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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] |
Vermillion, South Dakota
Vermillion (; "The Place Where Vermilion is Obtained") is a city and the county seat of Clay County. It is in the southeastern corner of South Dakota, United States, and is the state's 12th-most populous city. According to the 2020 census, the population was 11,695. The city lies atop a bluff near the Missouri River. The area has been home to Native American tribes for centuries. French fur traders first visited in the late 18th century. Vermillion was founded in 1859 and incorporated in 1873. The name refers to the Lakota name: ''wa sa wak pa'la'' (red stream). Home to the University of South Dakota, Vermillion has a mixed academic and rural character: the university is a major academic institution for the state, with its only law and medical schools and its only AACSB-accredited business school. Major farm products include corn, soybeans, and alfalfa. History Lewis and Clark camped at the mouth of the Vermillion River near the present-day town on August 24, 1804. The previ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F Region
The F region of the ionosphere is home to the F layer of ionization, also called the Appleton–Barnett layer, after the English physicist Edward Appleton and New Zealand physicist and meteorologist Miles Barnett. As with other ionospheric sectors, 'layer' implies a concentration of plasma, while 'region' is the volume that contains the said layer. The F region contains ionized gases at a height of around 150–800 km (100 to 500 miles) above sea level, placing it in the Earth's thermosphere, a hot region in the upper atmosphere, and also in the heterosphere, where chemical composition varies with height. Generally speaking, the F region has the highest concentration of free electrons and ions anywhere in the atmosphere. It may be thought of as comprising two layers, the F1 and F2 layers. The F-region is located directly above the E region (formerly the Kennelly-Heaviside layer) and below the protonosphere. It acts as a dependable reflector of HF radio signals as it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Geophysicists
American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, people who self-identify their ancestry as "American" ** American English, the set of varieties of the English language native to the United States ** Native Americans in the United States, indigenous peoples of the United States * American, something of, from, or related to the Americas, also known as "America" ** Indigenous peoples of the Americas * American (word), for analysis and history of the meanings in various contexts Organizations * American Airlines, U.S.-based airline headquartered in Fort Worth, Texas * American Athletic Conference, an American college athletic conference * American Recordings (record label), a record label that was previously known as Def American * American University, in Washington, D.C. Sports teams S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1982 Deaths
Events January * January 1 – In Malaysia and Singapore, clocks are adjusted to the same time zone, UTC+8 (GMT+8.00). * January 13 – Air Florida Flight 90 crashes shortly after takeoff into the 14th Street bridges, 14th Street Bridge in Washington, D.C., United States, then falls into the Potomac River, killing 78 people. * January 14–17, 2022 North American winter storm, January 14 – An Ethiopian Air Force Antonov An-26 with an unknown registration crashed near Addis Ababa, Ethiopia, killing all 73 occupants on board. * January 18 – 1982 Thunderbirds Indian Springs Diamond Crash: Four Northrop T-38 aircraft of the United States Air Force crash at Indian Springs Air Force Auxiliary Field, Nevada, killing all 4 pilots. * January 26 – Mauno Koivisto is elected President of Finland. * January 27 – The government of Garret FitzGerald in Republic of Ireland, Ireland is defeated 82–81 on its budget; the 22nd Dáil is dissolved. * January 30 – The first computer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1890 Births
Events January * January 1 – The Kingdom of Italy establishes Eritrea as its colony in the Horn of Africa. * January 2 – Alice Sanger becomes the first female staffer in the White House. * January 11 – 1890 British Ultimatum: The United Kingdom demands Portugal withdraw its forces from the land between the Portuguese colonies of Portuguese Mozambique, Mozambique and Portuguese Angola, Angola (most of present-day Zimbabwe and Zambia). * January 15 – Ballet ''The Sleeping Beauty (ballet), The Sleeping Beauty'', with music by Pyotr Ilyich Tchaikovsky, Tchaikovsky, is premiered at the Mariinsky Theatre, Imperial Mariinsky Theatre in Saint Petersburg, St. Petersburg, Russia. * January 25 ** The United Mine Workers of America is founded. ** American journalist Nellie Bly completes her round-the-world journey in 72 days. February * February 5 – The worldwide insurance and financial service brand Allianz is founded in Berlin, Germany. * February 18 – The National Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Geophysical Union
The American Geophysical Union (AGU) is a 501(c)(3) nonprofit organization of Earth, Atmospheric science, atmospheric, Oceanography, ocean, Hydrology, hydrologic, Astronomy, space, and Planetary science, planetary scientists and enthusiasts that according to their website includes 130,000 people (not members). AGU's activities are focused on the organization and dissemination of scientific information in the interdisciplinary and international fields within the Earth and space sciences. The geophysical sciences involve four fundamental areas: atmospheric sciences, atmospheric and ocean sciences; solid-Earth sciences; hydrologic sciences; and space sciences. The organization's headquarters is located on Florida Avenue in Washington, D.C. History The AGU was established in December 1919 by the United States National Research Council, National Research Council (NRC) to represent the United States in the International Union of Geodesy and Geophysics (IUGG), and its first chairman w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Society Of America
Optica, founded as the Optical Society of America (later the Optical Society), is a professional society of individuals and companies with an interest in optics and photonics. It publishes journals, organizes conferences and exhibitions, and carries out charitable activities. History Optica was founded in 1916 as the Optical Society of America, under the leadership of Perley G. Nutting, with 30 optical scientists and instrument makers based in Rochester, New York. It soon published its first journal of research results and established an annual meeting. The group's ''Journal of the Optical Society of America'' was created in 1918. The first series of joint meetings with the American Physical Society took place in 1918. In 2008, it changed its name to the Optical Society. In September 2021, the organization's name changed to Optica, in reference to the organization's journal by the same name and geographic neutrality to reflect the society's global membership. In 2024, follow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Navy
The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 million tons in 2021. It has the world's largest aircraft carrier fleet, with List of aircraft carriers in service, eleven in service, one undergoing trials, two new carriers under construction, and six other carriers planned as of 2024. With 336,978 personnel on active duty and 101,583 in the Ready Reserve, the U.S. Navy is the third largest of the United States military service branches in terms of personnel. It has 299 deployable combat vessels and about 4,012 operational aircraft as of 18 July 2023. The U.S. Navy is one of six United States Armed Forces, armed forces of the United States and one of eight uniformed services of the United States. The United States Navy traces its origins to the Continental Navy, which was established during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rayleigh Scattering
Rayleigh scattering ( ) is the scattering or deflection of light, or other electromagnetic radiation, by particles with a size much smaller than the wavelength of the radiation. For light frequencies well below the resonance frequency of the scattering medium (normal dispersion relation, dispersion regime), the amount of scattering is inversely proportional to the fourth power of the wavelength (e.g., a blue color is scattered much more than a red color as light propagates through air). The phenomenon is named after the 19th-century British physicist Lord Rayleigh (John William Strutt). 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 throu ... [...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 wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
