 Schematic drawing of a simple mercury barometer with vertical mercury column and reservoir at base | | | A barometer is an instrument used to measure atmospheric pressure. It can measure the pressure exerted by the atmosphere by using water, air, or mercury. Pressure tendency can forecast short term changes in the weather. Numerous measurements of air pressure are used within surface weather analysis to help find surface troughs, high pressure systems, and frontal boundaries. Image File history File links This is a lossless scalable vector image. ...
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Atmospheric pressure is the pressure at any given point in the Earths atmosphere. ...
A surface weather analysis for the United States on October 21, 2006. ...
History
The first barometer is thought to have been built unintentionally by Gasparo Berti, sometime between 1640 and 1643.[1] Evangelista Torricelli is generally credited with inventing the barometer. Evangelista Torricelli portrayed on the frontpage of Lezioni dEvangelista Torricelli. ...
Types
Water-based barometers This concept of "decreasing atmospheric pressure predicts stormy weather" was invented by Lucien Vidie and is the basis for a basic weather prediction device called a weather glass or thunder glass. It can also be called a "storm glass" or a "Goethe barometer" (the writer Goethe popularized it in Germany). It consists of a glass container with a sealed body, half filled with water. A narrow spout connects to the body below the water level and rises above the water level, where it is open to the atmosphere. When the air pressure is lower than it was at the time the body was sealed, the water level in the spout will rise above the water level in the body; when the air pressure is higher, the water level in the spout will drop below the water level in the body. A variation of this type of barometer can be easily made at home.[2] Johann Wolfgang von Goethe Johann Wolfgang von Goethe (pronounced [gø tə]) (August 28, 1749–March 22, 1832) was a German writer, politician, humanist, scientist, and philosopher. ...
Mercury barometers A standard mercury barometer has a glass tube of about 30 inches (about 76 cm) in height, closed at one end, with an open mercury-filled reservoir at the base. Mercury in the tube adjusts until the weight of the mercury column balances the atmospheric force exerted on the reservoir. High atmospheric pressure places more force on the reservoir, forcing mercury higher in the column. Low pressure allows the mercury to drop to a lower level in the column by lowering the force placed on the reservoir. Since higher temperature at the instrument will reduce the density of the mercury the scale for reading the height of the mercury is adjusted to compensate for this effect. An inch (plural: inches; symbol or abbreviation: in or, sometimes, ″ - a double prime) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. ...
This article is about the unit of length. ...
Torricelli documented that the height of the mercury in a barometer changed slightly each day and concluded that this was due to the changing pressure in the atmosphere[3]. He wrote: "We live submerged at the bottom of an ocean of elementary air, which is known by incontestable experiments to have weight". Air redirects here. ...
The mercury barometer's design gives rise to the expression of atmospheric pressure in inches or millimeters (torr): the pressure is quoted as the level of the mercury's height in the vertical column. 1 atmosphere is equivalent to about 29.9 inches, or 760 millimeters, of mercury. The use of this unit is still popular in the United States, although it has been disused in favor of SI or metric units in other parts of the world. Barometers of this type normally measure atmospheric pressures between 28 and 31 inches of mercury. Look up si, Si, SI in Wiktionary, the free dictionary. ...
Design changes to make the instrument more sensitive, simpler to read, and easier to transport resulted in variations such as the basin, siphon, wheel, cistern, Fortin, multiple folded, stereometric, and balance barometers. Fitzroy barometers combine the standard mercury barometer with a thermometer, as well as a guide of how to interpret pressure changes. Vice-Admiral Robert FitzRoy (5 July 1805 – 30 April 1865) achieved lasting fame as the captain of HMS Beagle during Charles Darwins famous voyage, and as a pioneering meteorologist who made accurate weather forecasting a reality. ...
On June 5, 2007, a European Union directive was enacted to restrict the sale of mercury, thus effectively ending the production of new mercury barometers in Europe. is the 156th day of the year (157th in leap years) in the Gregorian calendar. ...
Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ...
Image File history File links Download high resolution version (875x708, 280 KB) Licensing I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ...
Image File history File links Download high resolution version (875x708, 280 KB) Licensing I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ...
Aneroid barometers - See also: Barograph
An aneroid barometer uses a small, flexible metal box called an aneroid cell. This aneroid capsule(cell) is made from an alloy of beryllium and copper.[4] The evacuated capsule (or usually more capsules) is prevented from collapsing by a strong spring. Small changes in external air pressure cause the cell to expand or contract. This expansion and contraction drives mechanical levers such that the tiny movements of the capsule are amplified and displayed on the face of the aneroid barometer. Many models include a manually set needle which is used to mark the current measurement so a change can be seen. In addition, the mechanism is made deliberately 'stiff' so that tapping the barometer reveals whether the pressure is rising or falling as the pointer moves.They are used for measuring atmospheric pressure. A barograph is a recording aneroid barometer. ...
Image File history File linksMetadata Download high-resolution version (1600x1200, 597 KB) [edit] Summary [edit] Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Barometer Metadata This file contains additional information, probably added from the digital camera or...
Image File history File linksMetadata Download high-resolution version (1600x1200, 597 KB) [edit] Summary [edit] Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Barometer Metadata This file contains additional information, probably added from the digital camera or...
Barographs A barograph, which records a graph of some atmospheric pressure, uses an aneroid barometer mechanism to move a needle on a smoked foil or to move a pen upon paper, both of which are attached to a drum moved by clockwork.[5] A barograph is a recording aneroid barometer. ...
Barographs may be calibrated for altitude and this type is often used to preserve a record of balloon and glider flights.
Applications - See also: Surface weather analysis
- See also: Weather forecasting
 Barograph using five stacked aneroid barometer cells. A barometer is commonly used for weather prediction, as high air pressure in a region indicates fair weather while low pressure indicates that storms are more likely. When used in combination with wind observations, reasonably accurate short term forecasts can be made.[6] Simultaneous barometric readings from across a network of weather stations allow maps of air pressure to be produced, which were the first form of the modern weather map when created in the 19th century. Isobars, lines of equal pressure, when drawn on such a map, gives a contour map showing areas of high and low pressure. Localized high atmospheric pressure acts as a barrier to approaching weather systems, diverting their course. Low atmospheric pressure, on the other hand, represents the path of least resistance for a weather system, making it more likely that low pressure will be associated with increased storm activities. If the barometer is falling then deteriorating weather or some form of precipitation will fall, however if the barometer is rising then there will be nice weather or no precipitation. A surface weather analysis for the United States on October 21, 2006. ...
Modern weather predictions aid in timely evacuations and potentially save lives and property damage Human beings have attempted to predict the weather since time immemorial. ...
Image File history File links Barograph_01. ...
Image File history File links Barograph_01. ...
A barograph is a recording aneroid barometer. ...
For the geological process, see Weathering or Erosion. ...
Isobar - Wikipedia, the free encyclopedia /**/ @import /skins-1. ...
Hikers choose the easy way to cross hills. ...
For the geological process, see Weathering or Erosion. ...
Compensations
Temperature The density of mercury will change with temperature, so a reading must be adjusted for the temperature of the instrument. For this purpose a mercury thermometer is usually mounted on the instrument. Temperature compensation of an aneroid barometer is accomplished by including a bi-metal element in the mechanical linkages. Aneroid barometers sold for domestic use seldom go to the trouble. A clinical mercury thermometer A thermometer is a device that measures temperature or temperature gradient, using a variety of different principles. ...
Altitude As the air pressure will be decreased at altitudes above sea level (and increased below sea level) the actual reading of the instrument will be dependent upon its location. This pressure is then converted to an equivalent sea-level pressure for purposes of reporting and for adjusting aircraft altimeters (as aircraft may fly between regions of varying normalized atmospheric pressure owing to the presence of weather systems). Aneroid barometers have a mechanical adjustment for altitude that allows the equivalent sea level pressure to be read directly and without further adjustment if the instrument is not moved to a different altitude. Diagram showing the face of a three-pointer sensitive aircraft altimeter displaying altitude in feet. ...
Patents
 Table of Pneumaticks, 1728 Cyclopaedia - US patent 2194624, "Diaphragm pressure gauge having temperature compensating means", granted 1940-03-26, assigned to Bendix Aviat Corp
- U.S. Patent 2,472,735 : C. J. Ulrich : "Barometric instrument"
- U.S. Patent 2,691,305 : H. J. Frank : Barometric altimeter"
- U.S. Patent 3,273,398 : D. C. W. T. Sharp : "Aneroid barometer"
- U.S. Patent 3,397,578 : H. A. Klumb : "Motion amplifying mechanism for pressure responsive instrument movement"
- U.S. Patent 3,643,510 : F. Lissau : "Fluid displacement pressure gauges"
- U.S. Patent 4,106,342 : O. S. Sormunen : "Pressure measuring instrument"
- U.S. Patent 4,238,958 : H. Dostmann : "Barometer"
- U.S. Patent 4,327,583 : T. Fijimoto : "Weather forecasting device"
Image File history File linksMetadata Download high resolution version (1795x2760, 2130 KB) This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain. ...
Image File history File linksMetadata Download high resolution version (1795x2760, 2130 KB) This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain. ...
Year 1940 (MCMXL) was a leap year starting on Monday (link will display the full 1940 calendar) of the Gregorian calendar. ...
March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ...
References Wikimedia Commons has media related to: The Dictionary of Scientific Biography is a reference work consisting of extensive biographies of scientists from antiquity to modern times, excluding scientists who were alive when the Dictionary was first put out. ...
Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ...
is the 125th day of the year (126th in leap years) in the Gregorian calendar. ...
Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ...
is the 125th day of the year (126th in leap years) in the Gregorian calendar. ...
Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ...
is the 125th day of the year (126th in leap years) in the Gregorian calendar. ...
Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ...
is the 125th day of the year (126th in leap years) in the Gregorian calendar. ...
Further reading - Middleton, W.E. Knowles. (1964). The history of the barometer. Baltimore: Johns Hopkins Press. New edition (2002), ISBN 0801871549.
See also ASOS sensors, located at Salinas, CA Automated airport weather stations are automated sensor suites which are designed to serve aviation and meteorological observing needs for safe and efficient aviation operations and weather forecasting. ...
A barograph is a recording aneroid barometer. ...
A surface weather analysis for the United States on October 21, 2006. ...
Modern weather predictions aid in timely evacuations and potentially save lives and property damage Human beings have attempted to predict the weather since time immemorial. ...
A storm glass is a type of barometer, composed of a sealed glass container, filled with liquid, that allows the user to forecast the weather by nothing the apperance of the liquid in the glass. ...
Vice-Admiral Robert FitzRoy (5 July 1805 – 30 April 1865) achieved lasting fame as the captain of HMS Beagle during Charles Darwins famous voyage, and as a pioneering meteorologist who made accurate weather forecasting a reality. ...
External links Look up Barometer in Wiktionary, the free dictionary. | Earth-based meteorological equipment and instrumentation | | | | | Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 151 languages. ...
A hemispherical cup anemometer of the type invented in 2000 by John Thomas Romney Robinson An anemometer is a device for measuring the velocity or the pressure of the wind, and is one instrument used in a weather station. ...
A barograph is a recording aneroid barometer. ...
A ceiling balloon cabinet A fully inflated ceiling balloon Diagram of a filler stand Regulator valve and pressure guages attached to helium cylinder A ceiling balloon is used by meteorologists to determine the height of the base of clouds above ground level during daylight hours. ...
Ceiling projector exterior Interior of a ceiling projector Alidade for use with a ceiling projector The ceiling projector or cloud searchlight is used to measure the height of the base of clouds (called the ceiling) above the ground. ...
Laser Ceilometer A ceilometer is a device that uses a laser or other light source to determine the height of a cloud base. ...
Dark adaptor goggles The Dark adaptor goggles are one of the lesser known tools in the field of meteorology. ...
A disdrometer is an instrument used to measure the drop size distribution and velocity of falling precipitation. ...
Field mill is a specialized instrument used for measuring the strength of electrical fields in the atmosphere near thunderstrom clouds. ...
The interior of a Stevenson screen showing a motorized psychrometer Hygrometers are instruments used for measuring humidity. ...
Standard Ice Accretion Indicator (upside down) The Ice Accretion Indicator is an L-shaped piece of aluminium 38 cm (14. ...
A FASOR used at the Starfire Optical Range for LIDAR and laser guide star experiments is tuned to the sodium D2a line and used to excite sodium atoms in the upper atmosphere. ...
Lightning detector at the Kennedy Space Center in Florida. ...
A nephelometer is an instrument for measuring suspended particulates in a liquid. ...
Nephoscope is instrument for measuring the altitude, direction, and velocity of movement of clouds. ...
Pan evaporation is a measurement that combines or integrates the effects of several climate elements: temperature, humidity, solar radiation, and wind. ...
A pyranometer is a type of actinometer used to measure broadband solar irradiance on a planar surface. ...
radiosonde with measuring instruments A radiosonde (Sonde is German for probe) is a unit for use in weather balloons that measures various atmospheric parameters and transmits them to a fixed receiver. ...
Standard Rain Gauge Tipping Bucket Rain Gauge Recorder Close up of a Tipping Bucket Rain Gauge Recorder chart A rain gauge (also known as an udometer or a pluviometer[fluviograph] or a cup) is a type of instrument used by meteorologists and hydrologists to gather and measure the amount of...
Snow Gauge A snow gauge is a meteorological instrument used to record the depth of snowfall at a specific location. ...
SODAR (sonic detection and ranging) - meteorological instrument which priciple of operation is based on sound waves scattering by atmosheric turbulence. ...
A solarimeter is a pyranometer used to measure combined direct and diffuse solar radiation. ...
A sounding rocket, sometimes called an elevator research rocket, is an instrument-carrying suborbital rocket designed to take measurements and perform scientific experiments during its flight. ...
Exterior of a Stevenson screen Interior of a Stevenson screen A Stevenson screen or Instrument shelter is a meteorological screen to shield instruments against precipitation and direct heat radiation from outside sources, while still allowing air to circulate freely around them. ...
Sunshine Recorders are used to indicate the amount of sunshine at a given location. ...
A thermograph is a recording thermometer. ...
A clinical mercury thermometer A thermometer is a device that measures temperature or temperature gradient, using a variety of different principles. ...
Rawinsonde weather balloon just after launch. ...
Weather radar in Norman, Oklahoma with rainshaft (Source: NOAA) Environment Canada King City (CWKR) weather radar station. ...
Weather vane Weather cock Aerovane A weather vane, also called a wind vane, is a movable device attached to an elevated object such as a roof for showing the direction of the wind. ...
A windsock is a large, conical, open-ended tube designed to indicate wind direction and relative wind speed. ...
A wind profiler is a piece of weather observing equipment that uses sound waves to detect the wind speed and direction at various elevations above the ground. ...
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