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Solar Illuminance Constant
The solar constant (''GSC'') is a flux density measuring mean solar electromagnetic radiation (total solar irradiance) per unit area. It is measured on a surface perpendicular to the rays, one astronomical unit (au) from the Sun (roughly the distance from the Sun to the Earth). The solar constant includes radiation over the entire electromagnetic spectrum. It is measured by satellite as being 1.361 kilowatts per square meter (kW/m2) at solar minimum (the time in the 11-year solar cycle when the number of sunspots is minimal) and approximately 0.1% greater (roughly 1.362 kW/m2) at solar maximum. The solar "constant" is not a physical constant in the modern CODATA scientific sense; that is, it is not like the Planck constant or the speed of light which are absolutely constant in physics. The solar constant is an average of a varying value. In the past 400 years it has varied less than 0.2 percent.http://lasp.colorado.edu/home/sorce/data/tsi-data/ Total Solar Irradiance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Irradiance Spectrum 1992
Solar may refer to: Astronomy * Of or relating to the Sun ** Solar telescope, a special purpose telescope used to observe the Sun ** A device that utilizes solar energy (e.g. "solar panels") ** Solar calendar, a calendar whose dates indicate the position of the Earth on its revolution around the Sun * Solar Maximum Mission, a satellite * SOLAR (ISS), an observatory on International Space Station Music * "Solar" (composition), attributed to Miles Davis * ''Solar'' (Red Garland album), 1962 * ''Solar'' (Taeyang album), 2010 * ''Solar'', a 2011 album by Rubik * "Solar", a song by Northlane from ''Mesmer'', 2017 * SOLAR Records, a record label Geography * Solar (Spanish term), a type of urban site * Solar, County Antrim, Northern Ireland, United Kingdom * Solar, Erode, India * Solar, Iran, Iran Companies * Solar Entertainment Corporation, a Philippines television and radio media company * Solar TV, a former TV channel * Solar Television Network, Inc., a former name o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Faint Young Sun Paradox
The faint young Sun paradox or faint young Sun problem describes the apparent contradiction between observations of liquid water early in Earth's history and the astrophysical expectation that the Sun's output would be only 70 percent as intense during that epoch as it is during the modern epoch. The paradox is this: with the young sun's output at only 70 percent of its current output, early Earth would be expected to be completely frozenbut early Earth seems to have had liquid water and supported life. The issue was raised by astronomers Carl Sagan and George Mullen in 1972. Proposed resolutions of this paradox have taken into account greenhouse effects, changes to planetary albedo, astrophysical influences, or combinations of these suggestions. It turned out that the greenhouse gas carbon dioxide contributed most. Solar evolution Models of stellar structure, esp. the standard solar model were already sufficiently evolved at that time to predict a brightening: It is due to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samuel Pierpont Langley
Samuel Pierpont Langley (August 22, 1834 – February 27, 1906) was an American aviation pioneer, astronomer and physicist who Invention, invented the bolometer. He was the third secretary of the Smithsonian Institution and a professor of astronomy at the University of Pittsburgh, where he was the director of the Allegheny Observatory. Life Langley was born in Roxbury, Boston, on August 23, 1834. Langley attended Boston Latin School and graduated from English High School of Boston, after which he became an assistant in the Harvard College Observatory. He then moved to a job at the United States Naval Academy, ostensibly as a professor of mathematics. However, he was actually sent there to restore the Academy's small observatory. In 1867, he became the director of the Allegheny Observatory and a professor of astronomy at the University of Pittsburgh (then known as the Western University of Pennsylvania), a post he kept until 1891 even while he became the third Secretary of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mont Blanc
Mont Blanc (french: Mont Blanc ; it, Monte Bianco , both meaning "white mountain") is the highest mountain in the Alps and Western Europe, rising above sea level. It is the second-most prominent mountain in Europe, after Mount Elbrus, and it is the eleventh most prominent mountain summit in the world. It gives its name to the Mont Blanc massif which straddles parts of France, Italy and Switzerland. Mont Blanc's summit lies on the watershed line between the valleys of Ferret and Veny in Italy, and the valleys of Montjoie, and Arve in France. Ownership of the summit area has long been a subject of dispute between France and Italy. The Mont Blanc massif is popular for outdoor activities like hiking, climbing, trail running and winter sports like skiing, and snowboarding. The most popular climbing route to the summit of Mont Blanc is the Goûter Route, which typically takes two days. The three towns and their communes which surround Mont Blanc are Courmayeur in Aosta Valle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jules Violle
Jules Louis Gabriel Violle (16 November 1841 – 12 September 1923) was a French physicist and inventor. He is notable for having determined the solar constant at Mont Blanc in 1875, and, in 1881, for proposing a standard for luminous intensity, called the Violle, equal to the light emitted by 1 cm² of platinum at its melting point. It was notable as the first unit of light intensity that did not depend on the properties of a particular lamp. This was much larger than traditional measures such as candlepower, so the standard SI unit candela was originally defined in 1946 as 1/60 Violle. Throughout his life, Violle taught at several colleges including the University of Lyon and the Conservatoire des Arts et Métiers in Paris. He was one of the founders of the Institut d'optique théorique et appliquée and the École supérieure d'optique. He improved and invented a number of devices for measuring radiation, and determined the freezing and melting points of palladium. V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrheliometer
A pyrheliometer is an instrument for measurement of direct beam solar irradiance. Sunlight enters the instrument through a window and is directed onto a thermopile which converts heat to an electrical signal that can be recorded. The signal voltage is converted via a formula to measure watts per square metre. Standards Pyrheliometer measurement specifications are subject to International Organization for Standardization (ISO) and World Meteorological Organization (WMO) standards. Comparisons between pyrheliometers for intercalibration are carried out regularly to measure the amount of solar energy received. The aim of the International Pyrheliometer Comparisons, which take place every 5 years at the World Radiation Centre in Davos, is to ensure the world-wide transfer of the World Radiometric Reference. During this event, all participants bring their instruments, solar-tracking and data acquisition systems to Davos to conduct simultaneous solar radiation measurements with the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Claude Pouillet
Claude Servais Mathias Pouillet (16 February 1790 – 14 June 1868) was a French physicist and a professor of physics at the Sorbonne and member of the French Academy of Sciences (elected 1837). Biography He studied sciences at the École normale supérieure (Paris), and from 1829 to 1849 was associated with the Conservatoire national des arts et métiers, first as a professor, and beginning in 1832, an administrator. After the death of Pierre Louis Dulong in 1838, he attained the chair of physics at the Faculty of Sciences.Biographical Encyclopedia of Astronomers edited by Virginia Trimble, Thomas R. Williams, K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Variation
The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surface. Over the period of a solar cycle, levels of solar radiation and ejection of solar material, the number and size of sunspots, solar flares, and coronal loops all exhibit a synchronized fluctuation from a period of minimum activity to a period of a maximum activity back to a period of minimum activity. The magnetic field of the Sun flips during each solar cycle, with the flip occurring when the solar cycle is near its maximum. After two solar cycles, the Sun's magnetic field returns to its original state, completing what is known as a Hale cycle. This cycle has been observed for centuries by changes in the Sun's appearance and by terrestrial phenomena such as aurora but was not clearly identified until 1843. Solar activity, driven by b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Langley (unit)
The langley (Ly) is a unit of heat transmission, especially used to express the rate of solar radiation (or insolation) received by the earth. The unit was proposed by Franz Linke in 1942 and named after Samuel Langley (1834–1906) in 1947. Definition One langley is *1 thermochemical calorie per square centimetre, *41 840 J/m2 (joules per square metre) See also * Solar constant * Radiant exposure In radiometry, radiant exposure or fluence is the radiant energy ''received'' by a ''surface'' per unit area, or equivalently the irradiance of a ''surface,'' integrated over time of irradiation, and spectral exposure is the radiant exposure per ... References Units of measurement Non-SI metric units {{electronics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Unit
The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits the Sun, from a maximum (aphelion) to a minimum (perihelion) and back again once each year. The astronomical unit was originally conceived as the average of Earth's aphelion and perihelion; however, since 2012 it has been defined as exactly (see below for several conversions). The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec. History of symbol usage A variety of unit symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union (IAU) had used the symbol ''A'' to denote a length equal to the astronomical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverse Square Law
In science, an inverse-square law is any scientific law stating that a specified physical quantity is inversely proportional to the square of the distance from the source of that physical quantity. The fundamental cause for this can be understood as geometric dilution corresponding to point-source radiation into three-dimensional space. Radar energy expands during both the signal transmission and the reflected return, so the inverse square for both paths means that the radar will receive energy according to the inverse fourth power of the range. To prevent dilution of energy while propagating a signal, certain methods can be used such as a waveguide, which acts like a canal does for water, or how a gun barrel restricts hot gas expansion to one dimension in order to prevent loss of energy transfer to a bullet. Formula In mathematical notation the inverse square law can be expressed as an intensity (I) varying as a function of distance (d) from some centre. The intensity is pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth's Atmosphere
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation). By mole fraction (i.e., by number of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere. Air composition, temperature, and atmospheric pressure vary with altitude. Within the atmosphere, air suitable for use in photosynthesis by terrestrial plants and breathing of terrestrial animals is found only in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
