Editing Surface weather analysis (section)

=== Dry line ===
The [[dry line]] is the boundary between dry and moist air masses east of mountain ranges with similar orientation to the [[Rocky Mountains|Rockies]], depicted at the leading edge of the [[dew point]], or moisture, gradient. Near the surface, warm moist air that is denser than warmer, dryer air wedges under the drier air in a manner similar to that of a cold front wedging under warmer air.<ref>Huaqing Cai. [http://www.atmos.ucla.edu/~caihq/pic/fig23.html Dryline cross section.] {{webarchive|url=https://web.archive.org/web/20080120180130/http://www.atmos.ucla.edu/~caihq/pic/fig23.html |date=2008-01-20 }} Retrieved on 2006-12-05.</ref> When the warm moist air wedged under the drier mass heats up, it becomes less dense and rises and sometimes forms thunderstorms.<ref>{{cite web|url=http://www.accd.edu/sac/earthsci/sgirhard/1370.090/chap3.htm|archive-url=https://web.archive.org/web/20070927000112/http://www.accd.edu/sac/earthsci/sgirhard/1370.090/chap3.htm|title=Lecture 3|archive-date=27 September 2007}}</ref> At higher altitudes, the warm moist air is less dense than the cooler, drier air and the boundary slope reverses. In the vicinity of the reversal aloft, severe weather is possible, especially when a triple point is formed with a cold front.{{Citation needed|date=December 2021}}

During daylight hours, drier air from aloft drifts down to the surface, causing an apparent movement of the dryline eastward. At night, the boundary reverts to the west as there is no longer any solar heating to help mix the lower atmosphere.<ref>Lewis D. Grasso. [https://archive.today/20130116214601/http://ams.allenpress.com/perlserv/?request=get-document&doi=10.1175/1520-0493(2000)128%3C2816:ANSODS%3E2.0.CO;2 A Numerical Simulation of Dryline Sensitivity to Soil Moisture.] Retrieved on 2007-05-10.</ref> If enough moisture converges upon the dryline,  it can be the focus of afternoon and evening thunderstorms.<ref>Glossary of Meteorology. [http://amsglossary.allenpress.com/glossary/search?id=lee-trough1 Lee Trough.] {{webarchive|url=https://web.archive.org/web/20110919042152/http://amsglossary.allenpress.com/glossary/search?id=lee-trough1 |date=2011-09-19 }} Retrieved on 2006-10-22.</ref> A dry line is depicted on United States surface analyses as a brown line with scallops, or bumps, facing into the moist sector. Dry lines are one of the few surface fronts where the special shapes along the drawn boundary do not necessarily reflect the boundary's direction of motion.<ref>University of Illinois. [http://ww2010.atmos.uiuc.edu/(Gl)/guides/mtr/af/frnts/dfdef.rxml Dry Line: A Moisture Boundary.] Retrieved on 2006-10-22.</ref>