A barometer is a scientific instrument used to measure air pressure. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis to help find surface troughs, high pressure systems and frontal boundaries.

Barometers and pressure altimeters (the most basic and common type of altimeter) are essentially the same instrument, but used for different purposes. An altimeter is intended to be used at different levels matching the corresponding atmospheric pressure to the altitude, while a barometer is kept at the same level and measures subtle pressure changes caused by weather.


The word barometer is derived from the Ancient Greek: βάρος, lit. 'weight', and -meter from Ancient Greek: μέτρον ("measure").


Although Evangelista Torricelli is universally credited with inventing the barometer in 1643,[1][2][3] historical documentation also suggests Gasparo Berti, an Italian mathematician and astronomer, unintentionally built a water barometer sometime between 1640 and 1643.[1][4] French scientist and philosopher René Descartes described the design of an experiment to determine atmospheric pressure as early as 1631, but there is no evidence that he built a working barometer at that time.[1]

On July 27, 1630, Giovanni Battista Baliani wrote a letter to Galileo Galilei explaining an experiment he had made in which a siphon, led over a hill about twenty-one meters high, failed to work. Galileo responded with an explanation of the phenomenon: he proposed that it was the power of a vacuum that held the water up, and at a certain height the amount of water simply became too much and the force could not hold any more, like a cord that can support only so much weight.[5][6] This was a restatement of the theory of horror vacui ("nature abhors a vacuum"), which dates to Aristotle, and which Galileo restated as resistenza del vacuo.

Galileo's ideas reached Rome in December 1638 in his Discorsi. Raffaele Magiotti and Gasparo Berti were excited by these ideas, and decided to seek a better way to attempt to produce a vacuum other than with a siphon. Magiotti devised such an experiment, and sometime between 1639 and 1641, Berti (with Magiotti, Athanasius Kircher and Niccolò Zucchi present) carried it out.[6]

Four accounts of Berti's experiment exist, but a simple model of his experiment consisted of filling with water a long tube that had both ends plugged, then standing the tube in a basin already full of water. The bottom end of the tube was opened, and water that had been inside of it poured out into the basin. However, only part of the water in the tube flowed out, and the level of the water inside the tube stayed at an exact level, which happened to be 10.3 m (34 ft), the same height Baliani and Galileo had observed that was limited by the siphon. What was most important about this experiment was that the lowering water had left a space above it in the tube which had no intermediate contact with air to fill it up. This seemed to suggest the possibility of a vacuum existing in the space above the water.[6]

Torricelli, a friend and student of Galileo, interpreted the results of the experiments in a novel way. He proposed that the weight of the atmosphere, not an attracting force of the vacuum, held the water in the tube. In a letter to Michelangelo Ricci in 1644 concerning the experiments, he wrote:

Many have said that a vacuum does not exist, others that it does exist in spite of the repugnance of nature and with difficulty; I know of no one who has said that it exists without difficulty and without a resistance from nature. I argued thus: If there can be found a manifest cause from which the resistance can be derived which is felt if we try to make a vacuum, it seems to me foolish to try to attribute to vacuum those operations which follow evidently from some other cause; and so by making some very easy calculations, I found that the cause assigned by me (that is, the weight of the atmosphere) ought by itself alone to offer a greater resistance than it does when we try to produce a vacuum.[7]

It was traditionally thought (especially by the Aristotelians) that the air did not have weight: that is, that the kilometers of air above the surface did not exert any weight on the bodies below it. Even Galileo had accepted the weightlessness of air as a simple truth. Torricelli questioned that assumption, and instead proposed that air had weight and that it was the latter (not the attracting force of the vacuum) which held (or rather, pushed) up the column of water. He thought that the level the water stayed at (c. 10.3 m) was reflective of the force of the air's weight pushing on it (specifically, pushing on the water in the basin and thus limiting how much water can fall from the tube into it). In other words, he viewed the barometer as a balance, an instrument for measurement (as opposed to merely being an instrument to create a vacuum), and because he was the first to view it this way, he is traditionally considered the inventor of the barometer (in the sense in which we now use the term).[6]

Because of rumors circulating in Torricelli's gossipy Italian neighborhood, which included that he was engaged in some form of sorcery or witchcraft, Torricelli realized he had to keep his experiment secret to avoid the risk of being arrested. He needed to use a liquid that was heavier than water, and from his previous association and suggestions by Galileo, he deduced by using mercury, a shorter tube could be used. With mercury, which is about 14 times denser than water, a tube only 80 cm was now needed, not 10.5 m.[8]

In 1646, Blaise Pascal along with Pierre Petit, had repeated and perfected Torricelli's experiment after hearing about it from Marin Mersenne, who himself had been shown the experiment by Torricelli toward the end of 1644. Pascal further devised an experiment to test the Aristotelian proposition that it was vapors from the liquid that filled the space in a barometer. His experiment compared water with wine, and since the latter was considered more "spiritous", the Aristotelians expected the wine to stand lower (since more vapors would mean more pushing down on the liquid column). Pascal performed the experiment publicly, inviting the Aristotelians to predict the outcome beforehand. The Aristotelians predicted the wine would stand lower. It did not.[6]

However, Pascal went even further to test the mechanical theory. If, as suspected by mechanical philosophers like Torricelli and Pascal, air had weight, the pressure would be less at higher altitudes. Therefore, Pascal wrote to his brother-in-law, Florin Perier, who lived near a mountain called the Puy de Dome, asking him to perform a crucial experiment. Perier was to take a barometer up the Puy de Dome and make measurements along the way of the height of the column of mercury. He was then to compare it to measurements taken at the foot of the mountain to see if those measurements taken higher up were in fact smaller. In September 1648, Perier carefully and meticulously carried out the experiment, and found that Pascal's predictions had been correct. The mercury barometer stood lower the higher one went.[6]


Water-based barometers

Barometer Goethe 01
Goethe's device

The concept that decreasing atmospheric pressure predicts stormy weather, postulated by Lucien Vidi, provides the theoretical basis for a weather prediction device called a "weather glass" or a "Goethe barometer" (named for Johann Wolfgang Von Goethe, the renowned German writer and polymath who developed a simple but effective weather ball barometer using the principles developed by Torricelli). The French name, le baromètre Liègeois, is used by some English speakers.[9] This name reflects the origins of many early weather glasses – the glass blowers of Liège, Belgium.[9][10]

The weather ball barometer 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. The narrow spout 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.[11]

Mercury barometers

A mercury barometer has a vertical glass tube closed at the top sitting in an open mercury-filled basin at the bottom The weight of the mercury creates a vacuum at the top of the tube known as Torricellian vacuum. 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 levels around 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. The tube has to be at least as long as the amount dipping in the mercury + head space + the maximum length of the column.

Schematic drawing of a simple mercury barometer with vertical mercury column and reservoir at base

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.[1] He wrote: "We live submerged at the bottom of an ocean of elementary air, which is known by incontestable experiments to have weight".[12] Inspired by Torricelli, Otto von Guericke on 5 December 1660 found that air pressure was unusually low and predicted a storm, which occurred the next day.[13]

Baro 3
Fortin barometer

The mercury barometer's design gives rise to the expression of atmospheric pressure in inches or millimeters of mercury (mmHg). A torr was originally defined as 1 mmHg. The pressure is quoted as the level of the mercury's height in the vertical column. Typically, atmospheric pressure is measured between 26.5 inches (670 mm) and 31.5 inches (800 mm) of Hg. One atmosphere (1 atm) is equivalent to 29.92 inches (760 mm) of mercury.

Baro 2
Reservoir of a Fortin barometer

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. Fortin barometers use a variable displacement mercury cistern, usually constructed with a thumbscrew pressing on a leather diaphragm bottom (V in the diagram). This compensates for displacement of mercury in the column with varying pressure. To use a Fortin barometer, the level of mercury is set to zero by using the thumbscrew to make an ivory pointer (O in the diagram) just touch the surface of the mercury. The pressure is then read on the column by adjusting the vernier scale so that the mercury just touches the sightline at Z.. Some models also employ a valve for closing the cistern, enabling the mercury column to be forced to the top of the column for transport. This prevents water-hammer damage to the column in transit.

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.[14]

Vacuum pump oil barometer

Using vacuum pump oil the working fluid in a barometer has led to the creation of the new "World's Tallest Barometer" in February 2013. The barometer at Portland State University (PSU) uses doubly distilled vacuum pump oil and has a nominal height of about 12.4 m for the oil column height; expected excursions are in the range of ±0.4 m over the course of a year. Vacuum pump oil has very low vapor pressure and it is available in a range of densities; the lowest density vacuum oil was chosen for the PSU barometer to maximize the oil column height.[15]

Aneroid barometers

Aneroid barometer
Old aneroid barometer
Modern Aneroid Barometer
Modern aneroid barometer

An aneroid barometer is an instrument used for measuring pressure as a method that does not involve liquid. Invented in 1844 by French scientist Lucien Vidi,[16] the aneroid barometer uses a small, flexible metal box called an aneroid cell (capsule), which is made from an alloy of beryllium and copper. The evacuated capsule (or usually several capsules, stacked to add up their movements) 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. This type of barometer is common in homes and in recreational boats. It is also used in meteorology, mostly in barographs and as a pressure instrument in radiosondes.


A barograph records a graph of atmospheric pressure.

MEMS Barometers

Micro Electro Mechanical Systems (or MEMS) barometers are extremely small devices between 1 and 100 micrometres in size (0.001 to 0.1 mm). They are created via photolithography or photochemical machining. Typical applications include miniaturized weather stations, electronic barometers and altimeters.[17]

A barometer can also be found in smartphones such as the Samsung Galaxy Nexus,[18] Samsung Galaxy S3-S6, Motorola Xoom, Apple iPhone 6 smartphones, and Timex Expedition WS4 smartwatch, based on MEMS and piezoresistive pressure-sensing technologies.[19][20] Inclusion of barometers on smartphones was originally intended to provide a faster GPS lock.[21] However, third party researchers were unable to confirm additional GPS accuracy or lock speed due to barometric readings. The researchers suggest that the inclusion of barometers in smartphones may provide a solution to determining a user's elevation, but also suggest that several pitfalls must first be overcome.[22]

More unusual barometers

Timex Expedition WS4 Barometric chart peaks cloudy close up
Timex Expedition WS4 in Barometric chart mode with weather forecast function.

There are many other more unusual types of barometer. From variations on the storm barometer, such as the Collins Patent Table Barometer, to more traditional-looking designs such as Hooke's Otheometer and the Ross Sympiesometer. Some, such as the Shark Oil barometer,[23] work only in a certain temperature range, achieved in warmer climates.

Galaxy Nexus smartphone
The Galaxy Nexus has a built-in barometer[24]


Barograph dbx1 iso
Digital graphing barometer.
Barograph 01
Analogue recording Barograph using five stacked aneroid barometer cells.

Barometric pressure and the pressure tendency (the change of pressure over time) have been used in weather forecasting since the late 19th century.[25] When used in combination with wind observations, reasonably accurate short-term forecasts can be made.[26] 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, give a contour map showing areas of high and low pressure.[27] Localized high atmospheric pressure acts as a barrier to approaching weather systems, diverting their course. Atmospheric lift caused by low-level wind convergence into the surface brings clouds and sometimes precipitation.[28] The larger the change in pressure, especially if more than 3.5 hPa (0.1 inHg), the greater the change in weather that can be expected. If the pressure drop is rapid, a low pressure system is approaching, and there is a greater chance of rain. Rapid pressure rises, such as in the wake of a cold front, are associated with improving weather conditions, such as clearing skies.[29]

With falling air pressure, gases trapped within the coal in deep mines can escape more freely. Thus low pressure increases the risk of firedamp accumulating. Collieries therefore keep track of the pressure. In the case of the Trimdon Grange colliery disaster of 1882 the mines inspector drew attention to the records and in the report stated "the conditions of atmosphere and temperature may be taken to have reached a dangerous point".[30]

Aneroid barometers are used in scuba diving. A submersible pressure gauge is used to keep track of the contents of the diver's air tank. Another gauge is used to measure the hydrostatic pressure, usually expressed as a depth of sea water. Either or both gauges may be replaced with electronic variants or a dive computer.[31]



The density of mercury will change with increase or decrease in 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 typically have no compensation under the assumption that they will be used within a controlled room temperature range.


NWS Key West office barometer as Hurricane Irma approached
A digital barometer with altimeter setting (for correction) displayed

As the air pressure decreases at altitudes above sea level (and increases below sea level) the uncorrected reading of the barometer will depend on its location. The reading is then adjusted to an equivalent sea-level pressure for purposes of reporting. For example, if a barometer located at sea level and under fair weather conditions is moved to an altitude of 1,000 feet (305 m), about 1 inch of mercury (~35 hPa) must be added on to the reading. The barometer readings at the two locations should be the same if there are negligible changes in time, horizontal distance, and temperature. If this were not done, there would be a false indication of an approaching storm at the higher elevation.

Aneroid barometers have a mechanical adjustment 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. Setting an aneroid barometer is similar to resetting an analog clock that is not at the correct time. Its dial is rotated so that the current atmospheric pressure from a known accurate and nearby barometer (such as the local weather station) is displayed. No calculation is needed, as the source barometer reading has already been converted to equivalent sea-level pressure, and this is transferred to the barometer being set—regardless of its altitude. Though somewhat rare, a few aneroid barometers intended for monitoring the weather are calibrated to manually adjust for altitude. In this case, knowing either the altitude or the current atmospheric pressure would be sufficient for future accurate readings.

The table below shows examples for three locations in the city of San Francisco, California. Note the corrected barometer readings are identical, and based on equivalent sea-level pressure. (Assume a temperature of 15 °C.)

Location Altitude
Uncorrected Patm
(inches Hg)
Corrected Patm
(inches Hg)
Uncorrected Patm
Corrected Patm
City Marina Sea Level (0) 29.92 29.92 0 m 1013 hPa 1013 hPa
Nob Hill 348 29.55 29.92 106 m 1001 hPa 1013 hPa
Mt. Davidson 928 28.94 29.92 283 m 980 hPa 1013 hPa

In 1787, during a scientific expedition on Mont Blanc, De Saussure undertook research and executed physical experiments on the boiling point of water at different heights. He calculated the height at each of his experiments by measuring how long it took an alcohol burner to boil an amount of water, and by these means he determined the height of the mountain to be 4775 metres. (This later turned out to be 32 metres less than the actual height of 4807 metres). For these experiments De Saussure brought specific scientific equipment, such as a barometer and thermometer. His calculated boiling temperature of water at the top of the mountain was fairly accurate, only off by 0.1 Kelvin. [32] [33]

Based on his findings, the altimeter could be developed as a specific application of the barometer. In the mid-19th century, this method was used by explorers.[34]


When atmospheric pressure is measured by a barometer, the pressure is also referred to as the "barometric pressure". Assume a barometer with a cross-sectional area A, a height h, filled with mercury from the bottom at Point B to the top at Point C. The pressure at the bottom of the barometer, Point B, is equal to the atmospheric pressure. The pressure at the very top, Point C, can be taken as zero because there is only mercury vapor above this point and its pressure is very low relative to the atmospheric pressure. Therefore, one can find the atmospheric pressure using the barometer and this equation:[35]

Patm = ρgh

where ρ is the density of mercury, g is the gravitational acceleration, and h is the height of the mercury column above the free surface area. The physical dimensions (length of tube and cross-sectional area of the tube) of the barometer itself have no effect on the height of the fluid column in the tube.

In thermodynamic calculations, a commonly used pressure unit is the "standard atmosphere". This is the pressure resulting from a column of mercury of 760 mm in height at 0 °C. For the density of mercury, use ρHg = 13,595 kg/m3 and for gravitational acceleration use g = 9.807 m/s2.

If water were used (instead of mercury) to meet the standard atmospheric pressure, a water column of roughly 10.3 m (33.8 ft) would be needed.

Standard atmospheric pressure as a function of elevation:

Note: 1 torr = 133.3 Pa = 0.03937 In Hg

Patm Altitude Patm Altitude
101.325 kPa Sea Level (0m) 29.92 In Hg Sea Level (0 ft)
97.71 kPa 305 m 28.86 In Hg 1,000 ft
94.21 kPa 610 m 27.82 In Hg 2,000 ft
89.88 kPa 1,000 m 26.55 In Hg 3,281 ft
84.31 kPa 1,524 m 24.90 In Hg 5,000 ft
79.50 kPa 2,000 m 23.48 In Hg 6,562 ft
69.68 kPa 3,048 m 20.58 In Hg 10,000 ft
54.05 kPa 5,000 m 15.96 In Hg 16,404 ft
46.56 kPa 6,096 m 13.75 In Hg 20,000 ft
37.65 kPa 7,620 m 11.12 In Hg 25,000 ft
32.77 kPa 8,848 m* 9.68 In Hg 29,029 ft*
26.44 kPa 10,000 m 7.81 In Hg 32,808 ft
11.65 kPa 15,240 m 3.44 In Hg 50,000 ft
5.53 kPa 20,000 m 1.63 In Hg 65,617 ft


Table of Pneumaticks, Cyclopaedia, Volume 2
Table of Pneumaticks, 1728 Cyclopaedia

See also


  1. ^ a b c d "The Invention of the Barometer". Retrieved 2010-02-04.
  2. ^ "History of the Barometer". Archived from the original on 2009-09-25. Retrieved 2010-02-04.
  3. ^ "Evangelista Torricelli, The Invention of the Barometer". Archived from the original on 9 February 2010. Retrieved 2010-02-04.
  4. ^ Drake, Stillman (1970). "Berti, Gasparo". Dictionary of Scientific Biography. 2. New York: Charles Scribner's Sons. pp. 83–84. ISBN 978-0-684-10114-9.
  5. ^ Shea, William R. (2003). Designing Experiments & Games of Chance: The Unconventional Science of Blaise Pascal. Science History Publications. pp. 21–. ISBN 978-0-88135-376-1. Retrieved 10 October 2012.
  6. ^ a b c d e f "History of the Barometer". 2002-01-21. Archived from the original on 6 January 2010. Retrieved 2010-02-04.
  7. ^ "Torricelli's letter to Michelangelo Ricci". Retrieved 2010-02-04.
  8. ^ "Brief History of the Barometer". Archived from the original on 14 January 2010. Retrieved 2010-02-04.
  9. ^ a b Gerard L'E. Turner, Nineteenth Century Scientific Instruments, Sotheby Publications, 1983, p 236, ISBN 0-85667-170-3
  10. ^ Claus Zittle, Philosophies of Technology: Francis Bacon and His Contemporaries, BRILL 2008, pp 115, 116 ISBN 90-04-17050-2
  11. ^ Jet Stream. Learning Lesson: Measure the Pressure – The "Wet" Barometer. Retrieved on 2019-01-21.
  12. ^ Strangeways, Ian. Measuring the Natural Environment. Cambridge University Press, 2000, p. 92.
  13. ^ Ley, Willy (June 1966). "The Re-Designed Solar System". For Your Information. Galaxy Science Fiction. pp. 94–106.
  14. ^ Jones H. (10 July 2007). "EU bans mercury in barometers, thermometers". Reuters. Retrieved 12 September 2017.
  15. ^ Tomlinson, Stuart (February 10, 2013) Large barometer at Portland State University could be the tallest in the world.
  16. ^ Figuier, Louis; Gautier, Émile (1867). L'Année scientifique et industrielle. L. Hachette et cie. pp. 485–486.
  17. ^ "MEMS Barometric Pressure Sensor". Sensors & Transducers E-Digest. 92 (4). 2008. Retrieved 13 June 2014.
  18. ^ This Is the Samsung Galaxy Nexus, Google's New Official Android Phone. (2011-10-18). Retrieved on 2011-11-15.
  19. ^ Molen, Brad (2011-10-20). "Behind the glass: a detailed tour inside the Samsung Galaxy Nexus". Engadget. Engadget. Archived from the original on 2014-12-05. Retrieved 2015-06-23. Barometric pressure sensor: BOSCH BMP180
  20. ^ "BMP180: Digital, barometric pressure sensor" (PDF). Bosch. Archived from the original (PDF) on 2015-06-23. Retrieved 2015-06-23.
  21. ^ Galaxy Nexus barometer explained, Sam Champion not out of a job. Engadget (2011-10-20). Retrieved on 2011-12-03.
  22. ^ Muralidharan, Kartik; Khan, Azeem Javed; Misra, Archan; Balan, Rajesh Krishna; Agarwal, Sharad (2014-02-26). "Barometric Phone Sensors – More Hype Than Hope!". ACM HotMobile: 2. Retrieved 2015-06-23.
  23. ^ Shark Oil Barometer Archived July 20, 2011, at the Wayback Machine Barometer World.
  24. ^ Galaxy Nexus. Retrieved on 2011-12-03.
  25. ^ Understanding air pressure. USA Today.
  26. ^ Using winds and a barometer to make forecasts. USA Today (17 May 2005).
  27. ^ Hopkins, Edward J. (1996-06-10). "Surface Weather Analysis Chart". University of Wisconsin. Archived from the original on 28 April 2007. Retrieved 2007-05-10.
  28. ^ Pearce, Robert Penrose (2002). Meteorology at the Millennium. Academic Press. p. 66. ISBN 978-0-12-548035-2. Retrieved 2009-01-02.
  29. ^ Applying The Barometer To Weather Watching. Weather Doctor.
  30. ^ Report on the Explosion which occurred at the Trimdon Grange Colliery on the 16th February 1882, retrieved 23 July 2015
  31. ^ The Encyclopedia of Recreational Diving. Santa Ana, CA, USA: Professional Association of Diving Instructors. 1990. pp. 3–96–3–99. ISBN 978-1-878663-02-3.
  32. ^ Article on the climb of the Mont Blanc by Horace-Bénédict de Saussure
  33. ^ L. Touret, 'In het spoor van Horace Benedicte de Saussure', in: Teylers Magazijn 4, 1984, p. 1-5 (in Dutch)
  34. ^ Berberan-Santos, M. N.; Bodunov, E. N.; Pogliani, L. (1997). "On the barometric formula". American Journal of Physics. 65 (5): 404–412. Bibcode:1997AmJPh..65..404B. doi:10.1119/1.18555.
  35. ^ Cengal, Yunus A. and Boles, Michael A. (2014) Thermodynamics: An Engineering Approach. McGraw-Hill Education. ISBN 978-0073398174

Further reading

  • Wikisource "Barometer" . Encyclopædia Britannica. 3 (11th ed.). 1911.
  • Burch, David F. The Barometer Handbook; a modern look at barometers and applications of barometric pressure. Seattle: Starpath Publications (2009), ISBN 978-0-914025-12-2.
  • Middleton, W. E. Knowles. (1964). The history of the barometer. Baltimore: Johns Hopkins Press. New edition (2002), ISBN 0-8018-7154-9.

External links

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The 20-yard shuttle, also simply called the short shuttle, is a test performed by American football athletes at the NFL combine. It is primarily run to evaluate the quickness and change-of-direction ability of players by scouts, particularly for the NFL Draft but also for collegiate recruiting. Although not as highly regarded a test as the 40-yard dash, it is still an important barometer used by NFL personnel to compare players. Canadian football also uses the shuttle test.


A barograph is a barometer that records the barometric pressure over time in graphical form.

Barometer Soup

Barometer Soup is the nineteenth studio album by American popular music singer-songwriter Jimmy Buffett. Released in August 1995, one year after Fruitcakes in May 1994, this album represented a return to his one-album-per-year writing and recording pace of the 1970s and 1980s.

BoxOffice (magazine)

BoxOffice is a film industry magazine dedicated to the movie theatre business published by BoxOffice Media LP. It started in 1920 as The Reel Journal, taking its current name in 1931 and still publishes today, with an intended audience of theatre owners and film professionals.

BoxOffice is the official publication of the National Association of Theatre Owners, a role it took on in 2006. In 1937 the magazine began to publish box office reports; it ended its publication of movie reviews in 2012.The magazine was originally published every Saturday by Associated Publications. Box office performance was expressed as a percentage of normal performance with normal being expressed as 100%. A Barometer issue was published in January with a review of the year including the performance of movies for the year.

Bunny chow

Bunny chow, often referred to simply as a bunny, is a South African fast food dish consisting of a hollowed-out loaf of white bread filled with curry. It ultimately originated among Indian South Africans of Durban. A small version of the bunny chow that uses only a quarter loaf of bread is sometimes called, by black South Africans, a scambane or kota ("quarter"); it is a name that it shares with spatlo, a South African dish that evolved from the bunny chow.The meal is still called "Bunny chow" or "bunnychow" in Afrikaans, being a loanword from English.

Corruption in Denmark

According to the 2018 Corruption Perceptions Index from Transparency International, Denmark ranks first place out of 180 countries and it has consistently been in the top-4 since the publication of the first report in 1995.Moreover, Transparency International's Global Corruption Barometer 2013 shows that the public does not consider corruption a major problem in Danish society, and bribes paid to access public benefits and services are virtually non-existent.The business environment regarding the ethical behaviour of companies' interaction with public officials, politicians and other enterprises, as well as the financial auditing and reporting standards among companies, are very strong, according to the Global Competitiveness Report 2013–2014.The OECD has pointed out in 2013, though, that it had "serious concerns about the lack of enforcement" of bribery paid by Danish companies abroad.

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Evangelista Torricelli

Evangelista Torricelli (Italian: [evandʒeˈlista torriˈtʃɛlli], listen ; 15 October 1608 – 25 October 1647) was an Italian physicist and mathematician, best known for his invention of the barometer, but is also known for his advances in optics and work on the method of indivisibles.

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Pressure Drop (song)

"Pressure Drop" is a song recorded in 1969 by the Maytals for producer Leslie Kong. The song appears on their 1970 album Monkey Man (released in Jamaica by Beverley's Records) and From the Roots (released in the UK by Trojan Records). "Pressure Drop" helped launch the band's career outside Jamaica when the song was featured in the soundtrack to the 1972 film The Harder They Come, which introduced reggae to much of the world. In 2004, Rolling Stone rated the song No. 453 in its list of the 500 Greatest Songs of All Time.

This song has been covered often, most notably by the Specials, Keith Richards, Izzy Stradlin and the Ju Ju Hounds, and the Clash.

"Pressure Drop" refers to the barometric pressure. This song predates modern weather forecasting, and at that time in the context of this song, island populations relied on the simple but reliable instrument (barometer) to predict adverse weather. The liquid barometer displays pressure as a measure of the fluid in a glass tube, and when the air pressure drops the fluid level "drops" accordingly. A rapid drop in air pressure indicates the severity of the approaching storm (hurricane), and is sometimes referred to as "the bottom dropping out". Attention to pressure changes could spell the difference between life and death for an island dweller. "Pressure drop" is used as a clever poetic device in this song, and is the artists way of saying *a storm is coming for you*.The song was featured in the 2004 video game Grand Theft Auto: San Andreas on the radio station K-Jah West.In an interview in 2016, songwriter Frederick "Toots" Hibbert said that "Pressure Drop" was a song about karmic justice.

It’s a song about revenge, but in the form of karma: if you do bad things to innocent people, then bad things will happen to you. The title was a phrase I used to say. If someone done me wrong, rather than fight them like a warrior, I’d say: “The pressure’s going to drop on you.”.

Renewable energy in the Czech Republic

Renewable energy in the Czech Republic describes the renewable energy related development in the Energy in the Czech Republic.

According to Eurostat, renewables share in the Czech Republic in 2009 was 5% of the energy mix in total (Mtoe) and 6% of gross electricity generation (TWh). The energy consumption by fuel included in 2009: 40% coal, petroleum 21%, gas 15%, nuclear 16% and renewables 5%. Most electricity was produced with coal (55%) and nuclear (33%).

Solar power in Belgium

Solar power in Belgium reached an installed capacity of 3,846 MW of power generating 3,149 GWh of electricity in 2017. In 2015 PV solar power accounted for around 4% of Belgium's total electricity demand, the 4th highest penetration figure in the world, although the country is some way behind the leaders Germany, Italy and Greece at between 7% and 8% of electricity demand.Installed capacity grew at an outstanding pace from 2008 until 2012, but its growth has since slowed to a steady pace. Almost all of solar power in Belgium is grid connected.

Solar power in Poland

Solar energy in Poland is a new sector of renewable energy and consists of solar thermal and solar electricity. Solar thermal, used for heating water was widely used in about 1,700,000 square metres (18,000,000 sq ft) of solar thermal collector at the end of 2014. This corresponds to about 1,200 MWth capacity. Solar collectors are the second, after the biomass heating plants, source of "green heat" in Poland. In 2014, Poland was ranked fourth in sales of solar collector installations among European countries.The total solar photovoltaics (PV) power plants connected to the grid in Poland at the end of 2012 were about 1.29 MWp of capacity. According to Energy Regulatory Office photovoltaic power in Poland had 91.82 MWp installed capacity at the end of June 2016.

Solar power in the Czech Republic

The Czech Republic had almost two gigawatts (GW) of photovoltaic capacity at the end of 2010, but installed less than 10 megawatts (MW) in 2011 due to the feed-in tariff being reduced by 25%, after installing almost 1,500 MW the year before. Installations increased to 109 MW in 2012. In 2014, no new installations were reported.

In 2003 a Czech-Austrian information and training center for solar power was founded in the village of Věžovatá Pláně in South Bohemia. That same year major Josef Mach claimed that the electricity from the Temelín nuclear power plant in the Czech Republic would be abandoned. He is known as one of the biggest Temelín opponents in the Czech Republic.

Tempest prognosticator

The tempest prognosticator, also known as the leech barometer, is a 19th-century invention by George Merryweather in which leeches are used in a barometer. The twelve leeches are kept in small bottles inside the device; when they become agitated by an approaching storm they attempt to climb out of the bottles and trigger a small hammer which strikes a bell. The likelihood of a storm is indicated by the number of times the bell is struck.

The Daily Barometer

The Daily Barometer is an independent campus newspaper of Oregon State University, in Corvallis, Oregon. It is published weekly during the fall, winter, and spring quarters, and monthly during the summer.

Also known as The Baro, the news team covers local news and events and brings awareness to important student issues. Students serve as editors, reporters, and photographers to cover news through the newspaper, website, social media, and daily online videos.

Three-cone drill

The three-cone drill, or 3-cone drill, is a test performed by American football athletes at the NFL combine. It is primarily run to evaluate the agility, quickness and fluidity of movement of players by scouts, particularly for the NFL draft but also for collegiate recruiting. While not as highly regarded a test as the 40-yard dash, it is still an important barometer used by NFL personnel to compare players.


The torr (symbol: Torr) is a unit of pressure based on an absolute scale, now defined as exactly 1/760 of a standard atmosphere (101325 Pa). Thus one torr is exactly 101325/760 pascals (≈ 133.32 Pa).

Historically, one torr was intended to be the same as one "millimeter of mercury". However, subsequent redefinitions of the two units made them slightly different (by less than 0.000015%). The torr is not part of the International System of Units (SI), but it is often combined with the metric prefix milli to name one millitorr (mTorr) or 0.001 Torr.

The unit was named after Evangelista Torricelli, an Italian physicist and mathematician who discovered the principle of the barometer in 1644.

Acoustic, sound, vibration
Automotive, transportation
Electric, magnetic, radio
Environment, weather,
Flow, fluid velocity
Ionising radiation,
subatomic particles
Navigation instruments
Position, angle,
Optical, light, imaging
Force, density, level
Thermal, heat,
Proximity, presence
Sensor technology

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