Engineering topics
Publications and source records attributed to Kocmond, W. C..
Twenty-five instruments were tested, including size characterization devices and two Aitken counters. The test aerosols were supplied to the instruments by an on-line generation system, thereby eliminating the need for storage bags. Cloud condensation chambers and haze chambers are highlighted.
Air-jet mill has two modifications, particle channel and large-particle exhaust port.
A two-dimensional numerical model was used to investigate the formation of marine advection fog. The model predicts the evolution of potential temperature, horizontal wind, water vapor content, and liquid water content in a vertical cross section of the atmosphere as determined by vertical turbulent transfer and horizontal advection, as well as radiative cooling and drop sedimentation. The model is designed to simulate the formation, development, or dissipation of advection fog in response to transfer of heat and moisture between the atmosphere and the surface as driven by advection over horizontal discontinuities in the surface temperature. Results from numerical simulations of advection fog formation are discussed with reference to observations of marine fog. A survey of candidate fog or cloud microphysics experiments which might be performed in the low gravity environment of a shuttle-type spacecraft in presented. Recommendations are given for relatively simple experiments which are relevent to fog modification problems.
A field investigation of the microphysical and micrometeorological features of fogs occurring near Los Angeles and Vandenberg, California was conducted. Observations of wind speed and direction, temperature, dew point, vertical wind velocity, dew deposition, drop-size distribution, liquid water content, and haze and cloud nucleus concentration were obtained. These observations were initiated in late evening prior to fog formation and continued until the time of dissipation in both advection and radiation fogs. Data were also acquired in one valley fog and several dense haze situations. The behavior of these parameters prior to and during fog are discussed in detail. A two-dimensional numerical model was developed to investigate the formation and dissipation of advection fogs under the influence of horizontal variations in surface temperature. The model predicts the evolution of potential temperature, water vapor content, and liquid water content in a vertical plane as determined by vertical turbulent transfer and horizontal advection. Results are discussed from preliminary numerical experiments on the formation of warm-air advection fog and dissipation by natural and artificial heating from the surface.
A detailed study was made of the micrometeorological and microphysical characteristics of eleven valley fogs occurring near Elmira, New York. Observations were made of temperature, dew point, wind speed and direction, dew deposition, vertical wind velocity, and net radiative flux. In fog, visibility was continuously recorded and periodic measurements were made of liquid water content and drop-size distribution. The observations were initiated in late evening and continued until the time of fog dissipation. The vertical distribution of temperature in the lowest 300 meters and cloud nucleus concentration at several heights were measured from an aircraft before fog nucleus concentrations at several heights were measured from an aircraft before fog formation. A numerical model was developed to investigate the life cycle of radiation fogs. The model predicts the temporal evolution of the vertical distributions of temperature, water vapor, and liquid water as determined by the turbulent transfer of heat and moisture. The model includes the nocturnal cooling of the earth's surface, dew formation, fog drop sedimentation, and the absorption of infrared radiation by fog.
Measurements of the total nucleus concentration and cloud condensation nuclei (CCN) were acquired for several conditions representing both high normal and severe pollution levels for the Los Angeles Basin as well as clean filtered air. The data show that in filtered air there is a large photochemically induced increase in the total particle content within a few minutes after starting the lamp. The concentration of CCN remains near zero, until sufficient coagulation and condensation occurs on the smaller Aitken particles. The addition of gaseous pollutants to filtered air results in large increases in the photochemical production of both the cloud and Aitken nucleus concentration. Fogs were also generated under controlled, reproducible conditions in the cloud chamber and seeded with aerosols of various compounds which form monomolecular surface films at air-water interfaces. Visibility characteristics and droplet data were obtained. The data suggest that droplet growth on treated nuclei can be retarded but fog formation was not significantly altered by the chemical seeding.
Radiation fogs sampled at Los Angeles were found to possess low visibilities, high liquid water content (LWC), relatively small drops, narrow peaked drop-size distributions, and high concentrations of micron sized haze droplets. Typical characteristics of valley fogs observed at Elmira, N.Y., were low visibilities, moderately high LWC, low concentrations of haze droplets, and similar drop size distributions to those measured in Los Angeles. On the other hand, advection fogs observed in Vandenberg were characterized by less severe visibilities, low LWC, large drops in a broad drop-size distribution, and very low haze nucleus concentrations.
Warm fog seeding to determine potential of various sized and unsized hygroscopic chemicals for fog dissipation
Ground based and aerial seeding of warm fog with hygroscopic materials and computer modeling of fog response to seeding
Ground and aerial applications of hygroscopic particles in fog dispersal experiments
Visibility improvement in warm fog by seeding with micron size hygroscopic particles, noting results for NaCl
Warm fog and fog modification by seeding with salt particles
Theoretical modeling of fog modification by seeding with hygroscopic nuclei, climatic survey of fog frequency in Buffalo, New York, large scale laboratory experiments, and field tests
Visibility in warm fog produced in cloud chamber by seeding with sodium chloride particles, with application for aircraft landing clearance
Warm fog properties and fog modification by preseeding atmosphere with sodium chloride
Evaluation of fog seeding experiments in thermal diffusion chamber
Warm fog properties and fog modification concepts
Classification of fog nuclei, and determination of drop sizes and concentration in seeded and unseeded fogs