Thule Scientific

Topanga, CA, United States

Thule Scientific

Topanga, CA, United States
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Richtsmeier S.C.,Spectral Sciences, Inc. | Lynch D.K.,Thule Scientific | Dearborn D.S.P.,Lawrence Livermore National Laboratory
Applied Optics | Year: 2017

For this paper, we employ the Monte Carlo scene (MCScene) radiative transfer code to elucidate the underlying physics giving rise to the structure and colors of the antitwilight, i.e., twilight opposite the Sun. MCScene calculations successfully reproduce colors and spatial features observed in videos and still photos of the antitwilight taken under clear, aerosol-free sky conditions. Through simulations, we examine the effects of solar elevation angle, Rayleigh scattering, molecular absorption, aerosol scattering, multiple scattering, and surface reflectance on the appearance of the antitwilight. We also compare MCScene calculations with predictions made by the MODTRAN radiative transfer code for a solar elevation angle of +1°. © 2017 Optical Society of America.


Lynch D.K.,Thule Scientific | Dearborn D.S.P.,Lawrence Livermore National Laboratory
Applied Optics | Year: 2017

Theoretical and experimental studies show that water ice spheres can produce a rainbow in which the primary and secondary bows overlap. To our knowledge, no such natural "icebow" has ever been reported. © 2017 Optical Society of America.


Lynch D.K.,Thule Scientific | Dearborn D.S.P.,Lawrence Livermore National Laboratory | Richtsmeier S.C.,Spectral Sciences, Inc.
Applied Optics | Year: 2017

Time-lapse videos, still photos, visual observations, and theoretical studies were used to investigate the antitwilight, i.e., twilight opposite the Sun. Colors, brightnesses, and antitwilight features as a function of solar altitude were measured. Four roughly horizontal bands were identified and explained physically in terms of atmospheric geometry, the observer's line-of-sight, optical depth, refraction, and multiple scattering. Particular emphasis is placed on (1) the origin of the dark segment, (2) the rapid rising of the Belt of Venus with solar altitude, and (3) ray tracing light through the low atmosphere to understand refractive effects. New names are suggested for three of the four bands, and the new terminology is reconciled with earlier papers. © 2017 Optical Society of America.


Lynch D.K.,Thule Scientific | Dearborn D.S.P.,Lawrence Livermore National Laboratory | Lock J.A.,Cleveland State University
Applied Optics | Year: 2011

We present new observations of glitter and glints using short and long time exposure photographs and high frame rate videos. Using the sun and moon as light sources to illuminate the ocean and laboratory water basins, we found that (1) most glitter takes place on capillary waves rather than on gravity waves, (2) certain aspects of glitter morphology depend on the presence or absence of thin clouds between the light source and the water, and (3) bent glitter paths are caused by asymmetric wave slope distributions We present computer simulations that are able to reproduce the observations and make predictions about the brightness, polarization, and morphology of glitter and glints.We demonstrate that the optical catastrophe represented by creation and annihilation of a glint can be understood using both ray optics and diffraction theory. © 2011 Optical Society of America.


Lynch D.K.,U.S. Geological Survey | Hudnut K.W.,U.S. Geological Survey | Adams P.M.,Thule Scientific
Geomorphology | Year: 2013

New field observations, aerial surveys, LiDAR measurements and laboratory studies of mud samples (2006 to 2012) are reported of several formerly submerged fumarole complexes that are presently undergoing surface exposure as the Salton Sea level drops. Some remain submerged as of this writing (2012). The fumarole fields range in area from 1000 to ~50,000m2. They consist of hundreds of warm to boiling hot gryphons (mud volcanoes), salses (mud pots), and countless active gas vents. Unusually-shaped mud volcanoes in the form of vertical tubes with central vents were observed in many places. Since exposure began in ~2007, the surface morphology has changed dramatically, with a trend toward more and growing gryphons, larger mud pots and the development of sulfur vents. Chemical analysis of mud from several gryphons revealed the presence of the ammoniated sulfate minerals boussingaultite and lecontite among other more common sulfates. With other geothermal features, the fumaroles define a well-defined lineament marking the trace of a probable fault. A model for the development of gryphon morphology is presented. © 2013 Elsevier B.V.


Bernstein L.S.,Spectral Sciences, Inc. | Clark F.O.,Spectral Sciences, Inc. | Lynch D.K.,Thule Scientific
Astrophysical Journal | Year: 2013

We suggest that the diffuse interstellar bands (DIBs) arise from absorption lines of electronic transitions in molecular clusters primarily composed of a single molecule, atom, or ion ("seed"), embedded in a single-layer shell of H2 molecules. Less abundant variants of the cluster, including two seed molecules and/or a two-layer shell of H2 molecules, may also occur. The lines are broadened, blended, and wavelength-shifted by interactions between the seed and surrounding H 2 shell. We refer to these clusters as contaminated H2 clusters (CHCs). We show that CHC spectroscopy matches the diversity of observed DIB spectral profiles and provides good fits to several DIB profiles based on a rotational temperature of 10 K. CHCs arise from ∼centimeter-sized, dirty H2 ice balls, called contaminated H2 ice macro-particles (CHIMPs), formed in cold, dense, giant molecular clouds (GMCs), and later released into the interstellar medium (ISM) upon GMC disruption. Attractive interactions, arising from Van der Waals and ion-induced dipole potentials, between the seeds and H2 molecules enable CHIMPs to attain centimeter-sized dimensions. When an ultraviolet (UV) photon is absorbed in the outer layer of a CHIMP, it heats the icy matrix and expels CHCs into the ISM. While CHCs are quickly destroyed by absorbing UV photons, they are replenished by the slowly eroding CHIMPs. Since CHCs require UV photons for their release, they are most abundant at, but not limited to, the edges of UV-opaque molecular clouds, consistent with the observed, preferred location of DIBs. An inherent property of CHCs, which can be characterized as nanometer size, spinning, dipolar dust grains, is that they emit in the radio-frequency region. We also show that the CHCs offer a natural explanation for the anomalous microwave emission feature in the ∼10-100 GHz spectral region. © 2013. The American Astronomical Society. All rights reserved.


Lynch D.K.,Thule Scientific
Applied Optics | Year: 2015

New observations and analyses are presented of the opposition effect on mud cracks (mud polygons) on desert playas. The enhanced brightness of the surface near the antisolar point has been previously and correctly ascribed to two sources: shadow-hiding and coherent backscatter. The observations reported here suggest that a third optical mechanism influences the OE: some parts of the mud polygon are more strongly illuminated than others, depending on the angle of incidence of sunlight. This causes the areas facing the observer and the sun to be brighter than the rest of the polygon field. This mechanism, called "dilution," also should occur in all OEs. © 2014 Optical Society of America.


Lynch D.K.,Thule Scientific
Applied Optics | Year: 2015

The angular diameter of Snell's window as a function of maximumwave slope is calculated. For flat water the diameter is 97° and increases up to about 122° when the wave slope is about 16°. Steeper waves break and disrupt the smooth surface used in the analysis. Breaking waves produce a window almost 180° wide. The brightness of the dark area around Snell's window is heavily influenced by turbidity and upwelling radiation, especially in shallow water. © 2014 Optical Society of America.


Lynch D.K.,Thule Scientific
Applied Optics | Year: 2015

We investigate the brightness distribution in and around outdoor shadows (for a variety of sky conditions) using modeling and field measurements. The dominant factor influencing the brightness of a shadow is the solid angle subtended by the object blocking the Sun. Occulters at the zenith that subtend a small solid angle cast shadows that are bright and possess a nearly uniform brightness across their extent. Shadows from large occulters are much darker and their brightness varies considerably, being darkest at their centers. For nonzenith occulters, the proximal (nearest the Sun) side of the shadow is darker than the distal side and the shadow will be darkest beneath the center of the occulter. Occulters (e.g., tree or cloud) influence the brightness of sunlit portions near the shadow because they block part of the sky and reflect light into the shadow. The aureole has a significant influence on the brightness of shadow edges. Semi-analytic formulations for the brightness in shadows are presented, and analytic expressions in wells and tunnels are derived. © 2015 Optical Society of America.


Lynch D.K.,Thule Scientific
Applied Optics | Year: 2015

Scattering by microscopic particles renders virtually all dusty surfaces brighter than dust-free surfaces. Examples of surface brightening are demonstrated in the landscape and laboratory and explained theoretically using Mie theory calculations. The implications for landscape photography and remote sensing are discussed. © 2014 Optical Society of America.

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