Editing Weather map (section)

=== Surface weather analysis ===
[[file:Streamlineanalysispacific.gif|thumb|Streamline analysis of the tropical Pacific Ocean]]
{{See also|Surface weather analysis}}

A surface weather analysis is a type of weather map that depicts positions for [[high-pressure area|high]] and [[low-pressure area]]s, as well as various types of [[synoptic scale]] systems such as [[weather fronts|frontal zones]]. Isotherms can be drawn on these maps, which are lines of equal temperature. Isotherms are drawn normally as solid lines at a preferred temperature interval.<ref name="DataAir">{{cite web|author=DataStreme Atmosphere|publisher=American Meteorological Society|url=http://www.ametsoc.org/amsedu/dstreme/learn/sample.act.html |title=Air Temperature Patterns|date=2008-04-28|access-date=2010-02-07 |archive-url = https://web.archive.org/web/20080511124504/http://www.ametsoc.org/amsedu/dstreme/learn/sample.act.html |archive-date = 2008-05-11}}</ref> They show temperature gradients, which can be useful in finding fronts, which are on the warm side of large temperature gradients. By plotting the freezing line, isotherms can be useful in determination of precipitation type. Mesoscale boundaries such as [[tropical cyclone]]s, outflow boundaries and [[squall line]]s also are analyzed on surface weather analyses.

Isobaric analysis is performed on these maps, which involves the construction of lines of equal mean [[sea level pressure]]. The innermost closed lines indicate the positions of relative maxima and minima in the pressure field. The minima are called low-pressure areas while the maxima are called [[high-pressure area]]s. Highs are often shown as H's whereas [[low-pressure area|lows]] are shown as L's. Elongated areas of low pressure, or troughs, are sometimes plotted as thick, brown dashed lines down the trough axis.<ref>{{cite web|publisher=University of Wisconsin|author=Edward J. Hopkins, Ph.D.|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}}</ref> Isobars are commonly used to place surface boundaries from the [[horse latitudes]] poleward, while streamline analyses are used in the tropics.<ref>{{cite web|author=Bureau of Meteorology|url=http://www.bom.gov.au/nmoc/MSL/WeatherMap.shtml#types|title=The Weather Map|publisher=Commonwealth of Australia|year=2010|access-date=2010-02-06}}</ref> A streamline analysis is a series of arrows oriented parallel to wind, showing wind motion within a certain geographic area. "C"s depict cyclonic flow or likely areas of low pressure, while "A"s depict anticyclonic flow or likely positions of high-pressure areas.<ref>{{cite web|author=[[National Weather Service]] Forecast Office [[Honolulu, Hawaii]]|url=http://www.prh.noaa.gov/hnl/graphics/tropsl.tif|title=Pacific Streamline Analysis|publisher=Pacific Region Headquarters|date=2010-02-07|access-date=2010-02-07}}</ref> An area of confluent streamlines shows the location of [[weather front#Stationary front|shearlines]] within the tropics and subtropics.<ref name="DR"/>