scholarly journals Scattering of light by dust-free air, with artificial reproduction of the blue sky.—Preliminary note

1918 ◽  
Vol 94 (662) ◽  
pp. 453-459 ◽  
Keyword(s):  
Sea Level ◽  
Suspended Particles ◽  
Artificial Reproduction ◽  
Blue Colour ◽  
Foreign Matter ◽  
Preliminary Note ◽  
Scattering Of Light ◽  
Free Air

It is now well established that the luminosity and blue colour of the sky on very clear days and at considerable altitudes above the sea-level can almost be accounted for by the scattering of light by the molecules of air, without postulating suspended particles of foreign matter, such as were thought necessary by the earlier writers. This conclusion depends on the measured opacity of the atmosphere, deduced from observations such as those of Abbot and Fowle of the sun’s radiation at various zenith distances. The opacities measured at Mount Wilson for different wave-lengths are found to be nearly in agreement with what would be expected if scattering by the molecules were alone operative; leaving little room for the action of larger particles.

Distinctive properties of rock-forming blue quartz: inferences from a multi-analytical study of submicron mineral inclusions

2011 ◽  
Vol 75 (4) ◽  
pp. 2519-2534 ◽  
Author(s):  
W. Seifert ◽  
D. Rhede ◽  
R. Thomas ◽  
H.-J. Förster ◽  
F. Lucassen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Temperatures ◽  
Analytical Study ◽  
Rayleigh Scattering ◽  
Spatial Density ◽  
Blue Colour ◽  
Scattering Of Light ◽  
Geological Significance ◽  
Mineral Inclusions ◽  
Ti In Quartz

AbstractThe study discusses the mineralogical, geochemical and thermometric properties of rock-forming blue quartz from eight worldwide occurrences. Compared to non-blue quartz, blue quartz contains significant amounts of submicron-sized (1 μm—100 nm) and nanometre-sized (<100 nm) inclusions. Mica, ilmenite and rutile constitute the most abundant submicron-sized inclusions, and are formed probably by syngenetic precipitation in the boundary layer between quartz and melt (entrapment model). Nanometre-sized rutile possibly originated by epigenetic exsolution of Ti from the quartz structure (exsolution model). Rayleigh scattering of light by nano-particulate inclusions best explains the origin of the blue colour. Blue quartz is generally Ti-rich (∼100—300 ppm) and formed at high temperatures (∼700°C—900°C). The large number, and high spatial density, of tiny xenocrystic inclusions of Ti-bearing minerals make calculations of crystallization temperatures using the Ti-in-quartz thermometer unreliable. The geological significance of blue quartz remains obscure.

Longwave Radiation at the Cloud-Aerosol Transition Zone from Radiative Parameterizations in Weather Research and Forecasting Model (WRF)

2020 ◽  
Author(s):  
Babak Jahani ◽  
Josep Calbó ◽  
Josep-Abel González
Keyword(s):  
Transition Zone ◽  
Atmospheric Aerosol ◽  
Longwave Radiation ◽  
Suspended Particles ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Liquid Droplets ◽  
Mixing Ratios ◽  
Free Air ◽  
Weather Research

&lt;p&gt;There are conditions between cloudy and cloud-free air at which it is hard to define the suspended particles in the atmosphere either as a cloud or an atmospheric aerosol; it is called twilight or transition zone. This occurs when characteristics of the suspended particles are between those corresponding to a pure cloud and those corresponding to a pure atmospheric aerosol. However, in most meteorological and climate studies the condition of sky is assumed to be either cloudy (fully developed cloud) or cloud-free (dry aerosol), neglecting the transition zone. The present communication aims to show the uncertainties introduced by this simplified assumption in modeling longwave radiation. For this purpose, the parameterizations RRTMG, NewGoddard and FLG included in the Weather Research and Forecasting Model (WRF) version 4.0 were isolated from the whole model. These parameterizations were then used to perform a number of simulations under ideal &amp;#8220;cloud&amp;#8221; and &amp;#8220;aerosol&amp;#8221; modes, for different values of (i) cloud optical thicknesses resulting from different sizes of ice crystals or liquid droplets, cloud height, mixing ratios; and (ii) different aerosol optical thicknesses combined with various aerosol types. The differences in the resulting longwave radiative effects (RE) at the top of the atmosphere and at the Earth surface were analyzed. The primary results show: (1) the parameterization RRTMG is not capable of simulating the REs of the aerosols in the longwave region, (2) different assumptions of a situation corresponding to the transition zone lead to a mean relative uncertainty of about 170% in the estimated longwave irradiance at both top of the atmosphere and surface, (3) the absolute uncertainties observed in the surface downwelling irradiances are substantially greater than those relating to the upwelling irradiances at top of the atmosphere.&lt;/p&gt;

scholarly journals Scattering of light by solid substances

1919 ◽  
Vol 95 (672) ◽  
pp. 476-479 ◽  
Keyword(s):  
Optical Glass ◽  
Scattered Light ◽  
Plate Glass ◽  
Small Particles ◽  
Parallel Beam ◽  
Blue Colour ◽  
Scattering Of Light

The observations already published on scattering of light by gases and liquids naturally led on to an examination of the behaviour of solids in this respect. At the first trial it was found that glass scatters very freely, the scattered light being blue, and in many cases almost completely polarised. The observation is so easy that it must almost certainly have been made before, though I have not met with any mention of it. No special arrangements are necessary. If a narrow parallel beam, say 6 mm. diameter, from the condenser of an electric lantern, is allowed to traverse the interior of a block of glass, the scattered light along the track will be conspicuous. This is a ready method of demonstrating the scattering by small particles. Numerous specimens of plate glass and optical glass have been examined. These all show the scattering, though they differ among themselves in respect of intensity and completeness of polarisation. The depth and purity of the blue colour goes of course with the latter.

scholarly journals Structural Layers Origin Of The Blue Colour Reflections On The Wings Of The Junonia Orithya Madagascarensis

2016 ◽  
Vol 12 (24) ◽  
pp. 147
Author(s):  
Issaka Ouedraogo ◽  
Emmanuel Nanema ◽  
Bintou Ouedraogo ◽  
Alioune Ouedraogo ◽  
Priscilla Simonis ◽  
...  
Keyword(s):  
Reflectance Spectrum ◽  
Main Peak ◽  
Nanometer Scale ◽  
Blue Color ◽  
Artificial Reproduction ◽  
Blue Colour ◽  
Selective Reflection ◽  
Structural Coloration ◽  
Structural Nature

This article is devoted to the study of the structural layers origin of the blue reflections on the scales of the wings of the Junonia orithya madagascarensis, a butterfly of the Nymphalidae species. We proceed by spectrophotometry and scanning electron microscope (SEM) characterization of these layers to explain the origin of the blue color of the wings. We also made numerical calculations to simulate the structural nature of these layers which help to support the experimental results. Indeed, from the measurements using the spectrophotometer, a main peak of reflection was obtained at 483 nm. From our calculations results we get a 515 nm for the dominant length in reflection and 510 nm for the numerical reproduction of the reflectance spectrum, respectively. These results confirm that the multilayer structure is at the origin of the blue colour of the dorsal scales of the wings of the Junonia. A very thin membrane is responsible for it. This membrane diffuses sunlight at its upper and inner surface. Therefore, it is called structural coloration. It is possible to consider artificial reproduction for the multilayer through a process of deposits in order to manufacture materials at nanometer scale with selective reflection.

On: “The normal vertical gradient of gravity” by J. H. Karl (GEOPHYSICS, 48, 1011–1013).

Geophysics ◽  
1984 ◽  
Vol 49 (9) ◽  
pp. 1563-1563 ◽  
Author(s):  
C. J. Swain
Keyword(s):  
Sea Level ◽  
Gravity Data ◽  
Vertical Gradient ◽  
Practical Significance ◽  
Average Value ◽  
The Earth ◽  
Free Air ◽  
The Mean ◽  
Local Anomalies ◽  
Vertical Gradient Of Gravity

The implication of the author’s hypothesis, that the conventional free‐air correction factor is difficult to justify and can lead to large errors (e.g., 14 mGal from 300 m of topographic relief), would be very serious indeed for many interpretations of gravity data if it were true. He predicts a normal vertical gradient of 0.264 mGal/m near sea level, 14 percent lower than the conventional theoretical value. However, precise measurements of the free‐air gradient near sea level have been reported (Kuo et al., 1969) which differ by less than [Formula: see text] percent from the theoretical value; moreover these differences correlate with small local (isostatic) anomalies. My own observations at Leicester, England (elevation 100 m) and Nairobi (elevation 1 650 m) (made with students) also differ by less than [Formula: see text] percent from the theoretical values and again the differences correlate with small local anomalies. If these values represent the normal free‐air gradient, it would appear that the author’s analysis must be wrong. The formula he derives gives, correctly, the mean vertical gradient at some level over and within the Earth to a good approximation. This can be seen simply by considering the well‐known formulas for the gradient at a point within the Earth where the density is ρ [Formula: see text] and at a point outside the Earth [Formula: see text] and taking averages at this radius. However, the average value has no practical significance. It does not apply to any point on the Earth’s surface; it is merely a mean.

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

Microbulldozing and Microchiseling

1969 ◽  
Vol 27 ◽  
pp. 134-135
Author(s):  
J.N. Ramsey ◽  
D.P. Cameron ◽  
F.W. Schneider
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Material Handling ◽  
Microprobe Analysis ◽  
Foreign Matter ◽  
Specific Location ◽  
Potential Problems ◽  
Knoop Indenter ◽  
Scanning Electron ◽  
Microhardness Tester

As computer components become smaller the analytical methods used to examine them and the material handling techniques must become more sensitive, and more sophisticated. We have used microbulldozing and microchiseling in conjunction with scanning electron microscopy, replica electron microscopy, and microprobe analysis for studying actual and potential problems with developmental and pilot line devices. Foreign matter, corrosion, etc, in specific locations are mechanically loosened from their substrates and removed by “extraction replication,” and examined in the appropriate instrument. The mechanical loosening is done in a controlled manner by using a microhardness tester—we use the attachment designed for our Reichert metallograph. The working tool is a pyramid shaped diamond (a Knoop indenter) which can be pushed into the specimen with a controlled pressure and in a specific location.

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