TY - CHAP A1 - Möllmann, Klaus-Peter A1 - Pinno, Frank A1 - Vollmer, Michael T1 - Influence of wind effects on thermal imaging results – Is the wind chill effect relevant ? T2 - In: InfraMation proceedings Vol. 8 (2007), 21-31 Y1 - 2007 SP - 21 EP - 31 ER - TY - JOUR A1 - Gedzelman, Stanley David A1 - Vollmer, Michael T1 - Atmospheric Optical Phenomena and Radiative Transfer JF - In: Bulletin of the American Meteorological Society. 89 (2008) 4, 471-485 N2 - We present simple radiative transfer models for the radiance and color of atmospheric optical phenomena. Skylight, halos, and rainbows are treated as singly scattered sunlight that is depleted by scattering as it passes through a plane-parallel atmosphere and a vertical rain shaft or a geometrically thin cloud layer. Skylight in a molecular atmosphere grades from deep blue at the zenith to pale blue near the horizon whenever the solar zenith angle sun ≤ 80°. Skylight near the horizon is orange resulting from wavelength-dependent scattering by air molecules and aerosol particles through a long oblique path through the atmosphere when the sun is low in the sky (sun ≥ 85°). Halos (and coronas) seen through clouds facing the sun are brightest for cloud optical depth τcld ≈ cos(sun), and fade to obscurity for τcld ≥ 5. Rainbows (and glories), seen by light that is backscattered from clouds, also appear most dramatic when 0.2 ≤ τcld ≤ 1, but remain visible even in the thickest clouds. Y1 - 2008 U6 - https://doi.org/10.1175/BAMS-89-4-471 SP - 471 EP - 485 ER - TY - JOUR A1 - Vollmer, Michael T1 - Effects of absorbing particles on coronas and glories JF - In: Applied optics 44 (2005) 27, 5658-5666 N2 - Light scattering from small particles changes if the particles are absorbing. Whereas the effect is small for coronas and Bishop's ring, glories show pronounced attenuation with increasing absorption. Results indicate suitable wavelength regions for studies of glory scattering from cloud tops. The behavior of core-shell particles could have applications for studying the atmosphere of Venus; in addition it provides more insight into the simple ray-path model of the glory. © 2005 Optical Society of America Y1 - 2005 U6 - https://doi.org/10.1364/AO.44.005658 SP - 5658 EP - 5666 ER - TY - CHAP A1 - Christmann, S. A1 - Vollmer, Michael T1 - Jahrgangsübergreifendes Projekt zum Wetter für die Grundschule T2 - In: Didaktik der Physik : Beiträge zur Frühjahrstagung Düsseldorf 2004 ; CD zur Frühjahrstagung des Fachverbandes Didaktik der Physik in der Deutschen Physikalischen Gesellschaft / V. Nordmeier ... (Hrsg.). - Berlin : Lehmanns Media, 2004. - 1 CD-ROM. - ISBN 3-86541-066-9 Y1 - 2004 ER - TY - JOUR A1 - Gedzelman, Stanley David A1 - Vollmer, Michael T1 - Crepuscular rays: laboratory experiments and simulations JF - In: Applied Optics Vol. 50 (2011) 28, pp. F142-F151 N2 - Model simulations of laboratory-generated and natural crepuscular rays are presented. Rays are created in the laboratory with parallel light beams that pass through artificial fogs and milk–water solutions. Light scattered by 90° in a dilute mixture of whole milk first increases in intensity with distance from the source to a maximum as a result of multiple scattering by mainly small angles before decreasing exponentially due to extinction as distance continues to increase. Crepuscular rays are simulated for three cloud configurations. In case 1, the Sun at the zenith is blocked by a cloud with an overhanging anvil. The rays appear white against blue sky and are brightest when atmospheric turbidity, β≈11 . Shading by the anvil separates maximum brightness from apparent cloud edge. In case 2, a ray passes through a rectangular gap in a cloud layer. The ray is faint blue in a molecular atmosphere but turns pale yellow as β and solar zenith angle, ϕsun , increase. At ϕsun=60° it appears most striking when the cloud is optically thick, β≈5 , and the beam width Δx≈1000 m . In these cases, increasing aerosol radius, raer , to about 1000 nm brightens, narrows, and shortens rays. In case 3, the twilight Sun is shaded by a towering cloud or mountain. The shaded rays are deeper blue than the sunlit sky because the light originates higher in the atmosphere, where short waves have suffered less depletion from scattering. The long optical path taken by sunlight at twilight makes color and lighting contrasts of the rays greatest when the air is quite clean, i.e., for β−1≪1 . In all cases, the brightest rays occur when sunlight passes through an optical thickness of atmosphere, τ≈O(1) . © 2011 Optical Society of America Y1 - 2011 U6 - https://doi.org/http://dx.doi.org/10.1364/AO.50.00F142 ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Rainbows, water droplets, and seeing—slow motion analysis of experiments in atmospheric optics JF - In: Applied optics Vol. 50 (2011) 28, pp. F21–F28 N2 - Many physics processes underlying phenomena in atmospheric optics happen on a rather short time scale such that neither the human eye nor video cameras are able to analyze the details. We report applications of high-speed imaging of laboratory experiments in atmospheric optics with subsequent slow motion analysis. The potential to study respective transient effects is investigated in general and for a few phenomena in detail, in particular for rainbow scattering due to single oscillating droplets during free fall, and for light propagation effects through atmospheric paths with turbulences, leading, e.g., to scintillation of stars or shimmering of mirage images. © 2011 Optical Society of America Y1 - 2011 U6 - https://doi.org/http://dx.doi.org/10.1364/AO.50.000F21 SP - F21 EP - F28 ER - TY - CHAP A1 - Vollmer, Michael A1 - Pinno, Frank A1 - Möllmann, Klaus-Peter T1 - Measurements of sun and moon with IR cameras: effects of air mass T2 - In: InfraMation proceedings. - Vol. 11 ( 2010) , 57-74 Y1 - 2010 SP - 74 ER - TY - CHAP A1 - Möllmann, Klaus-Peter A1 - Pinno, Frank A1 - Vollmer, Michael T1 - Two-color or ratio thermal imaging - potentials and limits T2 - In: InfraMation proceedings. - Vol. 11 (2010), pp.41-56 Y1 - 2010 SP - 41 EP - 56 ER - TY - CHAP A1 - Pinno, Frank A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Improved sensitivity for blower door thermography using image subtraction T2 - In: InfraMation proceedings. - Vol. 11 (2010), p. 29-40 Y1 - 2010 SP - 29 EP - 40 ER - TY - CHAP A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - New book on IR imaging: the ultimate resource for all users T2 - In: InfraMation proceedings. - Vol. 11 (2010), pp 75-80 Y1 - 2010 SP - 75 EP - 80 ER -