Editing Barometer (section)

== Applications ==
{{see also|Surface weather analysis|Weather forecasting}}
[[File:barograph dbx1 iso.jpg|thumb|left|Digital graphing barometer]]

Barometric pressure and the pressure tendency (the change of pressure over time) have been used in weather forecasting since the late 19th century.<ref>[https://www.usatoday.com/weather/wbarocx.htm Understanding air pressure.] ''[[USA Today]]''.</ref> When used in combination with wind observations, reasonably accurate short-term forecasts can be made.<ref>[https://www.usatoday.com/weather/wfbarrow.htm Using winds and a barometer to make forecasts.] ''USA Today'' (17 May 2005).</ref> 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. [[Isobar (meteorology)|Isobars]], lines of equal pressure, when drawn on such a map, give a contour map showing areas of high and low pressure.<ref>{{cite web|publisher=University of Wisconsin|author=Hopkins, Edward J. |date=1996-06-10|url=http://www.meteor.wisc.edu/~hopkins/aos100/sfc-anl.htm|title=Surface Weather Analysis Chart|access-date=2007-05-10| archive-url= https://web.archive.org/web/20070428121643/http://www.meteor.wisc.edu/~hopkins/aos100/sfc-anl.htm| archive-date= 28 April 2007 | url-status= live}}</ref> 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 (meteorology)|precipitation]].<ref name="convection">{{cite book|author=Pearce, Robert Penrose |year=2002|url=https://books.google.com/books?id=QECy_UBdyrcC&pg=PA66|title=Meteorology at the Millennium|publisher=Academic Press|page=66|isbn=978-0-12-548035-2|access-date=2009-01-02}}</ref> The larger the change in pressure, especially if more than 3.5&nbsp;hPa (0.1 inHg), the greater the change in weather that can be expected. If the pressure drop is rapid, a [[Low pressure area|low pressure system]] is approaching, and there is a greater chance of rain. [[High pressure area|Rapid pressure rises]], such as in the wake of a [[cold front]], are associated with improving weather conditions, such as clearing skies.<ref>[http://www.islandnet.com/~see/weather/eyes/barometer3.htm Applying The Barometer To Weather Watching.] Weather Doctor.</ref>

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|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".<ref>{{citation | url = http://www.dmm.org.uk/reports/3319-01.htm | title = Report on the Explosion which occurred at the Trimdon Grange Colliery on the 16th February 1882 | access-date = 23 July 2015 }}</ref>

Aneroid barometers are used in [[scuba diving]]. A [[Diving regulator#Submersible pressure gauge (SPG)|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.<ref>{{cite book|title=The Encyclopedia of Recreational Diving|date=1990|publisher=[[Professional Association of Diving Instructors]]|location=Santa Ana, CA|isbn=978-1-878663-02-3|pages=[https://archive.org/details/encyclopediaofre00prof/page/3 3-96–3-99]|url-access=registration|url=https://archive.org/details/encyclopediaofre00prof/page/3}}</ref>