Editing Surface weather analysis (section)

==== Stationary fronts and shearlines ====
{{Main|Stationary front}}
A stationary front is a non-moving boundary between two different air masses. They tend to remain in the same area for long periods of time, sometimes undulating in waves.<ref>University of Illinois. [http://ww2010.atmos.uiuc.edu/(Gl)/guides/mtr/af/frnts/sfdef.rxml Stationary Front.] Retrieved on 2006-10-22.</ref> Often a less-steep temperature gradient continues behind (on the cool side of) the sharp frontal zone with more widely spaced isotherms. A wide variety of weather can be found along a stationary front, characterized more by its prolonged presence than by a specific type. Stationary fronts may dissipate after several days, but can change into a cold or warm front if conditions aloft change, driving one air mass toward the other. Stationary fronts are marked on weather maps with alternating red half-circles and blue spikes pointing in opposite directions, indicating no significant movement.{{Citation needed|date=December 2021}}

As airmass temperatures equalize, stationary fronts may become smaller in scale, degenerating to a narrow zone where wind direction changes over a short distance, known as a shear line,<ref>Glossary of Meteorology. [http://amsglossary.allenpress.com/glossary/search?p=1&query=shear+line Shear Line.] {{webarchive|url=https://web.archive.org/web/20070314081220/http://amsglossary.allenpress.com/glossary/search?p=1&query=shear+line |date=2007-03-14 }} Retrieved on 2006-10-22.</ref> depicted as a blue line of single alternating dots and dashes.<ref name="DR"/><ref>Aviation Weather. [https://www.aviationweather.ws/093_Transitory_Systems.php] Retrieved on 2021-03-13.</ref>