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Information about Noctilucent Cloud

Enlarge picture
Noctilucent clouds over Lake Saimaa.
Noctilucent clouds over Lake Saimaa.
AbbreviationNLC/PMC
Altitude85,000 m
(300,000 ft)
ClassificationOther
Precipitation Cloud?No


Noctilucent clouds, also known as polar mesospheric clouds, are bright cloudlike atmospheric phenomena visible in a deep twilight. The name means roughly "night shining" in Latin. They are most commonly observed in the summer months at latitudes between 50° and 70° north and south of the equator.

They are the highest clouds in the Earth's atmosphere, located in the mesosphere at altitudes of around 85 km, and are visible only when illuminated by sunlight from below the horizon while the ground and lower layers of the atmosphere are in the Earth's shadow; otherwise they are too faint to be seen. Noctilucent clouds are a not fully understood meteorological phenomenon. Clouds generally are not able to reach such high altitudes, especially under such thin air pressures.

As an explanation, it was once proposed that they were composed of volcanic or meteoric dust, but they are now known to be primarily composed of water ice (confirmed by UARS). They appear to be a relatively recent phenomenon—they were first reported in 1885, shortly after the eruption of Krakatoa—and it has been suggested that they may be related to climate change. At least one researcher, Dr. Michael Stevens of the United States Naval Research Laboratory, believes space shuttle exhaust may contribute to the formation of noctilucent clouds. Imaging has also shown that some debris clouds from various space disasters have been mistaken for noctilucent clouds. [1]

Noctilucent clouds can be studied from the ground, from space, and in situ by sounding rockets; they are too high to be reached by weather balloons. Noctilucent clouds were first detected from space by an instrument on the OGO-6 [2] satellite in 1972. More recently they have been extensively studied by the Swedish satellite Odin [3] launched in 2001. The AIM satellite mission, launched in 2007, is dedicated to research into noctilucent clouds.

On August 28, 2006, scientists with the Mars Express mission announced that they found clouds of carbon dioxide similar to noctilucent clouds over Mars that extended up to 100 km above the surface of the planet. [4]

See also

External links

Enlarge picture
Night-shining clouds 80 kilometers above Earth's surface. Image data from the Aeronomy of Ice in the Mesosphere (AIM) satellite, NASA.
Location southeastern Finland
Coordinates Coordinates:


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1 metre =
SI units
1000 mm 0 cm
US customary / Imperial units
0 ft 0 in
The metre or meter[1](symbol: m) is the fundamental unit of length in the International System of Units (SI).
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1 foot =
SI units
0 m 0 mm
US customary / Imperial units
0 yd 0 in
A foot (plural: feet or foot;[1] symbol or abbreviation: ft or, sometimes, ′
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Luminosity has different meanings in several different fields of science.

In photometry and color imaging

Main article: luminance
In photometry, luminosity
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cloud is a visible mass of condensed droplets, frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body, such as a moon. (Clouds can also occur as masses of material in interstellar space, where they are called interstellar clouds and
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atmosphere is a layer of gases that may surround a material body of sufficient mass.[1] The gases are attracted by the gravity of the body, and are retained for a longer duration if gravity is high and the atmosphere's temperature is low.
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Twilight is the time before sunrise or after sunset when sunlight scattered in the upper atmosphere illuminates the lower atmosphere and the surface of the Earth is between light and dark.
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Latin}}} 
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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equator divides the planet into a Northern Hemisphere and a Southern Hemisphere, and has a latitude of 0. Latitude, usually denoted symbolically by the Greek letter phi, , gives the location of a place on Earth north or south of the equator.
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equator is an imaginary line on the Earth's surface equidistant from the North Pole and South Pole. It thus divides the Earth into a Northern Hemisphere and a Southern Hemisphere. The equators of other planets and astronomical bodies are defined analogously.
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cloud is a visible mass of condensed droplets, frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body, such as a moon. (Clouds can also occur as masses of material in interstellar space, where they are called interstellar clouds and
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Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly (by molar content/volume) 78% nitrogen, 20.95% oxygen, 0.93% argon, 0.
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mesosphere (from the Greek words mesos = middle and sphaira = ball) is the layer of the Earth's atmosphere that is directly above the stratosphere and directly below the thermosphere.
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KM, Km, or km may stand for:
  • Kappa Mikey, a animated series broadcasted on Nicktoons Network.
  • Kilometre (km)
  • Kernel methods
  • Kettle Moraine High School
  • Khmer language (ISO 639 alpha-2, km)
  • Kuomintang (KMT

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Meteorology (from Greek: μετέωρον, meteoron, "high in the sky"; and λόγος, logos, "knowledge") is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and
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For other uses see Altitude (disambiguation)


Altitude is the elevation of an object from a known level or datum (plural: data). Common data are mean sea level and the surface of the WGS-84 geoid, used by GPS.
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Volcanic ash consists of very fine rock and mineral particles less than 2 mm in diameter that are ejected from a volcanic vent. Ash is created when solid rock shatters and magma separates into minute particles during explosive volcanic activity.
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METEOR (Metric for Evaluation of Translation with Explicit ORdering) is a metric for the evaluation of machine translation output. The metric is based on the harmonic mean of unigram precision and recall, with recall weighted higher than precision.
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ICE may refer to:
  • Internal combustion engine, a fuel engine
  • In case of emergency, the emergency contact program created after the 7 July 2005 London Bombings
  • International Cometary Explorer, a former spacecraft
  • Integrated Collaboration Environment


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The Upper Atmosphere Research Satellite (UARS) is an orbital observatory whose mission is to study the Earth’s atmosphere, particularly the protective ozone layer.
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18th century - 19th century - 20th century
1850s  1860s  1870s  - 1880s -  1890s  1900s  1910s
1882 1883 1884 - 1885 - 1886 1887 1888

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Subjects:     Archaeology - Architecture -
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KRAKATOA is a modular explosive device used for explosive ordnance disposal (EOD) or demolitions. It was developed by the British company Alford Technologies and has been featured during the second season of Discovery Channel's Future Weapons television series.
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Climate change refers to the variation in the Earth's global climate or in regional climates over time. It describes changes in the variability or average state of the atmosphere over time scales ranging from decades to millions of years.
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Motto
"In God We Trust"   (since 1956)
"E Pluribus Unum"   ("From Many, One"; Latin, traditional)
Anthem
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United States Naval Research Laboratory (NRL) is the corporate research laboratory for the United States Navy and the United States Marine Corps and conducts a broad program of scientific research and advanced development.
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Space Shuttle

Space Shuttle Atlantis on the launch pad prior to the STS-115 mission.
Fact sheet
Function Manned partially re-usable launch and reentry system
Manufacturer United Space Alliance:
Thiokol/Boeing (SRBs)
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A sounding rocket, sometimes called a research rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight.
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weather or sounding balloon is a balloon which carries instruments aloft to send back information on atmospheric pressure, temperature, and humidity by means of a small, expendable measuring device called a radiosonde.
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Ogo can mean:
  • the on-the-go handheld device
  • Ogo, Senegal
  • the Orbiting Geophysical Observatory
  • OpenGroupware.org

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Odin is a Swedish satellite working in two disciplines; astrophysics and aeronomy. Within the field of astrophysics, Odin is used in the study of star formation. When used for aeronomical observations, it is the ozone layer depletion and effects of global warming that are explored.
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