|
James Chappuis
Louis Philibert Claude James Chappuis (born 10 November 1854 in Besançon; died 29 January 1934 in Paris) was a French chemist and physicist. Life Chappuis was the son of philosophy teacher Charles Chappuis (1822–1897, lived from 1845 to 1869 in Besançon) and Louise Lydie Berthot (died 1909), a granddaughter of Nicolas Berthot, a mathematician in Dijon. He attended schools in Besançon, Caen and Grenoble. He enrolled in the École normale supérieure (ENS) in Paris in 1874, then worked as a physics teacher at Montauban in 1877, and at Poitiers in 1878. He returned to Paris and was a Maître de conférences at the ENS from 1878 to 1882, passing the Agrégé in 1879. In 1881, he was appointed as Professor of Physics at the École centrale des arts et manufactures, and attained the doctoral degree in 1882 with a thesis on the spectroscopy of ozone. He led the research laboratory of the ''Societé du Gaz de Paris''. Chappuis is interred in the family tomb in Chailly-sur-Arm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Besançon
Besançon (, , , ; archaic german: Bisanz; la, Vesontio) is the prefecture of the department of Doubs in the region of Bourgogne-Franche-Comté. The city is located in Eastern France, close to the Jura Mountains and the border with Switzerland. Capital of the historic and cultural region of Franche-Comté, Besançon is home to the Bourgogne-Franche-Comté regional council headquarters, and is an important administrative centre in the region. It is also the seat of one of the fifteen French ecclesiastical provinces and one of the two divisions of the French Army. In 2019 the city had a population of 117,912, in a metropolitan area of 280,701, the second in the region in terms of population. Established in a meander of the river Doubs, the city was already important during the Gallo-Roman era under the name of ''Vesontio'', capital of the Sequani. Its geography and specific history turned it into a military stronghold, a garrison city, a political centre, and a religiou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johann Christian Poggendorff
Johann Christian Poggendorff (29 December 1796 – 24 January 1877), was a German physicist born in Hamburg. By far the greater and more important part of his work related to electricity and magnetism. Poggendorff is known for his electrostatic motor which is analogous to Wilhelm Holtz's electrostatic machine. In 1841 he described the use of the potentiometer for measurement of electrical potentials without current draw. Biography Poggendorf had apprenticed himself to an apothecary in Hamburg, and when twenty-two began to earn his living as an apothecary's assistant at Itzehoe. Ambition and a strong inclination towards a scientific career led him to throw up his business and move to Berlin, where he entered Humboldt University in 1820. Here his abilities were speedily recognized, and in 1823 he was appointed meteorological observer to the Academy of Sciences. Even at this early period he had conceived the idea of founding a physical and chemical scientific journal, and the real ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In Utero
''In Utero'' is the third and final studio album by American rock band Nirvana. It was released on September 21, 1993, by DGC Records. After breaking into the mainstream with their second album, ''Nevermind'' (1991), Nirvana hired Steve Albini to record ''In Utero'', seeking a more complex, abrasive sound that was also reminiscent of their debut album, ''Bleach'' (1989). Frontman Kurt Cobain took heavy inspiration from his personal struggles for the album's lyrics, many of which express feelings of angst that were common on ''Nevermind''. The album was recorded over two weeks in February 1993 at Pachyderm Studio in Cannon Falls, Minnesota. Soon after recording began, rumors circulated that DGC might not release the album due to Albini's abrasive and uncommercial sound. In response, the label hired producer Scott Litt to remix the singles " All Apologies", " Heart-Shaped Box" and " Pennyroyal Tea", upsetting both Albini and the band. ''In Utero'' was a major commercial and c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray
X-rays (or rarely, ''X-radiation'') are a form of high-energy electromagnetic radiation. In many languages, it is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it in 1895 and named it ''X-radiation'' to signify an unknown type of radiation.Novelline, Robert (1997). ''Squire's Fundamentals of Radiology''. Harvard University Press. 5th edition. . X-ray wavelengths are shorter than those of ultraviolet rays and longer than those of gamma rays. There is no universally accepted, strict definition of the bounds of the X-ray band. Roughly, X-rays have a wavelength ranging from 10 nanometers to 10 picometers, corresponding to frequencies in the range of 30 petahertz to 30 exahertz ( to ) and photon energies in the range of 100 eV to 100 keV, respectively. X-rays can penetrate many solid substances such as construction materials and living tissue, so X-ray radiography is widely used in medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crookes Tube
A Crookes tube (also Crookes–Hittorf tube) is an early experimental electrical discharge tube, with partial vacuum, invented by English physicist William Crookes and others around 1869-1875, in which cathode rays, streams of electrons, were discovered. Developed from the earlier Geissler tube, the Crookes tube consists of a partially evacuated glass bulb of various shapes, with two metal electrodes, the cathode and the anode, one at either end. When a high voltage is applied between the electrodes, cathode rays ( electrons) are projected in straight lines from the cathode. It was used by Crookes, Johann Hittorf, Julius Plücker, Eugen Goldstein, Heinrich Hertz, Philipp Lenard, Kristian Birkeland and others to discover the properties of cathode rays, culminating in J.J. Thomson's 1897 identification of cathode rays as negatively charged particles, which were later named '' electrons''. Crookes tubes are now used only for demonstrating cathode rays. Wilhelm Rö ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth's Shadow
Earth's shadow (or Earth shadow) is the shadow that Earth itself casts through its atmosphere and into outer space, toward the antisolar point. During the twilight period (both early dusk and late dawn), the shadow's visible fringe – sometimes called the dark segment or twilight wedge – appears as a dark and diffuse band just above the horizon, most distinct when the sky is clear. Since Earth's diameter is 3.7 times the Moon's, the length of the planet's umbra is correspondingly 3.7 times that of the lunar umbra: roughly . Appearance Earth's shadow cast onto the atmosphere can be viewed during the "civil" stage of twilight, assuming the sky is clear and the horizon is relatively unobstructed. The shadow's fringe appears as a dark bluish to purplish band that stretches over 180° of the horizon opposite the Sun, i.e. in the eastern sky at dusk and in the western sky at dawn. Before sunrise, Earth's shadow appears to recede as the Sun rises; after sunset, the sha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ozone Layer
The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer contains less than 10 parts per million of ozone, while the average ozone concentration in Earth's atmosphere as a whole is about 0.3 parts per million. The ozone layer is mainly found in the lower portion of the stratosphere, from approximately above Earth, although its thickness varies seasonally and geographically. The ozone layer was discovered in 1913 by the French physicists Charles Fabry and Henri Buisson. Measurements of the sun showed that the radiation sent out from its surface and reaching the ground on Earth is usually consistent with the spectrum of a black body with a temperature in the range of , except that there was no radiation below a wavelength of about 310&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Hour
The blue hour (from French ; ) is the period of twilight (in the morning or evening, around the nautical stage) when the Sun is at a significant depth below the horizon. During this time, the remaining sunlight takes on a mostly blue shade. This shade differs from the colour of the sky on a clear day, which is caused by Rayleigh scattering. The blue hour occurs when the Sun is far enough below the horizon so that the sunlight's blue wavelengths dominate due to the Chappuis absorption caused by ozone. Since the term is colloquial, it lacks an official definition such as dawn, dusk, or the three stages of twilight. Rather, blue hour refers to the state of natural lighting that usually occurs around the nautical stage of the twilight period (at dawn or dusk). Explanation and times of occurrence The still commonly presented incorrect explanation claims that Earth's post-sunset and pre-sunrise atmosphere solely receives and disperses the sun's shorter blue wavelengths and scat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Olson Hulburt
Edward Olson Hulburt (12 October 1890 – 11 October 1982) was an American geophysicist who studied the properties of the ionosphere and the color of the sky at the blue hour. Life and career Hulburt was born in Vermillion, South Dakota on 12 October 1890. He was educated at Johns Hopkins University, where his father was a professor of mathematics. He worked for 31 years at the United States Naval Research Laboratory, serving as head of the Physical Optics Division from 1929 to 1949, and Director of Research from 1949 to 1955. In 1926, he and Albert H. Taylor worked out several basic characteristics of the ionosphere, including the distribution of its electron density and dependence on solar elevation, by studying the propagation of radio signals in the atmosphere. They collaborated with Gregory Breit and Merle Tuve in the development of the ionosonde device used to study the ionosphere. Hulburt also studied how solar X-rays and extreme ultraviolet radiation were responsible f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rayleigh Scattering
Rayleigh scattering ( ), named after the 19th-century British physicist Lord Rayleigh (John William Strutt), is the predominantly elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation. For light frequencies well below the resonance frequency of the scattering particle (normal dispersion regime), the amount of scattering is inversely proportional to the fourth power of the wavelength. Rayleigh scattering results from the electric polarizability of the particles. The oscillating electric field of a light wave acts on the charges within a particle, causing them to move at the same frequency. The particle, therefore, becomes a small radiating dipole whose radiation we see as scattered light. The particles may be individual atoms or molecules; it can occur when light travels through transparent solids and liquids, but is most prominently seen in gases. Rayleigh scattering of sunlight in Earth's atmosphere cau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paul Hautefeuille
Paul Gabriel Hautefeuille (2 December 1836 in Étampes – 8 December 1902 in Paris) was a French mineralogist and chemist. Biography From 1855 he studied at the École Centrale des Arts et Manufactures in Paris. Later on, by way of a recommendation from Jean-Baptiste Dumas, he was admitted as an assistant to the laboratory of chemist Henri Sainte-Claire Deville at the École Normale Supérieure. In 1865 he earned his doctorates in physical sciences and medicine.Prosopo Sociétés savantes de France From 1870 to 1885, he served as co-director of the chemical laboratory at the École Normale Supérieure, and in 1876, he replaced as a lecturer ('' [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chappuis Absorption
Chappuis absorption () refers to the absorption of electromagnetic radiation by ozone, which is especially noticeable in the ozone layer, which absorbs a small part of sunlight in the visible portion of the electromagnetic spectrum. The Chappuis absorption bands occur at wavelengths between 400 and 650 nm. Within this range are two absorption maxima of similar height at 575 and 603 nm. Compared to the absorption of ultraviolet light by the ozone layer, known as the Hartley and Huggins absorptions, Chappuis absorption is distinctly weaker. Along with Rayleigh scattering, it contributes to the blue color of the sky, and is noticeable when the light has to travel a long path through the Earth's atmosphere. For this reason, Chappuis absorption only has a significant effect on the color of the sky at dawn and dusk, during the so-called blue hour. It is named after the French chemist James Chappuis (1854–1934), who discovered this effect. History James Chappuis was the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.JPG "Click for more on -> Besançon")
.jpg "Click for more on -> Blue Hour")
.jpg "Click for more on -> Rayleigh Scattering")
