Physical Reasons ◽  
Future Work

One feature of high-latitude areas is the formation of ice clusters attached to the beds of rivers, lakes and the sea. This anchor ice, as it is widely known, plays an important role in mobilizing bed sediments, as well as ecological roles as a food source, habitat and potentially fatal environment. Much work has been devoted to fluvial anchor ice in the Northern Hemisphere, yet comparatively little work has described anchor ice in polar marine environments, despite its description by Antarctic expedition scientists over a century ago. In this paper, we review the current understanding of anchor ice formation in polar marine environments. Supercooled water is a necessity for anchor ice to form and frazil adhesion is the most likely common mechanism for initial anchor ice growth. Strong biological zonation has led some authors to suggest that anchor ice does not form to depths of greater than 33 m, yet in Antarctica there appear to be no physical reasons for such a limit given the production of supercooled water to substantial depths associated with ice shelves. Future work should focus on the potential extent of anchor ice production and identify the key oceanographic, glaciological and meteorological conditions conducive to its formation.

scholarly journals The freeezing behaviour of supercooled water drops

1976 ◽  
Vol 17 (75) ◽  
pp. 99-109 ◽  
Author(s):  
M. J. Gay ◽  
J. Latham
Keyword(s):  
Relative Humidity ◽  
Mass Loss ◽  
Supercooled Water ◽  
Additional Mechanism ◽  
Ice Particles ◽  
Containment System ◽  
Water Drops ◽  
Almost All ◽  
Visual Observations

Abstract An electrodynamic containment system has been used to study the freeezing behaviour of supercooled water drops, of radius range 25 to 90 μm. The drops were freozen at temperatures between 0 and — 29°C in an environment whose relative humidity was approximately 90% with respect to ice. Freezing events were observed visually and photographically, and measurements were mager of the accompanying freactional mass loss Δm/m. The most common moger of freeezing (70% of the drops studied) resulted in an apparently spherical ice particle. However, 18% exhibited spikes or other protuberances and the freeezing of 3% was accompanied by the ejection of numerous ice particles. In each of these situations values of Δm/m ranged freom about 5 to 15%. A further 9% of the drops exhibited one or more secondary mass-loss events, occurring several seconds after the freeezing process was complete; these were thus indicative of the ejection of ice particles. Almost all of the values of Δm/m were significantly in excess of those predicted on the basis of evaporation during freeezing, suggesting that an additional mechanism of mass loss was also present. The measured freeezing times were consigerrably shorter than the classical values—at least, for the larger drops freeezing at warmer temperatures. Some visual observations were consistent with the “supersaturation wave” around a freeezing drop, which has been predicted by Nix and Fukuta (1974).

scholarly journals The Freeezing behaviour of Supercooled Water Drops

1976 ◽  
Vol 17 (75) ◽  
pp. 99-109 ◽  
Author(s):  
M. J. Gay ◽  
J. Latham
Keyword(s):  
Relative Humidity ◽  
Mass Loss ◽  
Supercooled Water ◽  
Additional Mechanism ◽  
Ice Particles ◽  
Containment System ◽  
Water Drops ◽  
Almost All ◽  
Visual Observations

AbstractAn electrodynamic containment system has been used to study the freeezing behaviour of supercooled water drops, of radius range 25 to 90 μm. The drops were freozen at temperatures between 0 and — 29°C in an environment whose relative humidity was approximately 90% with respect to ice. Freezing events were observed visually and photographically, and measurements were mager of the accompanying freactional mass loss Δm/m.The most common moger of freeezing (70% of the drops studied) resulted in an apparently spherical ice particle. However, 18% exhibited spikes or other protuberances and the freeezing of 3% was accompanied by the ejection of numerous ice particles. In each of these situations values of Δm/m ranged freom about 5 to 15%. A further 9% of the drops exhibited one or more secondary mass-loss events, occurring several seconds after the freeezing process was complete; these were thus indicative of the ejection of ice particles.Almost all of the values of Δm/m were significantly in excess of those predicted on the basis of evaporation during freeezing, suggesting that an additional mechanism of mass loss was also present. The measured freeezing times were consigerrably shorter than the classical values—at least, for the larger drops freeezing at warmer temperatures. Some visual observations were consistent with the “supersaturation wave” around a freeezing drop, which has been predicted by Nix and Fukuta (1974).

scholarly journals Ice formation and development in aged, wintertime cumulus over the UK : observations and modelling

2011 ◽  
Vol 11 (11) ◽  
pp. 30797-30851 ◽  
Author(s):  
I. Crawford ◽  
K. N. Bower ◽  
T. W. Choularton ◽  
C. Dearden ◽  
J. Crosier ◽  
...  
Keyword(s):  
Particle Production ◽  
Number Concentration ◽  
Basic Knowledge ◽  
Ice Formation ◽  
Ice Crystal ◽  
Model Simulations ◽  
Ice Nuclei ◽  
Ice Particles ◽  
Ice Production

Abstract. In-situ high resolution aircraft measurements of cloud microphysical properties were made in coordination with ground based remote sensing observations of Radar and Lidar as part of the Aerosol Properties, PRocesses And InfluenceS on the Earth's climate (APPRAISE) project. A narrow but extensive line (~100 km long) of shallow convective clouds over the southern UK was studied. Cloud top temperatures were observed to be higher than ~−8 °C, but the clouds were seen to consist of supercooled droplets and varying concentrations of ice particles. No ice particles were observed to be falling into the cloud tops from above. Current parameterisations of ice nuclei (IN) numbers predict too few particles will be active as ice nuclei to account for ice particle concentrations at the observed near cloud top temperatures (~−7 °C). The role of biological particles, consistent with concentrations observed near the surface, acting as potential efficient high temperature IN is considered important in this case. It was found that very high concentrations of ice particles (up to 100 L−1) could be produced by powerful secondary ice particle production emphasising the importance of understanding primary ice formation in slightly supercooled clouds. Aircraft penetrations at −3.5 °C, showed peak ice crystal concentrations of up to 100 L−1 which together with the characteristic ice crystal habits observed (generally rimed ice particles and columns) suggested secondary ice production had occurred. To investigate whether the Hallett-Mossop (HM) secondary ice production process could account for these observations, ice splinter production rates were calculated. These calculated rates and observations could only be reconciled provided the constraint that only droplets >24 μm in diameter could lead to splinter production, was relaxed slightly by 2 μm. Model simulations of the case study were also performed with the WRF (Weather, Research and Forecasting) model and ACPIM (Aerosol Cloud and Precipitation Interactions Model) to investigate the likely origins of the ice phase in these slightly supercooled clouds and to assess the role played by the HM process in this and in controlling precipitation formation under these conditions. WRF results showed that while HM does act to increase the mass and number concentration of ice particles produced in the model simulations, in the absence of HM, the ice number concentration arising from primary ice nucleation alone (several L−1) was apparently sufficient to sustain precipitation although the distribution of the precipitation was changed. Thus in the WRF model the HM process was shown to be non-critical for the formation of precipitation in this particular case. However, this result is seen to be subject to an important caveat concerning the simulation of the cloud macrostructure. The model was unable to capture a sharp temperature inversion seen in the radiosonde profiles at 2 km, and consequently the cloud top temperature in the model was able to reach lower values than observed in-situ or obtained from satellite data. ACPIM simulations confirmed the HM process to be a very powerful mechanism for producing the observed high ice concentrations, provided that primary nucleation occured to initiate the ice formation, and large droplets were present which then fell collecting the primary ice particles to form instant rimer particles. However, the time to generate the observed peak ice concentrations was found to be dependant on the number of primary IN present (decreasing with increasing IN number). This became realistic (around 20 min) only when the temperature input to the existing IN parameterisation was 6 °C lower than observed at cloud top, highlighting the requirement to improve basic knowledge of the number and type of IN active at these high temperatures. In simulations where cloud droplet numbers were realistic the precipitation rate was found to be unaffected by HM, with warm rain processes dominating precipitation development in this instance.

Supercooled Water Drops Do Not Freeze During Impact on Hybrid Janus Particle-Based Surfaces

2018 ◽  
Vol 31 (1) ◽  
pp. 112-123 ◽  
Author(s):  
Madeleine Schwarzer ◽  
Thomas Otto ◽  
Markus Schremb ◽  
Claudia Marschelke ◽  
Hisaschi T. Tee ◽  
...  
Keyword(s):  
Supercooled Water ◽  
Janus Particle ◽  
Water Drops

scholarly journals A comparison between polynya area and associated ice production with mooring-based measurements of temperature, salinity and currents in the southwestern Ross Sea, Antarctica

2011 ◽  
Vol 52 (57) ◽  
pp. 291-300 ◽  
Author(s):  
Stefan Kern ◽  
Stefano Aliani
Keyword(s):  
Ross Sea ◽  
Time Lag ◽  
Ice Formation ◽  
Terra Nova Bay ◽  
In Situ Observations ◽  
Satellite Microwave ◽  
Terra Nova ◽  
Ice Production ◽  
The Impact

AbstractWintertime (April–September) area estimates of the Terra Nova Bay polynya (TNBP), Antarctica, based on satellite microwave radiometry are compared with in situ observations of water salinity, temperature and currents at a mooring in Terra Nova Bay in 1996 and 1997. In 1996, polynya area anomalies and associated anomalies in polynya ice production are significantly correlated with salinity anomalies at the mooring. Salinity anomalies lag area and/or ice production anomalies by about 3 days. Up to 50% of the variability in the salinity at the mooring position can be explained by area and/or ice production anomalies in the TNBP for April–September 1996. This value increases to about 70% when considering shorter periods like April–June or May–July, but reduces to 30% later, for example July–September, together with a slight increase in time lag. In 1997, correlations are smaller, less significant and occur at a different time lag. Analysis of ocean currents at the mooring suggests that in 1996 conditions were more favourable than in 1997 for observing the impact of descending plumes of salt-enriched water formed in the polynya during ice formation on the water masses at the mooring depth.

New Empirical Formulation for the Sublimational Breakup of Graupel and Dendritic Snow

2021 ◽  
Author(s):  
Akash Deshmukh ◽  
Vaughan T. J. Phillips ◽  
Aaron Bansemer ◽  
Sachin Patade ◽  
Deepak Waman
Keyword(s):  
Dynamic Equilibrium ◽  
Thought Experiment ◽  
Atmospheric Model ◽  
Scaling Analysis ◽  
Quasi Equilibrium ◽  
Ice Particles ◽  
Ice Multiplication ◽  
Bin Microphysics ◽  
Ice Production ◽  
New Formulation

AbstractIce fragments are generated by sublimation of ice particles in subsaturated conditions in natural clouds. Conceivably, such sublimational breakup would be expected to cause ice multiplication in natural clouds. Any fragment that survives will grow to become ice precipitation that may sublimate and fragment further.As a first step towards assessing this overlooked process, a formulation is proposed for the number of ice fragments from sublimation of ice particles for an atmospheric model. This is done by amalgamating laboratory observations from previously published studies. The concept of a ‘sublimated mass activity spectrum’ for the breakup is applied to the dataset. The number of ice fragments is determined by the relative humidity over ice and the initial size of the parent ice particles. The new formulation applies to dendritic crystals and heavily rimed particles only.Finally, a thought experiment is performed for an idealized scenario of subsaturation with in-cloud descent. Scaling analysis yields an estimate of an ice enhancement ratio of about 5 (50) within a weak deep convective downdraft of about 2 m s-1, for an initial monodisperse population of dendritic snow (graupel) particles of 3 L-1 and 2 mm . During descent, there is a dynamic equilibrium between continual emission of fragments and their depletion by sublimation. A simplified bin microphysics parcel model exhibits this dynamical quasi-equilibrium, consistent with the thought experiment. The fragments have average lifetimes of around 90 and 240 seconds for dendrites and graupel respectively. Sublimational breakup is predicted to cause significant secondary ice production.

scholarly journals Preliminary results of tritium analyses in basal ice, Matanuska Glacier, Alaska, U.S.A.: evidence for subglacial ice accretion

1996 ◽  
Vol 22 ◽  
pp. 126-133 ◽  
Author(s):  
Jeffrey C. Strasser ◽  
Daniel E. Lawson ◽  
Grahame J. Larson ◽  
Edward B. Evenson ◽  
Richard B. Alley
Keyword(s):  
Drainage System ◽  
Supercooled Water ◽  
Ice Formation ◽  
Flowing Water ◽  
Ice Accretion ◽  
Preliminary Results ◽  
Basal Ice ◽  
Basal Zone ◽  
Matanuska Glacier ◽  
Initial Results

The stratified-facies ice of the basal zone of Matanuska Glacier, Alaska. U.S.A., contains significant concentrations of anthropogenic tritium, whereas unaltered englacial-zone ice is devoid of tritium. Supercooled water flowing through subglacial conduits during the melt season likewise contains tritium, as does frazil and other platy ice that nucleates and grows within this subglacially flowing water. These initial results demonstrate net accretion of more than 1.4 m of stratified basal-zone ice since initiation of above-ground, thermonuclear bomb testing in 1952. Furthermore, these results support a theory of basal ice formation by ice accretion and debris entrainment from supercooled water within a distributed subglacial drainage system.

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