Sentences with phrase «of ice nuclei»

These studies concern the formation of ice nuclei in supercooled vapours at low temperatures.

However, past studies of such Arctic mixed - phase clouds have been unable to explain the measured abundance of ice crystals larger than 100 micrometers in maximum dimension (the size range where measurements are available), given observed environmental conditions and the measured concentrations of ice nuclei that could be entrained into the observed shallow cloud layers from aloft.

We found that without crystal aggregation, our simulations using low - density dendrites were able to predominantly match the in situ measurements, but this rough match required either increasing the overlying ice nucleus concentration fourfold or assuming a reservoir of ice nuclei from the surface layer to be entrained from the underlying, decoupled surface layer (both conceivable; see paper for details).

Thus, the entrainment source of ice nuclei was relatively large (compared to previous case studies) and the sedimentation sink of ice crystals was small.

In the absence of any ice nuclei, the freezing of supercooled water droplets of a few micrometres in radius, in a process called homogeneous ice nucleation, requires temperatures at or lower than − 39 °C (− 38 °F).

The paper, Clarifying the Dominant Sources and Mechanisms of Cirrus Cloud Formation, D, J. Cziczo, et al. find that most of the ice nuclei form around mineral dust.

The current research project sought to determine how lead from daily human activities affects formation of ice nuclei.

These studies concern the formation of ice nuclei in supercooled vapours at low temperatures.

The team found there were much fewer of these ice nuclei than there were actual ice crystals in the clouds.

Over a third of the ice nuclei generated contained lead, suggesting it is a highly - efficient nucleator.

It has empirically derived dependencies on the chemistry and surface area of multiple species of ice nucleus (IN) aerosols.

However, we caution that these results do not imply that the ice formation problem is solved because several unique conditions favored agreement between simulated and observed ice crystal number concentrations in this case: overlying ice nucleus concentrations much greater than in - cloud ice crystal concentrations, very slow - falling ice crystals, and the possible presence of an ice nucleus reservoir below a decoupled surface layer.

Not exact matches

«The icy small bodies warm up as they approach the Sun, and the ice sublimes to form a coma [a dense cloud of gas and dust particles around a nucleus] and often a tail, making the comets observable,» she explained.

There, they calculated the so - called free energy cost for the formation of small ice crystal nuclei.

In the cool upper atmosphere, ice crystals would have formed around tiny nuclei of volcanic dust, before falling back to Earth.

Comet Siding Spring's nucleus — a nugget of ice and rock measuring no more than half a kilometer (about 1/3 mile)-- is small, but the coma is expansive, stretching out a million kilometers (more than 600,000 miles) in every direction.

Either the nucleus now resembles a baked Alaska — a burnt crust insulating a core of ice and preventing it from releasing gas that would glow — or, more likely, it has broken up and we are just seeing a fragment.

Circling the South Pole, ANITA's antennas will scan a million cubic kilometers of ice at a time, looking for the telltale radio waves emitted when an ultrahigh - energy neutrino hits a nucleus in ice.

Researchers from the IceCube project will place a string of Digital Optical Modules into this hole, which can detect the faint signal produced on the rare occasion when a neutrino collides directly with the nucleus of an atom in a molecule of ice.

ANITA will exploit a phenomenon known as the Askaryan effect, whereby high - energy neutrinos streaming through ice, salt or sand produce a cone of radio waves when they collide with a nucleus in the material.

The gases all originate from the hodgepodge of ices, rock and dust that make up the nucleus.

This had the effect of pouring a bucket of ice water on sleepy viruses to keep them awake once they reach the nucleus.

The authors suggest that the cyclic sublimationcondensation of ice triggered by varying illumination conditions may be a general process acting on cometary nuclei.

Ice nuclei, a type of aerosol particle in the atmosphere, form the ice crystals in mixed - phase clouIce nuclei, a type of aerosol particle in the atmosphere, form the ice crystals in mixed - phase clouice crystals in mixed - phase clouds.

nucleus (in astronomy) The rocky body of a comet, sometimes carrying a jacket of ice or frozen gases.

When comets venture into the more intense sunlight of the inner solar system, the ices on the comet nucleus begin to melt and fall away.

Airborne particles in the form of naturally occurring dusts and human - produced aerosols can serve as ice nuclei, sites around which water vapor condenses into clouds.

comet A celestial object consisting of a nucleus of ice and dust.

Aerosols that are effective for the conversion of water vapour to ice crystals are referred to as ice nuclei.

The presence of cloud condensation and ice nuclei in air parcels is tested by using cloud chambers in which controlled temperatures and relative humidities are specified.

In contrast to cloud condensation nuclei, the most effective ice nuclei are hydrophobic (having a low affinity for water) with molecular spacings and a crystallographic structure close to that of ice.

The third regional modeling submission, Barthélemy et al., uses the ice - ocean Nucleus for European Modeling of the Ocean Louvain - la - Neuve Sea Ice Model (NEMO - LIM3) model and is initialized on 1 August 20ice - ocean Nucleus for European Modeling of the Ocean Louvain - la - Neuve Sea Ice Model (NEMO - LIM3) model and is initialized on 1 August 20Ice Model (NEMO - LIM3) model and is initialized on 1 August 2014.

Ice nuclei are of three types: deposition nuclei, contact nuclei, and freezing nuclei.

Barthélemy et al, 5.1 (4.5 - 5.6), Modeling Our estimate is based on results from ensemble runs with the global ocean - sea ice coupled model Nucleus for European Modeling of the Ocean Louvain - la - Neuve Sea Ice Model (NEMO - LIMice coupled model Nucleus for European Modeling of the Ocean Louvain - la - Neuve Sea Ice Model (NEMO - LIMIce Model (NEMO - LIM3).

In addition, naturally occurring bacteria found in decayed leaf litter can serve as ice nuclei at temperatures of less than about − 4 °C (24.8 °F).

In a process called cloud seeding, silver iodide, with effective ice - nucleating temperatures of less than − 4 °C, has been used for years in attempts to convert supercooled water to ice crystals in regions with a scarcity of natural ice nuclei.

Contact and freezing nuclei, in contrast, are associated with the conversion of supercooled water to ice.

Including aggregation, in addition to quadrupled ice nucleus concentrations aloft or an ice nucleus reservoir below, allowed the simulations to roughly match the in situ properties when assuming the presence of low - density dendrites and their aggregates (Fig. 2).

We also note that agreement between observed and simulated ice crystal number concentrations in our study required the concentration of entrained ice nuclei to be much greater than the number concentration of ice crystals, which conflicts with studies that indicate that entrained ice nucleus concentrations are equal to in - cloud ice crystal concentrations.

The aircraft also made in situ measurements of cloud microphysics and ice nuclei, as well as meteorological state parameters and radiative fluxes, which were important study inputs.

The underlying mechanism is that charged aerosols are more effective than neutral aerosols as ice nuclei (i.e., electrofreezing) and that the enhanced collections of charged evaporation nuclei by supercooled droplets enhance the production of ice by contact ice nucleation (i.e., electroscavenging).

On the other hand, if some of the anthropogenic aerosols act as ice nuclei, supercooled clouds could be converted into ice clouds by the glaciation indirect effect (Lohmann, 2002), resulting in more efficient precipitation formation.

Aerosols may influence climate in several ways: directly through scattering and absorbing radiation (see Aerosol — radiation interaction) and indirectly by acting as cloud condensation nuclei or ice nuclei, modifying the optical properties and lifetime of clouds (see Aerosol — cloud interaction).

Their freezing can either be triggered by aerosol particles acting as a so - called ice nuclei (IN), or occur homogeneously (without IN) at about − 38 ◦ C The goal of many laboratory studies was and is to assess the ice nucleation ability of selected aerosol particles of a... http://search.proquest.com/openview/421dd0783b387a8e030902328dcc6f23/1.pdf?pq-origsite=gscholar&cbl=105744

Interactions with the hydrological cycle, and additional impacts on the radiation budget, occur through the role of aerosols in cloud microphysical processes, as aerosol particles act as cloud condensation nuclei (CCN) and ice nuclei (IN).

When endothermic reacting (toxic) ice nucleating materials are utilized on a massive scale for climate intervention / modification programs, convection is greatly impacted, too many condensation nuclei are present, and precipitation is generally greatly reduced (from what it would have otherwise been) in the core of the engineered chemical cool - down zones.