Light Pillars and Diamond Dust in London Ontario Canada

A light pillar is an atmospheric optical

phenomenon A phenomenon ( : phenomena) is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influenced by Gottfried W ...

in which a vertical beam of light appears to extend above and/or below a

light source Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahe ...

. The effect is created by the

reflection Reflection or reflexion may refer to: Science and technology * Reflection (physics), a common wave phenomenon ** Specular reflection, reflection from a smooth surface *** Mirror image, a reflection in a mirror or in water ** Signal reflection, in ...

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...

from tiny

ice crystal Ice crystals are solid ice exhibiting atomic ordering on various length scales and include hexagonal columns, hexagonal plates, dendritic crystals, and diamond dust. Formation The hugely symmetric shapes are due to depositional growth, na ...

s that are suspended in the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

or that comprise high-altitude

clouds In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may com ...

(e.g.

cirrostratus Cirrostratus is a high-level, very thin, generally uniform ''stratiform'' genus-type of cloud. It is made out of ice-crystals, which are pieces of frozen water. It is difficult to detect and it can make halos. These are made when the cloud takes ...

cirrus cloud Cirrus ( cloud classification symbol: Ci) is a genus of high cloud made of ice crystals. Cirrus clouds typically appear delicate and wispy with white strands. Cirrus are usually formed when warm, dry air rises, causing water vapor deposition on ...

s).Colonne lumineuse
by the

World Meteorological Organization The World Meteorological Organization (WMO) is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. The WMO originated from the Internati ...

. If the light comes from the Sun (usually when it is near or even below the

horizon The horizon is the apparent line that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This line divides all viewing directions based on whether i ...

), the phenomenon is called a sun pillar or solar pillar. Light pillars can also be caused

by the Moon By or BY may refer to: Places * By, Doubs, France, a commune * By, Norway, a village Codes * Belarus ISO country code ** .by, country-code top-level domain for Belarus * Burundi FIPS Pub 10-4 and obsolete NATO digram country code * TUI Airwa ...

or terrestrial sources, such as

streetlight A street light, light pole, lamp pole, lamppost, street lamp, light standard, or lamp standard is a raised source of light on the edge of a road or path. Similar lights may be found on a railway platform. When urban electric power distribution ...

s and erupting

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...

es.

Formation

Since they are caused by the interaction of light with

ice crystals Ice crystals are solid ice exhibiting atomic ordering on various length scales and include hexagonal columns, hexagonal plates, dendritic crystals, and diamond dust. Formation The hugely symmetric shapes are due to depositional growth, na ...

, light pillars belong to the family of halos. The

crystals A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...

responsible for light pillars usually consist of flat,

hexagonal In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A '' regular hexagon'' has ...

plates, which tend to orient themselves more or less horizontally as they fall through the air. Each flake acts as a tiny

mirror A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...

which reflects

light sources This is a list of sources of light, the visible part of the electromagnetic spectrum. Light sources produce photons from another energy source, such as heat, chemical reactions, or conversion of mass or a different frequency of electromagnetic ener ...

which are appropriately positioned below it (See drawing), and the presence of flakes at a spread of altitudes causes the reflection to be elongated vertically into a column. The larger and more numerous the crystals, the more pronounced this effect becomes. More rarely, column-shaped crystals can cause light pillars as well. In very cold weather, the ice crystals can be suspended near the ground, in which case they are referred to as

diamond dust Diamond dust is a ground-level cloud composed of tiny ice crystals. This meteorological phenomenon is also referred to simply as ''ice crystals'' and is reported in the METAR code as IC. Diamond dust generally forms under otherwise clear or near ...

. Unlike a

light beam A light beam or beam of light is a directional projection of light energy radiating from a light source. Sunlight forms a light beam (a sunbeam) when filtered through media such as clouds, foliage, or windows. To artificially produce a light ...

, a light pillar is not physically located above or below the

. Its appearance as a vertical line is an

optical illusion Within visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual perception, percept that arguably appears to differ from reality. Illusions come in a wide v ...

, resulting from the collective

off the

; but only those that are in the common

vertical plane In astronomy, geography, and related sciences and contexts, a '' direction'' or ''plane'' passing by a given point is said to be vertical if it contains the local gravity direction at that point. Conversely, a direction or plane is said to be hor ...

, direct the light rays towards the observer (See drawing). This is similar to viewing a light source on a body of

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

. Ripples on the surface of the water reflect the light source in many directions, and those that happen to be aimed at the viewer, combine to form a bright line pointing toward the light source.

Images

File:Highexposure01.jpg, Light Pillars caused by artificial lights, over

North Bay Ontario North Bay is a city in Northeastern Ontario, Canada. It is the seat of Nipissing District, and takes its name from its position on the shore of Lake Nipissing. North Bay developed as a railroad centre, and its airport was an important military ...

, Canada File:FairbanksUAFLightPillars.jpg, Pillars from uncovered work lights above

University of Alaska Fairbanks The University of Alaska Fairbanks (UAF or Alaska) is a public land-grant research university in College, Alaska, a suburb of Fairbanks. It is the flagship campus of the University of Alaska system. UAF was established in 1917 and opened for cla ...

File:Sunset in Saguaro National Park.JPG, Sunset with prominent sun pillar near

Tucson , "(at the) base of the black ill , nicknames = "The Old Pueblo", "Optics Valley", "America's biggest small town" , image_map = , mapsize = 260px , map_caption = Interactive map ...

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

. File:Sun pillar and kitesurfers.jpg, Sun pillar in

San Francisco San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

. File:Light pillars over Laramie Wyoming in winter night.jpg, Light pillars on a winter night in Laramie,

Wyoming Wyoming () is a U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the south ...

. File:Light Pillars Stockholm, Sweden 20160106.JPG, Light Pillars during a cold January 2016 winter night in

Stockholm Stockholm () is the Capital city, capital and List of urban areas in Sweden by population, largest city of Sweden as well as the List of urban areas in the Nordic countries, largest urban area in Scandinavia. Approximately 980,000 people liv ...

, Sweden. File:Antarctic-light 112 hg.jpg, A lower sun pillar seen in the Antarctic. File:SunPillarOhioJan15.jpg, A sun pillar seen in

Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...

in January 2015. File:Diamond Dust Light Pillars, Rochester, NY 1993.png, Light Pillars in

Rochester, New York Rochester () is a City (New York), city in the U.S. state of New York (state), New York, the county seat, seat of Monroe County, New York, Monroe County, and the fourth-most populous in the state after New York City, Buffalo, New York, Buffalo, ...

in the early morning hours of December 27, 1993. File:Light pillar from Western Europe 2019 Apr 4.jpg, Light pillar just after sunset from the Netherlands on April 4, 2019. File:Light pillar.jpg, alt=Light pillar in the Wasatch Mountains of Utah, Light pillar in the

Wasatch Mountains The Wasatch Range ( ) or Wasatch Mountains is a mountain range in the western United States that runs about from the Utah-Idaho border south to central Utah. It is the western edge of the greater Rocky Mountains, and the eastern edge of the G ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

File:Light Pillar Raubichi Belarus.jpg, Light Pillars in Raubichi, Belarus on a cold night in January. File:Light pillar in Lipetsk Russia.jpg, Light pillar in

Lipetsk Lipetsk ( rus, links=no, Липецк, p=ˈlʲipʲɪtsk), also romanized as Lipeck, is a city and the administrative center of Lipetsk Oblast, Russia, located on the banks of the Voronezh River in the Don basin, southeast of Moscow. Populatio ...

, Russia. File:Nocturnal Light Pillars.jpg, Nocturnal light pillars caused by light reflected through

ice fog Ice fog is a type of fog consisting of fine ice crystals suspended in the air. It occurs only in cold areas of the world, as water droplets suspended in the air can remain liquid down to . It should be distinguished from diamond dust, a precipi ...

Cambridge Bay Cambridge Bay (Inuinnaqtun: ''Iqaluktuuttiaq'' Inuktitut: ᐃᖃᓗᒃᑑᑦᑎᐊᖅ; 2021 population 1,760; population centre 1,403) is a hamlet located on Victoria Island in the Kitikmeot Region of Nunavut, Canada. It is the largest settl ...

Nunavut Nunavut ( , ; iu, ᓄᓇᕗᑦ , ; ) is the largest and northernmost Provinces and territories of Canada#Territories, territory of Canada. It was separated officially from the Northwest Territories on April 1, 1999, via the ''Nunavut Act'' ...

, Canada File:Mauna Loa light pillar.jpg, Light pillar produced by lava from

Mauna Loa Mauna Loa ( or ; Hawaiian: ; en, Long Mountain) is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaii in the Pacific Ocean. The largest subaerial volcano (as opposed to subaqueous volcanoes) in both mass and ...

in Hawaii during its 2022 eruption

References

External links

{{Commons, Sun pillar
Pillars
Atmospheric Optics. Explanations (10 pages) and many images.

An Introduction to Sun Pillars and Related Phenomena. The Weather Doctor's Weather Eyes. Another nice explanation, all on one page

– Sydney Morning Herald. November 1, 2006

NASA

Astronomy Picture of the Day Astronomy Picture of the Day (APOD) is a website provided by NASA and Michigan Technological University (MTU). According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written ...

, 15 December 2008 Atmospheric optical phenomena

Pillar A column or pillar in architecture and structural engineering is a structural element that transmits, through compression (physical), compression, the weight of the structure above to other structural elements below. In other words, a column i ...

Light sources

Formation

Images

See also

References

External links