A Study on Polarization Pattern of Full Moonlight Based on the Neutral Points and the Meridian

2017 ◽  
Vol 868 ◽  
pp. 350-356 ◽  
Author(s):  
Yan Cui ◽  
Jin Yong Zhao ◽  
Jin Kui Chu ◽  
Le Guan ◽  
Ran Zhang
Keyword(s):  
Scattering Theory ◽  
Rayleigh Scattering ◽  
Imaging System ◽  
Neutral Point ◽  
Distribution Characteristics ◽  
Polarization Pattern ◽  
Clear Sky ◽  
Measured Polarization ◽  
Theory And Experiments

In order to provide the theory and experiments for the polarized skylight navigation, the polarization patterns of moonlight were discussed in this paper. The polarization patterns of moonlight were simulated by Matlab based on Rayleigh scattering theory. The polarization patterns of full moonlight were obtained by the full-sky imaging system in clear sky. The neutral point and the meridian contain the distribution characteristics of polarization patterns. Compared the tested results with the theoretical polarization patterns of moonlight, the neutral pointand the meridians of the measured polarization patterns of moonlight were studied. The results showed that the tested polarization patterns of moonlight were in agreement with the theoretical polarization patterns basically.

scholarly journals Mitos dan Eksplanasi Ilmiah Lembayung Senja

2018 ◽  
Vol 1 (1) ◽  
pp. 16
Author(s):  
Rahmat Rizal
Keyword(s):  
White Light ◽  
Scattering Theory ◽  
Rayleigh Scattering ◽  
Modern Society ◽  
Atmospheric Particles ◽  
Natural Phenomenon ◽  
The Sun ◽  
Scientific Explanations ◽  
Scattered Spectrum

A Violaceous sky attwilightis a natural phenomenon that occurs at sunset. This phenomenon is characterized by areddish yellow sky appearance. To explain this phenomenon, the community has developed a myth that connects the existence of the occult things such as the decline of the evil ghosts, witchcraft, and the epidemic of the disease. This myth has survived long enough in both sundanesse and Banjarmasin, South Kalimantan. The myth is spread in the community from mouth to mouth and occurs from generation to generation. Development of science and the changing minds of modern society effect myths that are present in society began to be degraded by scientific explanations reinforced by empirical evidences. The explanation used in explaining the twilight phenomenon uses the Hempel-Oppenheim explanation model. The explanationsare considered as general statementsconsidered correct. The Violaceous sky at twilight does not indicate the presence of ghosts, witches, or epidemics but it can be explained by Rayleigh scattering theory. The white light from the sun is dissipated by the atmospheric particles into the monochromatic spectrum. As a result of longer stages, the scattered spectrum has the longest wavelength

scholarly journals How the clear-sky angle of polarization pattern continues underneath clouds: full-sky measurements and implications for animal orientation

2001 ◽  
Vol 204 (17) ◽  
pp. 2933-2942 ◽  
Author(s):  
István Pomozi ◽  
Gábor Horváth ◽  
Rüdiger Wehner
Keyword(s):  
Single Scattering ◽  
Degree Of Polarization ◽  
Polarization Pattern ◽  
Clear Sky ◽  
Animal Navigation ◽  
Imaging Polarimetry ◽  
Polarization Compass ◽  
Sky Conditions ◽  
Perceptual Threshold ◽  
Animal Orientation

SUMMARY One of the biologically most important parameters of the cloudy sky is the proportion P of the celestial polarization pattern available for use in animal navigation. We evaluated this parameter by measuring the polarization patterns of clear and cloudy skies using 180° (full-sky) imaging polarimetry in the red (650nm), green (550nm) and blue (450nm) ranges of the spectrum under clear and partly cloudy conditions. The resulting data were compared with the corresponding celestial polarization patterns calculated using the single-scattering Rayleigh model. We show convincingly that the pattern of the angle of polarization (e-vectors) in a clear sky continues underneath clouds if regions of the clouds and parts of the airspace between the clouds and the earth surface (being shady at the position of the observer) are directly lit by the sun. The scattering and polarization of direct sunlight on the cloud particles and in the air columns underneath the clouds result in the same e-vector pattern as that present in clear sky. This phenomenon can be exploited for animal navigation if the degree of polarization is higher than the perceptual threshold of the visual system, because the angle rather than the degree of polarization is the most important optical cue used in the polarization compass. Hence, the clouds reduce the extent of sky polarization pattern that is useful for animal orientation much less than has hitherto been assumed. We further demonstrate quantitatively that the shorter the wavelength, the greater the proportion of celestial polarization that can be used by animals under cloudy-sky conditions. As has already been suggested by others, this phenomenon may solve the ultraviolet paradox of polarization vision in insects such as hymenopterans and dipterans. The present study extends previous findings by using the technique of 180° imaging polarimetry to measure and analyse celestial polarization patterns.

Turbid Underwater Polarization Patterns Considering Multiple Mie Scattering of Suspended Particles

2020 ◽  
Vol 86 (12) ◽  
pp. 737-743
Author(s):  
Haoyuan Cheng ◽  
Jinkui Chu ◽  
Ran Zhang ◽  
Lianbiao Tian ◽  
Xinyuan Gui
Keyword(s):  
Rayleigh Scattering ◽  
Field Measurements ◽  
Distribution Patterns ◽  
Suspended Particles ◽  
Mie Scattering ◽  
Polarization Pattern ◽  
Polarization Distribution ◽  
Water Turbidity ◽  
Influence Of Water ◽  
Mie Scattering Theory

It is still unclear how water turbidity affects the underwater polarization pattern. Current simulations only consider single Rayleigh scattering of water molecules and ignore multiple Mie scattering of suspended particles. In this study, a method based on a combination of Monte Carlo numerical simulation and Mie scattering theory is used to establish a model of the turbid underwater polarization distribution. Stokes vector and Mueller matrix are used to simulate the underwater polarization patterns within Snell's window. The distribution patterns and dynamic changes of the simulation are consistent with field measurements. The maximum depth that the polarization pattern can be maintained is calculated for different water types. The influence of water turbidity on polarization patterns is discussed. This model provides a tool for researchers to quantitatively analyze the distribution of turbid underwater polarization. In addition, the study is valuable for remote sensing and marine surveillance.

SCATTERING OF ELASTIC WAVES BY SMALL INHOMOGENEITIES

Geophysics ◽  
1960 ◽  
Vol 25 (3) ◽  
pp. 642-648 ◽  
Author(s):  
John W. Miles
Keyword(s):  
Shear Modulus ◽  
Elastic Wave ◽  
Wave Field ◽  
General Result ◽  
Elastic Waves ◽  
Isotropic Medium ◽  
Scattering Theory ◽  
Rayleigh Scattering ◽  
S Waves ◽  
Scattering Of Elastic Waves

Rayleigh scattering theory is extended to determine the perturbation on an arbitrarily prescribed elastic wave field produced by small inhomogeneities in an otherwise homogeneous, isotropic medium. The general result is applied to the specific problems of the scattering of both plane P- and S-waves. It is found that a change in compressibility acts at a distance as a simple source and a change in density as a dipole, as in the acoustical problem, while a change in shear modulus contributes both simple‐source and quadrapole fields.

scholarly journals Seasonal variations in brightness temperature for central Antarctica

1993 ◽  
Vol 17 ◽  
pp. 300-306 ◽  
Author(s):  
C.J. Van Der Veen ◽  
K. C. Jezek
Keyword(s):  
Radiative Transfer ◽  
Brightness Temperature ◽  
Scattering Theory ◽  
Rayleigh Scattering ◽  
Source Term ◽  
Radiative Properties ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Temperature Model ◽  
One Dimensional

The radiative-transfer model developed by Zwally (1977) is modified and coupled to a one-dimensional time-dependent temperature model, to calculate the seasonal variation in brightness temperature. By comparing this with observed records, the radiative properties of firn can be determined. By retaining scattering as a source term in the radiative transfer function, agreement between model-derived scattering and absorption coefficients and those calculated from the Mie/Rayleigh scattering theory can be obtained. The horizontal brightness temperature is not linked to the vertical one through a constant power reflection coefficient.

Third-harmonic Rayleigh scattering: theory and experiment

2005 ◽  
Vol 22 (11) ◽  
pp. 2402 ◽  
Author(s):  
Vladislav I. Shcheslavskiy ◽  
Solomon M. Saltiel ◽  
Alexey Faustov ◽  
Georgi I. Petrov ◽  
Vladislav V. Yakovlev
Keyword(s):  
Scattering Theory ◽  
Rayleigh Scattering ◽  
Third Harmonic ◽  
Theory And Experiment

Clear sky solar illuminance using visual band irradiance

2014 ◽  
Vol 25 (3) ◽  
pp. 11-19
Author(s):  
A. Nurick
Keyword(s):  
Experimental Data ◽  
Wavelength Range ◽  
Atmospheric Aerosols ◽  
Rayleigh Scattering ◽  
Ground Level ◽  
Climatic Conditions ◽  
Visible Range ◽  
Full Spectrum ◽  
Clear Sky ◽  
Sky Conditions

Solar illuminance may be quantified by applying relevant efficacy functions to available full spectrum ground irradiance. Alternatively, illuminance may be determined by applying the Photopic function to ground level irradiance spectra obtained from the terrestrial irradiance spectrum adjusted using relevant atmospheric absorption and scattering coefficients. The Photopic function has finite values in the wavelength range of 400 nm to 700 nm and is concentrated around a mean wavelength of 555 nm with irradiance at wavelengths close to 555 nm contributing to the major portion of illuminance. Calculation of ground level direct, diffuse and hence global illuminance is simplified as absorption of irradiance in the atmosphere by water vapour and uniformly mixed gases is negligible and may be ignored. It is shown that due to the small variations in the overall irradiance over wavelengths in the visible bandwidth combined with the concentration effect of the Photopic function in this wavelength range illuminance may be calculated, with good accuracy, using constant extinction functions for both direct and diffuse illuminance. Due to the concentration of illuminance by the Photopic function global illuminance data were also correlated with a simplified description of illuminance attenuation through the atmosphere based on the Beer-Lambert-Bouger Law using a single constant effective extinction coefficient which accounts for all extinction processes under clear sky conditions over the visible range of wavelengths. Constants used in extinction functions for solar irradiance due atmospheric aerosols were obtained by fitting experimental data to analytical descriptions of atmospheric extinction while published constants were used for ozone and Rayleigh scattering. The analytical descriptions of global illuminance with solar elevation were compared with experimental data collected at Johannesburg over both summer and winter clear sky conditions. Correlations of measured and calculated global illuminance data for the method based on extinction of various atmospheric components was 4.47 % and 4.49 % for the method based on the Beer-Lambert-Bouger Law, both normalised using the terrestrial illuminance constant. While measurements were made at a specific site in Gauteng, the methods used to correlate the data are general and location independent but local climatic conditions may need to be taken into account to quantify the extinction coefficients for specific areas.

Temperature Imaging of Vortex-Flame Interaction by Filtered Rayleigh Scattering

2003 ◽  
Author(s):  
Sean P. Kearney ◽  
Robert W. Schefer ◽  
Steven J. Beresh ◽  
Thomas W. Grasser
Keyword(s):  
Diffusion Flame ◽  
Rayleigh Scattering ◽  
Imaging System ◽  
Time Lag ◽  
Molecular Iodine ◽  
Attractive Alternative ◽  
Molecular Scattering ◽  
Single Vortex ◽  
Temperature Imaging ◽  
Full Field

This paper describes the application of a filtered-Rayleigh-scattering (FRS) instrument for nonintrusive temperature imaging in a vortex-driven diffusion flame. The FRS technique provides quantitative, spatially correlated temperature data without the flow intrusion or time lag associated with physical probes. Use of a molecular iodine filter relaxes the requirement for clean, particulate-free flowfields and offers the potential for imaging near walls, test section windows and in sooty flames, all of which are preculded in conventional Rayleigh imaging, where background interference from these sources typically overwhelms the weak molecular scattering signal. For combustion applications, FRS allows for full-field temperature imaging without chemical seeding of the flowfield, which makes FRS an attractive alternative to other laser-based imaging methods such as planar laser-induced fluorescencs (PLIF). In this work, the details of our FRS imaging system are presented and temperature measurements from an acoustically forced diffusion flame are provided. The local Rayleigh crosssection is corrected using Raman imaging measurements of the methane fuel molecule, which are then correlated to other major species using a laminar flamelet approach. To our knowledge, this is the first report of joint Raman/FRS imaging for nonpremixed combustion. Measurements are presented from flames driven at 7.5 Hz, where a single vortex stretches the flame, and at 90 Hz, where two consecutive vortices interact to cause a repeatable strain-induced flame-quenching event.

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