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Light pillar

About: Light pillar is a(n) research topic. Over the lifetime, 52 publication(s) have been published within this topic receiving 176 citation(s). The topic is also known as: sun pillar & solar pillar.
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Journal ArticleDOI
Abstract: Numerical simulation of the nocturnal light pillar, an atmospheric optical phenomenon inadvertently caused by humans, reveals that the pillars are virtually completely polarized at the Brewster angle for ice as a result of the geometry of rays reflected off near-horizontally aligned ice crystals from a nearby light source. It is also shown for plate crystals that the first-order internal reflection contributes importantly to the display and that the depth of the crystal-containing layer and the effects of atmospheric attenuation serve to limit the height above the horizon to which the pillars are visible. The model findings have been verified with experiments involving the generation of artificial pillars from linearly polarized light sources. Both observations and model predictions support the view that the plate ice crystals causing the display have tilt angles that are distributed normally from the horizontal plane.

26 citations

Journal ArticleDOI
TL;DR: The light pollution model is employed to analyze spatial behavior of luminance at the night sky under cloudless and overcast conditions and discusses the discrepancies between sky luminance distributions when at first the planar light sources are considered and at second the point-source approximation is accepted.
Abstract: The light pollution model is employed to analyze spatial behavior of luminance at the night sky under cloudless and overcast conditions. Enhanced light excess is particularly identified at cloudy skies, because the clouds efficiently contribute to the downward luminous flux. It is evident that size of ground-based light sources can play an important role in the case of overcast sky conditions. Nevertheless, the realistically sized light sources are rarely embedded into light pollution modeling, and rather they are replaced by simple point sources. We discuss the discrepancies between sky luminance distributions when at first the planar light sources are considered and at second the point-source approximation is accepted. The found differences are noticeable if the size of the light source, distance to the observer, and altitude of a cloudy layer are comparable one to the other. Compared with point-source approximation, an inclusion of the size factor into modeling the light sources leads to partial elimination of the steep changes of sky luminance (typical for point sources of light). The narrow and sharp light pillars normally presented on the sky illuminated by point light sources can disappear or fuse together when two or more nearby light sources are considered with their real sizes. Sky elements situated close to the horizon will glow efficiently if luminous flux originates from two-dimensional ground-based entities (such as cities or villages).

24 citations

Hiroyuki Kojima1, Tomoko Ishiwata1, Takashi Ichijo1, Kozo Ogawa1, Yasuharu Takano1 
17 May 2004
Abstract: A road indication device is provided. The road-guidance indicating device has a light projection unit including light control means for controlling a lamp and light emitted from the lamp. The light projection unit project a light whose peak luminosity is 30000 cd or more, i.e., the light has a luminosity equal to or larger than a peak luminosity of a headlight of a car running on the road. Since a light pillar of light having a high light output and a thick light pillar is projected from the light projection unit, the visuality of the light pillar is improved even in the bad weather and the boundary between the driveway and the shoulder on the road can be affirmatively guided and indicated.

23 citations

29 Jul 2009
Abstract: The invention discloses a multifunctional environmental protection sunshine collection method, a device and application thereof. The multifunctional environmental protection sunshine collection method comprises the following steps: sunshine is highly compressed into an ultrahigh light pillar, after being cooled, the light pillar is sent into a spectrum separation and deployment storehouse and then the incident light is deployed, separated, combined, and the like; the ultra-intense visible light is led into a light pipe, optical lines are transmitted and then uniformly diffused. The invention has the advantages that according to statistics made by experts, electric consumption on daytime illumination occupies more than 40% of electric consumption on illumination, therefore, employing the multifunctional environmental protection sunshine collection device can use free sunshine light instead of electric light illumination during daytime; the device is the popularized, only China can save about 82 billion degrees of electricity per year, calculated as 0.8 Yuan per degree, 65.6 billion Yuan can be saved per year, besides, the device also has no pollution and can reduce the emission and pollution brought by generating electricity.

11 citations

03 Jan 2008
Abstract: The Path of Light.- The Reflection of Light.- Daguerreotypes: Light Captured.- The Refraction of Light.- Lenses: From Water Drops to Telescopes.- Sources of Light and Color.- Diffraction and Interference.- Rainbows.- Sea, Sky, and Cloud.- Polarized Light and Sunglasses.- Photons, Electrons, and the Atom.- X-rays, Ultraviolet Light, and Infrared.- X-ray Emission: Earth, Moon, and Mars.

11 citations

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