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Nautical Time Zones
Nautical time is a maritime time standard established in the 1920s to allow ships on high seas to coordinate their local time with other ships, consistent with a long nautical tradition of accurate celestial navigation. Nautical time divides the globe into 24 nautical time zones with hourly clock offsets, spaced at 15 degrees by longitudinal coordinate, with no political deviation. Nautical timekeeping dates back to the early 20th century as a standard way to keep time at sea, although it largely only applied to military fleets pre–World War 2. This time-keeping method is only used for radio communications and to account for slight inaccuracies that using Greenwich Mean Time (GMT) may lead to during navigation of the high seas. It is typically only used for trans-oceanic travel, as captains will often not change the timekeeping for short distances such as channels or inland seas. History of nautical time Establishment Prior to 1920, ships kept solar time on the high seas b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time Standard
A time standard is a specification for measuring time: either the rate at which time passes or points in time or both. In modern times, several time specifications have been officially recognized as standards, where formerly they were matters of custom and practice. An example of a kind of time standard can be a time scale, specifying a method for measuring divisions of time. A standard for civil time can specify both time intervals and time-of-day. Standardized time measurements are made using a clock to count periods of some period changes, which may be either the changes of a natural phenomenon or of an artificial machine. Historically, time standards were often based on the Earth's rotational period. From the late 18 century to the 19th century it was assumed that the Earth's daily rotational rate was constant. Astronomical observations of several kinds, including eclipse records, studied in the 19th century, raised suspicions that the rate at which Earth rotates is gradually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DUT (time)
DUT1 is a time correction equal to the difference between Universal Time ( UT1), which is defined by Earth's rotation, and Coordinated Universal Time (UTC), which is defined by a network of precision atomic clocks, with a precision of +/- 0.1s. :DUT1 = UT1 − UTC (with a precision of +/- 0.1s) UTC is maintained via leap seconds, such that DUT1 remains within the range −0.9 s < DUT1 < +0.9 s. The reason for this correction is partly that the rate of rotation of the Earth is not constant, due to and the redistribution of mass within the Earth, including its oceans and atmosphere, and partly because the (as now used for |
Time Scales
Time scale may refer to: *Time standard, a specification of either the rate at which time passes, points in time, or both *A duration or quantity of time: ** Orders of magnitude (time) as a power of 10 in seconds; **A specific unit of time A unit of time is any particular time interval, used as a standard way of measuring or expressing duration. The base unit of time in the International System of Units (SI), and by extension most of the Western world, is the second, defined as ... * Geological time scale, a scale that divides up the history of Earth into scientifically meaningful periods In astronomy and physics: *Dynamical time scale, in stellar physics, the time in which changes in one part of a body can be communicated to the rest of that body, or in celestial mechanics, a realization of a time-like argument based on a dynamical theory *Nuclear timescale, an estimate of the lifetime of a star based solely on its rate of fuel consumption *Thermal time scale, an estima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horology
Chronometry or horology () is the science studying the measurement of time and timekeeping. Chronometry enables the establishment of standard measurements of time, which have applications in a broad range of social and scientific areas. ''Horology'' usually refers specifically to the study of mechanical timekeeping devices, while ''chronometry'' is broader in scope, also including biological behaviours with respect to time (biochronometry), as well as the dating of geological material (geochronometry). Horology is commonly used specifically with reference to the mechanical instruments created to keep time: clocks, watches, clockwork, sundials, hourglasses, Water clock, clepsydras, timers, time recorders, marine chronometers, and atomic clocks are all examples of Measuring instrument, instruments used to measure time. People interested in horology are called ''horologists''. That term is used both by people who deal professionally with timekeeping apparatuses, as well as enthus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meridians (geography)
Meridian or a meridian line (from Latin ''meridies'' via Old French ''meridiane'', meaning “midday”) may refer to Science * Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon **Central meridian (astronomy) * Meridian (geography), a longitude line, i.e. a line of constant longitude, or in other words an imaginary arc on the Earth's surface from the North Pole to the South Pole ** Meridian arc, the distance between two points with the same longitude ** Prime meridian, origin of longitudes ** Principal meridian, arbitrary meridians used as references in land surveying * Meridian line, used with a gnomon to Sundial#Meridian lines, measure solar elevation and time of year * Autonomous sensory meridian response, a static-like or tingling sensation on the skin Places Cities and towns * Meridian, California (other), U.S., multiple California towns named Meridian * Meridian, Colorado, U.S. * Meridian Village, Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Admiralty
The Admiralty was a Departments of the Government of the United Kingdom, department of the Government of the United Kingdom that was responsible for the command of the Royal Navy. Historically, its titular head was the Lord High Admiral of the United Kingdom, Lord High Admiral – one of the Great Officers of State. For much of its history, from the early Admiralty in the 18th century, 18th century until its abolition, the role of the Lord High Admiral was almost invariably put "in commission" and exercised by the Lords Commissioner of the Admiralty, who sat on the governing Board of Admiralty, rather than by a single person. The Admiralty was replaced by the Admiralty Board (United Kingdom), Admiralty Board in 1964, as part of the reforms that created the Ministry of Defence (United Kingdom), Ministry of Defence and its Navy Department (Ministry of Defence), Navy Department (later Navy Command (Ministry of Defence), Navy Command). Before the Acts of Union 1707, the Office of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Nautical Almanac
''The Nautical Almanac'' has been the familiar name for a series of official British almanacs published under various titles since the first issue of ''The Nautical Almanac and Astronomical Ephemeris'', for 1767: this was the first nautical almanac to contain data dedicated to the convenient determination of longitude at sea. It was originally published from the Royal Greenwich Observatory in England. 'ESAE 1961': Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris and Nautical Almanac' ('prepared jointly by the Nautical Almanac Offices of the United Kingdom and the United States of America', HMSO, London, 1961)'ESAA 1992': ed. P.K. Seidelmann, Explanatory Supplement to the Astronomical Almanac' (CA, 1992). A detailed account of how the publication was produced in its earliest years has been published by the National Maritime Museum. Since 1958 (with the issue for the year 1960), His Majesty's Nautical Almanac Office and the US Naval Observat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Royal Navy
The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom of England, English and Kingdom of Scotland, Scottish kings from the early Middle Ages, medieval period, the first major maritime engagements were fought in the Hundred Years' War against Kingdom of France, France. The modern Royal Navy traces its origins to the English Navy of the early 16th century; the oldest of the British Armed Forces, UK's armed services, it is consequently known as the Senior Service. From the early 18th century until the World War II, Second World War, it was the world's most powerful navy. The Royal Navy played a key part in establishing and defending the British Empire, and four Imperial fortress colonies and a string of imperial bases and coaling stations secured the Royal Navy's ability to assert naval superior ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of UTC Time Offsets
This is a list of the UTC time offsets, showing the difference in hours and minutes from Coordinated Universal Time (UTC), from the westernmost (−12:00) to the easternmost (+14:00). It includes countries and regions that observe them during standard time or year-round. The main purpose of this page is to list the current standard time offsets of different countries, territories and regions. Information on daylight saving time or historical changes in offsets can be found in the individual offset articles (e.g. UTC+01:00) or the country-specific time articles (e.g. Time in Russia). Places that observe daylight saving time (DST) during their respective summer periods are listed only once, at the offset for their winter (usually known as "standard") period; see their individual articles for more information. A source for detailed DST and historical information is the tz database. Note that there are many instances of unofficial observation of a different offset (and/or DST) than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Territorial Waters
Territorial waters are informally an area of water where a sovereign state has jurisdiction, including internal waters, the territorial sea, the contiguous zone, the exclusive economic zone, and potentially the extended continental shelf (these components are sometimes collectively called the maritime zones). In a narrower sense, the term is often used as a synonym for the territorial sea. Vessels have different rights and duties when passing through each area defined by the United Nations Convention on the Law of the Sea (UNCLOS), one of the most ratified treaties. States cannot exercise their jurisdiction in waters beyond the exclusive economic zone, which are known as the high seas. Baseline Normally, the baseline is the low-water line along the coast as marked on large-scale charts that the coastal state recognizes. This is either the low-water mark closest to the shore or an unlimited distance from permanently exposed land, provided that some portion of elevations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
180th Meridian
The 180th meridian or antimeridian is the meridian (geography), meridian 180° both east and west of the prime meridian in a Geographic coordinate system, geographical coordinate system. The longitude at this line can be given as either east or west. On Earth, the prime and 180th meridians form a great ellipse that divides the planet into the Western Hemisphere, Western and Eastern Hemispheres. Locations The antimeridian passes mostly through the open waters of the Pacific Ocean but also runs across land in Russia, Fiji, and Antarctica. An important function of this meridian is its use as the basis for the International Date Line, which snakes around national borders to maintain date consistency within the territories of Russia, the United States, Kiribati, Fiji and New Zealand. Starting at the North Pole of the Earth and heading south to the South Pole, the 180th meridian passes through: The meridian also passes between (but not particularly close to): *through the Aleu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gore (segment)
A gore is a sector of a curved surface or the curved surface that lies between two close lines of longitude on a globe and may be flattened to a plane surface with little distortion. The term has been extended to include similarly shaped pieces such as the panels of a hot-air balloon or parachute, or the triangular insert that allows extra movement in a garment (see Gore (fabrics)). Examples upleft, Red hot-air balloon, made from gores of material * Globes of the Earth and the celestial sphere were first mass-produced by Johannes Schöner using a process of printing map details on 12 paper gores that were cut out then pasted to a sphere. This process is still often used. The gores are conveniently made to each have a width of 30 degrees of longitude matching the principal meridians from the South Pole and North Pole to the Equator. * Parachutes and hot air balloons are made from gores of lightweight material. The gores are cut from flat material and stitched toget ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
