Showing papers on "Haze published in 1987"

Dust storms and related phenomena measured from meteorological records in Australia

Abstract: Using meteorological records (1957–1984) in Australia, formal definitions are proposed of four types of dust event: dust storms, blowing dust, dust whirls, and dust haze. Australia-wide maps of the extent of these four dust event types are presented.

Nature of the stratospheric haze on Uranus: Evidence for condensed hydrocarbons

Abstract: The characteristics and origin of lower-stratosphere haze on Uranus are investigated on the basis of high-phase-angle images obtained at 430-600 nm with the wide-angle and narrow-angle cameras of Voyager 2 during its encounter with Uranus in January 1986. The data-reduction and model-fitting procedures are explained in detail, and the results are presented in extensive tables and graphs. The data are found to be best matched by a haze consisting of particles of modal radius 130 + or - 20 nm and number density 2 + or - 1 per cu cm at the 44-mbar level; such aerosols could be formed by the stratospheric condensation of photochemically produced hydrocarbon gases (locally formed diacetylene and ethane, acetylene, and diacetylene formed at higher altitudes). A total aerosol production rate of (2-15) x 10 to the -17th g/sq cm sec is estimated.

Observations of Saharan Aerosols: Results of ECLATS Field Experiment. Part I: Optical Thicknesses and Aerosol Size Distributions

Abstract: A series of ground-based and airborne observations of desert aerosols, the ECLATS experiment was carried out in December 1980 in the vicinity of Niamey (Niger). This paper deals with aerosol optical thicknesses and size distributions derived from (i) in situ measurements using singe particle optical counters (a Kratel and a Knollenberg FSSP), (ii) a ground-based cascade impactor, and (iii) ground-based measurements of the spectral variation of the sober extinction. During the experiment, aerosol optical thicknesses (at 550 nm) varied from 0.20 on very clear days to 1.5 during a so-called “dry haze” episode. Comparisons between size distributions derived from in situ measurements from ground-based cascade impactor, and from inversion of the spectral optical thicknesses, showed that the optical counters drastically underestimated the concentration of small (r<0.5 μm) particles It was shown that the occurrence of a “dry haze” episode was characterized by a large increase (an order of magnitude in th...

Interannual variability of global dust storms on Mars

Abstract: Global dust storms on Mars occur in some years but not in others. In years with global dust storms, dust is raised in the Southern Hemisphere and spread over much of the planet by an intensified Hadley circulation. In years without global dust storms, dust is raised in the Northern Hemisphere by relatively active midlatitude storm systems, but does not spread globally. In both cases the dusty season is winter in the north. It is shown from numerical simulations that a Northern Hemisphere dust haze weakens the intensity of the cross equatorial Hadley circulation and the contribution it makes to the surface stress in the Southern Hemisphere. This, in turn, reduces the possibility of global dust storm development. The interannual variability is the result either of a competition between circulation in opposite hemispheres, in which case the variability has a random component; or it is the result of the cycling of dust between hemispheres, in which case the variability is related to the characteristics of global dust storms themselves.

Chemically resolved submicrometric size distribution and external mixing of the Arctic haze aerosols

Abstract: Atmospheric aerosol particles were collected with filter and impactor samplers at Ny-Alesund, Spitzbergen during an Arctic haze event in the Spring of 1983. Additional integral aerosol parameters particle light scattering coefficient and total number concentration were also measured. The samples were analyzed for mass, elemental and soot content. With the exception of chlorine that was due to local marine sources, concentrations of the chemical species were all highly correlated with each other and with total mass concentration, light scattering and total number concentration. Mass concentration varied between 4 and 12 μg m -3 , other species showed values within the range reported previously under similar conditions. The impactor and total number concentration data were inverted to yield size distributions for the size range 0.01 to 1.0 μm radius. The mode of the total and elemental mass size distributions was in the range 0.13 to 0.26 μm with the exception of soot, which had a mode at slightly less than 0.13 μm. The main mass of the particulate material had hygroscopic properties similar to that previously observed for urban or continental aerosols. However, soot was observed to be associated with particles that were hygrophobic and it was concluded that it was externally mixed. Overall, the aerosol had properties indicative of one that had remained relatively unchanged after transport from its source region. DOI: 10.1111/j.1600-0889.1987.tb00200.x

Visual simulation of atmospheric haze

Abstract: For applications such as daylight visual pilot training simulators, the correct representation of aerial haze, mist and fog is of major importance in providing accurate depth cues and training in poor visibility conditions. We present a straightforward derivation of a formula to express this and then show various pictorial examples to illustrate its effectiveness.

The relationship between haze and the size of particles in beer

Abstract: Haze measurements have been obtained for suspensions of polystyrenelatex particles of known diameter using two light scattering instruments which measure at angles of 90° and 13° respectively. The results agree well with the theory of light scattering and demonstrate the significant effects of particle size and angle of detection upon the instrumental values for haze. This information has been used to correlate the particle size distributions of a number of beers, as measured by Coulter Counter, with the corresponding, measured haze values.

On radiative effects of anthropogenic aerosol components in Arctic haze and snow

Abstract: The Arctic aerosol is strongly enriched by anthropogenic pollution which may cause significant modifications of the Arctic climate. A radiation model with an optically interactive snow surface layer is developed to investigate the effect of anthropogenic elemental carbon (EC) and sulphuric acid in the Arctic atmosphere. The model, based on the delta-Eddington method, has 490 wavelength intervals covering solar and terrestrial radiation domains. Computations were made for aerosols-containing natural components and cases contaminated by anthropogenic EC and sulphuric acid, both categories with dry and moist conditions. Comparisons of model results with measurements in the Arctic of direct and total irradiance agree well. During mid-spring averaged conditions, the increase in the daily mean solar warming is found to be 2 or 3 times lower than earlier estimates. The previously expected surface cooling can be offset by direct to diffuse conversion in the haze and by snow contamination. In the infrared, the haze located in a temperature inversion can increase the upwelling irradiance by about 1%. This earth-atmosphere column cooling is caused by deliquescent aerosol material. In contrast, hygroscopic but non-deliquescent compounds like sulphuric acid result in internal exchange of radiative energy. In haze layers, the local cooling rate nearly offsets the daily averaged mid-spring local solar heating rate. More significant net warming due to EC particles takes place in dry and optically thin aerosol layers typically found above the Arctic boundary layer during pollution episodes. DOI: 10.1111/j.1600-0889.1987.tb00101.x

Chillproofing with magnesium silicate/silica gel agents

Abstract: Combinations of silica gel and magnesium silicate have been found to be effective agents to prevent the formation of haze in beer. Said haze, often called chill haze, is prevented by contacting the ruh beer with the combination to remove some or all of the components that react to form the haze. The spent combination is removed from the beer in the usual manner.

Multispectral Classification of Cloud, Fog and Haze

Abstract: This paper presents a method to derive images of different cloudtypes through a multispectral treatment of Advanced Very High Resolution Radiometer (AVHRR) imageries from the NOAA polar orbiting satellites. Four channels are included in the cloud analysis technique. Different problems appearing during winter and night time are discussed. Some results are presented.

Temperature and aerosol structure of the nightside Uranian stratosphere from Voyager 2 photopolarimeter stellar occultation measurements

Abstract: Voyager 2 UV-photopolarimeter occultation observations toward Gamma Peg, obtained on the nightside of Uranus at planetocentric latitude 68.9 deg N on January 24, 1986, are used to probe the structure of the Uranian atmosphere. The data are presented graphically and compared with the predictions of model atmospheres. The temperature profile for an aerosol-free atmosphere ranges from 85 + or - 2.3 K at 2.7 mbar to 96 + or - 13 K at 370 microbar, and the 1-mbar radius is found to be 25,219 + or - 6.3 km. The extinction coefficient for an aerosol haze layer at 1 mbar or higher is shown to be less than or equal to about 0.0001/km, but it is suggested that a well-mixed haze layer consisting of meteor or ring dust and/or photochemical condensates may well be present below 3 mbar.

Millimeter-wave studies of moist air

Abstract: : The near-millimeter region of the spectrum (NMMW: 0.1-1 THz) is an active area for research. Possible applications lie in short-range communications, radar, radiometry, and radio astronomy. Atmospheric effects of transmission and emission dominate performance simulations and the complex refractivity N provides a measure of the interactions between radiation and the atmospheric propagation medium. A reliable N-model allows calculation of frequency-dependent rates for delay (real part) and attenuation (imaginary part) based on measurable meteorological variables. Dry air and atmospheric water vapor are major millimeter-wave absorbers; so are suspended droplets (haze, fog, cloud) and precipitation water drops that emanate from the vapor phase. Laboratory research and analytical studies have been conducted with the primary purpose of understanding NMMW attenuation and delay rates.

Historical Atmospheric Transmission Changes and Changes in Midwestern Air Pollution

Abstract: Measurements of haze, smoke, dust, and visibility in the midwest available from 1901 to 1980 reveal sizable temporal fluctuations. These appear useful as surrogates of air pollutants not measured before 1950. Their historical record reflects both fluctuations in climate conditions and changing sources of major pollutants (such as the shift from coal to oil or gas as the primary fuels during 1950s, and the regionally extensive vehicular traffic that had become a major pollutant source since World War II). Regional uniformity found since the 1950s reflects integration of both area and point sources, and a general decrease of visibility from 1950 to 1970. Air quality regulations may have had little affect on haze, smoke, and dust except at very large cities where improvements in visibility have occurred since 1970.

Film for preventing glass from scattering

Abstract: PURPOSE:To improve the weatherability, resistance to piercing, glass scattering preventing effect and transparency of film by using a polyethylene naphthalate film which has breaking strength, surface haze and file haze or the sum of surface haze and internal haze of the film, respectively lying within specified ranges. CONSTITUTION:Polyethylene naphthalate film, the sum of the breaking strengths in longitudinal direction and in lateral direction on which is 45kg/mm or more, preferably 50kg/mm or more and more preferably 55kg/mm or more, is used. The above-mentioned film can be obtained by especially stretching in longitudinal direction and in lateral direction by the draw ratios of 300% or more, preferably 350% or more respectively or further stretching in longitudinal and/or lateral directions or the like. In addition; the surface haze of the film is to be 0.3-3% and the film haze which is the sum of the surface haze, and the internal haze of the film is to be 0.5-5% when converted to the thickness of 50mum. The workability of a film, the film haze of which is below 0.5%, deteriorates. On the contrary, a film, the film haze of which exceeds 5%, is poor in the transparency and the visual recognition of an object through said film becomes difficult.

Measuring the Water Content of Haze Particles

Abstract: The present work explores the use of a piezoelectric ten-stage cascade impactor that provides a near real time readout of mass collected at each stage. We present preliminary results for measuring the relative fraction of water present in atmospheric haze particles of different sizes under various real meteorological conditions.

Millimeter-wave attenuation and delay for a fog event

Abstract: Atmospheric propagation effects of suspended water droplets (SWD) representing haze, fog, or cloud conditions are modeled for frequencies f up to about 1000 GHz. The Rayleigh approximation is used to formulate SWD propagation effects and a double-Debye relaxation model is applied to predict frequency and temperature characteristics of the permittivity for water. Experimental results of fog attenuation and differential delay at 50.4, 81.8, 140.7, 245.5 GHz over a 0.81 km propagation path are applied to test the model.

Characterization of surficial units on Mars using Viking orbiter multispectral image and thermal data

Abstract: Albedo and thermal property correlations of the topography of Mars were conducted with emphases upon the types and origins of materials exposed in the central equatorial region This area displays a wide variation in color, albedo and thermal properties, and is relatively free of dust and haze The physical, mineralogical and elemental characteristics of this area are discussed

Spectral radiometry and tropospheric aerosols: Report of panel

Abstract: The term aerosols, as used here, refers to the haze, smoke, and dust that appear in the troposphere. The term does not refer to the hydrometeors in cumulus and stratus clouds but does include the sulfuric acid-water droplets which are assumed to predominate in the stratospheric aerosol layer. The aerosol properties that were measured from satellites and those which can be made in the near term (up to 1992) will be reviewed. The capabilities that will exist in the years 1992 to 2000, with implementation of EOS, are then discussed. Finally, a few words will be said concerning the potential for aerosol measurements for the decade after 2000.

On the effect of the coastal zone wind regime on the optical characteristics of haze

Abstract: Based on an experimental study of directed dissipation coefficients and aerosol microstructure in the coastal area the problem of wind regime manifestation is considered. It is shown that the main changes of parameters of dissipation indicatrix form near angles ϕ=15°–165°, which are conditioned by submicron fractions of aerosol particles, take place without regard for wind regime. Usually they are defined by effect of relative air humidity. It is found that specific manifestations of wind regime are observed close to small dissipation angles and are conditioned by the effect of coarse-dispersed aerosol fractions.