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- Author or Editor: J. Rosinski x
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Abstract
Abstract
Abstract
By melting concentric layers of ice, the size distribution and concentration of solid water-insoluble particles accumulated in hailstones were determined for three hailstorms in Colorado. It was found that in approximately 50 per cent of the hailstones analyzed, particle concentration in ice increased with radial distance. Following an equation derived for this category of hailstones, a relationship is shown among liquid water content of a cloud, concentration of solid particles in cloud droplets, speed of the hailstone, and its residence time in the atmosphere. Spatial distribution of solid particles in hailstones was also determined by slicing hailstones and subsequently separating particles from the ice by sublimation under low pressure. It was found that some of the hailstones analyzed were oriented during their growth.
Abstract
By melting concentric layers of ice, the size distribution and concentration of solid water-insoluble particles accumulated in hailstones were determined for three hailstorms in Colorado. It was found that in approximately 50 per cent of the hailstones analyzed, particle concentration in ice increased with radial distance. Following an equation derived for this category of hailstones, a relationship is shown among liquid water content of a cloud, concentration of solid particles in cloud droplets, speed of the hailstone, and its residence time in the atmosphere. Spatial distribution of solid particles in hailstones was also determined by slicing hailstones and subsequently separating particles from the ice by sublimation under low pressure. It was found that some of the hailstones analyzed were oriented during their growth.
Abstract
Population of cloud droplets in a cloud may be decreased under some circumstances by their removal (along with other particles) by an ice crystal growing on an ice-forming nucleus. Further condensation of water vapor should take place on remaining cloud droplets, which should consequently grow to larger sizes.
Abstract
Population of cloud droplets in a cloud may be decreased under some circumstances by their removal (along with other particles) by an ice crystal growing on an ice-forming nucleus. Further condensation of water vapor should take place on remaining cloud droplets, which should consequently grow to larger sizes.
Abstract
Varying concentrations of different sized, solid, water-insoluble particles in rainwater and hailstones collected during thunderstorms indicate the existence of several scavenging mechanisms of micron-size particles. It is shown that Stefan flow is probably the predominant mechanism of in-cloud scavenging of particles 1.5–5 μ in diameter when solid (ice crystal) and liquid (supercooled cloud droplet) phases are present simultaneously. Particles larger than 5 μ in diameter were scavenged primarily by impaction. On many occasions, concentration of particles larger than 100 μ diameter in rainwater was found to be inversely proportional to rainfall intensity. Studies of spatial distribution of solid particles in hailstones should be supplemented by isotopic analysis.
Abstract
Varying concentrations of different sized, solid, water-insoluble particles in rainwater and hailstones collected during thunderstorms indicate the existence of several scavenging mechanisms of micron-size particles. It is shown that Stefan flow is probably the predominant mechanism of in-cloud scavenging of particles 1.5–5 μ in diameter when solid (ice crystal) and liquid (supercooled cloud droplet) phases are present simultaneously. Particles larger than 5 μ in diameter were scavenged primarily by impaction. On many occasions, concentration of particles larger than 100 μ diameter in rainwater was found to be inversely proportional to rainfall intensity. Studies of spatial distribution of solid particles in hailstones should be supplemented by isotopic analysis.
Abstract
Silver iodide particles deposited on vegetation may photolyse and combine with natural terpenes from tree oils to form compounds which either themselves become aerosols, or become attached to aerosol particles. In either case the new compounds may become active centers acting as freezing nuclei. Silver iodide particles may persist for several months when deposited on coniferous trees, and may release variable doses of such freezing nuclei during that time. Although the concentrations of ice nuclei so produced are probably too small to influence precipitation, they may nevertheless contaminate large areas and thus may be significant for long-range research programs concerned with measuring natural concentrations of freezing nuclei.
Abstract
Silver iodide particles deposited on vegetation may photolyse and combine with natural terpenes from tree oils to form compounds which either themselves become aerosols, or become attached to aerosol particles. In either case the new compounds may become active centers acting as freezing nuclei. Silver iodide particles may persist for several months when deposited on coniferous trees, and may release variable doses of such freezing nuclei during that time. Although the concentrations of ice nuclei so produced are probably too small to influence precipitation, they may nevertheless contaminate large areas and thus may be significant for long-range research programs concerned with measuring natural concentrations of freezing nuclei.
Abstract
Aluminized Mylar bags are used by many researchers to store aerosol samples for later analysis. Our results show that the rate of deposition of unipolar unit-charged aerosols to the walls can be extremely high and is unpredictable for different bags that by inspection appear to be in identical condition. Filling losses and the rate of decay of monodispersed unit-charged aerosols smaller than 0.2 μm in aluminized Mylar bags were shown to be strongly dependent on the electrostatic charges existing on the bags' surfaces despite the aluminum coating; for monodispersed charge-equilibrated aerosols the rate of deposition was much lower. Application of antistatic agents to the bags' interior or exterior surfaces increased the lifetimes of aerosols stored within. But the application of the antistatic agent tested did not completely neutralize the charges residing on the surfaces of the bags. A paper bag with an interior aluminum foil coating was shown to be far superior to the aluminized Mylar bag in handling convenience and for aerosol storage. A method for estimating aerosol deposition rate limits in the absence of electrostatic fields was deduced.
Abstract
Aluminized Mylar bags are used by many researchers to store aerosol samples for later analysis. Our results show that the rate of deposition of unipolar unit-charged aerosols to the walls can be extremely high and is unpredictable for different bags that by inspection appear to be in identical condition. Filling losses and the rate of decay of monodispersed unit-charged aerosols smaller than 0.2 μm in aluminized Mylar bags were shown to be strongly dependent on the electrostatic charges existing on the bags' surfaces despite the aluminum coating; for monodispersed charge-equilibrated aerosols the rate of deposition was much lower. Application of antistatic agents to the bags' interior or exterior surfaces increased the lifetimes of aerosols stored within. But the application of the antistatic agent tested did not completely neutralize the charges residing on the surfaces of the bags. A paper bag with an interior aluminum foil coating was shown to be far superior to the aluminized Mylar bag in handling convenience and for aerosol storage. A method for estimating aerosol deposition rate limits in the absence of electrostatic fields was deduced.
Abstract
Silver chloride, bromide and iodide hydrosol particles were studied as freezing nuclei. Ice nucleation was enhanced through the exchange of iodine ions on the surface of solid silver iodide, using iodine monobromide. Drops containing AgI in concentrations larger than 10−4 gm cm−3 froze between −3 and −3.4C in the presence of iodine monobromide, supplied from the reaction between potassium iodide and N-bromosuccinimide. These results give support to Fukuta-Paik calculations showing that Ag+ sites in AgI are responsible for the enhancement of ice nucleability.
Abstract
Silver chloride, bromide and iodide hydrosol particles were studied as freezing nuclei. Ice nucleation was enhanced through the exchange of iodine ions on the surface of solid silver iodide, using iodine monobromide. Drops containing AgI in concentrations larger than 10−4 gm cm−3 froze between −3 and −3.4C in the presence of iodine monobromide, supplied from the reaction between potassium iodide and N-bromosuccinimide. These results give support to Fukuta-Paik calculations showing that Ag+ sites in AgI are responsible for the enhancement of ice nucleability.
Abstract
The concentrations of both deuterium and water-insoluble particles in snow collected during snowstorms in the mountains of Colorado were found to be proportional to the size of snowflakes. Large snowflakes were associated with high particle concentration and high deuterium content. Small snow crystals appear to have originated in deuterium and aerosol-particle depleted air. The small snow crystals appeared at times of highest ice-forming nuclei concentration in air. The ratios of concentrations of different sized particles present in snow collected during a brief snowshower in March reveal that the predominant particles within small snow crystals are indeed those corresponding to the size range of ice nuclei. The relationship between the number of different sized particles present in a single snow crystal and the mass of snow crystals is given. Analyses of trajectories of moisture-bearing air parcels explained the large difference between the deuterium content of snow from the two snowfalls.
Abstract
The concentrations of both deuterium and water-insoluble particles in snow collected during snowstorms in the mountains of Colorado were found to be proportional to the size of snowflakes. Large snowflakes were associated with high particle concentration and high deuterium content. Small snow crystals appear to have originated in deuterium and aerosol-particle depleted air. The small snow crystals appeared at times of highest ice-forming nuclei concentration in air. The ratios of concentrations of different sized particles present in snow collected during a brief snowshower in March reveal that the predominant particles within small snow crystals are indeed those corresponding to the size range of ice nuclei. The relationship between the number of different sized particles present in a single snow crystal and the mass of snow crystals is given. Analyses of trajectories of moisture-bearing air parcels explained the large difference between the deuterium content of snow from the two snowfalls.
Abstract
Variable concentrations of different sized water-insoluble particles were found in bulk rainwater and single raindrops (liquid phase) and in hailstones (solid phase) collected from severe thunderstorms in the Colorado-Nebraska region. It was possible to draw the following conclusions from studies of aerosol particles transferred into the liquid phase of the storm: 1) aerosol particles constitute an intrinsic part of a convective cloud in a severe thunderstorm; 2) the size distribution of cloud droplets is extended to larger sizes by thepresence of giant aerosol particles (> 75 n diameter); 3) giant aerosol particles begin to accrete cloud droplets as soon as they enter the cloud; and 4) the size distribution of raindrops falling at the leading edge of a severe storm depends on the concentration of giant aerosol particles ingested by the storm.
The presence of different sized particles in the solid phase led to the following conclusions: 1) transparenthailstones are formed from the frozen Equid phase of a cloud (cloud droplets and raindrops) around giantaerosol particles, some of the giant aerosol particles acting as ice-forming nuclei at temperatures as warmas - 6C; 2) milky hailstones originate in the presence of ice crystals which have grown through the liquid-vapor-solid phase transition; 3) the majority of ice-forming nuclei in milky hailstones are particles between6 and 12 y. diameter, this size range being the result of particle separation by size in an ascending cloud; and4) detailed analysis of particulate matter present in different forms of ice in mixed hailstones provides information on the environmental conditions during their formation and growth.
A numerical model shows possible conditions for the formation of raindrops around giant aerosol particles. The models calculations also predict strong separation of different sized aerosol particles ingested by the storm. The latter was verified in samples from a storm in which rainfall contained no 50-75 μ diameterparticles, while hailstones contained up to 2300 particles in the same size range, per gram of ice.
Abstract
Variable concentrations of different sized water-insoluble particles were found in bulk rainwater and single raindrops (liquid phase) and in hailstones (solid phase) collected from severe thunderstorms in the Colorado-Nebraska region. It was possible to draw the following conclusions from studies of aerosol particles transferred into the liquid phase of the storm: 1) aerosol particles constitute an intrinsic part of a convective cloud in a severe thunderstorm; 2) the size distribution of cloud droplets is extended to larger sizes by thepresence of giant aerosol particles (> 75 n diameter); 3) giant aerosol particles begin to accrete cloud droplets as soon as they enter the cloud; and 4) the size distribution of raindrops falling at the leading edge of a severe storm depends on the concentration of giant aerosol particles ingested by the storm.
The presence of different sized particles in the solid phase led to the following conclusions: 1) transparenthailstones are formed from the frozen Equid phase of a cloud (cloud droplets and raindrops) around giantaerosol particles, some of the giant aerosol particles acting as ice-forming nuclei at temperatures as warmas - 6C; 2) milky hailstones originate in the presence of ice crystals which have grown through the liquid-vapor-solid phase transition; 3) the majority of ice-forming nuclei in milky hailstones are particles between6 and 12 y. diameter, this size range being the result of particle separation by size in an ascending cloud; and4) detailed analysis of particulate matter present in different forms of ice in mixed hailstones provides information on the environmental conditions during their formation and growth.
A numerical model shows possible conditions for the formation of raindrops around giant aerosol particles. The models calculations also predict strong separation of different sized aerosol particles ingested by the storm. The latter was verified in samples from a storm in which rainfall contained no 50-75 μ diameterparticles, while hailstones contained up to 2300 particles in the same size range, per gram of ice.
Abstract
A field technique was developed to detect silver iodide seeding agent in snow samples. The technique consists of collecting snow during a snow storm, forming liquid drops by melting pellets made from the snow, and refreezing the drops. A histogram of frequency of drop freezing plotted against temperature indicates the presence or absence of silver iodide in snow.
Abstract
A field technique was developed to detect silver iodide seeding agent in snow samples. The technique consists of collecting snow during a snow storm, forming liquid drops by melting pellets made from the snow, and refreezing the drops. A histogram of frequency of drop freezing plotted against temperature indicates the presence or absence of silver iodide in snow.
