Editing Surface weather analysis (section)

==== Occluded front ====
{{Main|Occluded front}}The classical view of an [[occluded front]] is that they are formed when a cold front overtakes a warm front.<ref>University of Illinois. [http://ww2010.atmos.uiuc.edu/(Gl)/guides/mtr/af/frnts/ofdef.rxml Occluded Front.] Retrieved on 2006-10-22.</ref> A more modern view suggests that they form directly during the wrap-up of the [[Baroclinity|baroclinic zone]] during [[cyclogenesis]], and lengthen due to flow [[Deformation (meteorology)|deformation]] and rotation around the cyclone.<ref>{{Cite journal|last1=Schultz|first1=David M.|last2=Vaughan|first2=Geraint|date=2011-04-01|title=Occluded Fronts and the Occlusion Process: A Fresh Look at Conventional Wisdom|journal=Bulletin of the American Meteorological Society|language=en|volume=92|issue=4|pages=443–466|doi=10.1175/2010BAMS3057.1|bibcode=2011BAMS...92..443S|issn=0003-0007|doi-access=free}}</ref>

Occluded fronts are indicated on a weather map by a purple line with alternating half-circles and triangles pointing in direction of travel: that is, with a mixture of warm and cold frontal colors and symbols. Occlusions can be divided into warm vs. cold types.<ref>{{Cite journal|last1=Stoelinga|first1=Mark T.|last2=Locatelli|first2=John D.|last3=Hobbs|first3=Peter V.|title=Warm Occlusions, Cold Occlusions, and Forward-Tilting Cold Fronts |date=2002-05-01|journal=Bulletin of the American Meteorological Society|language=en|volume=83|issue=5|pages=709–722|doi=10.1175/1520-0477(2002)083<0709:WOCOAF>2.3.CO;2|bibcode=2002BAMS...83..709S |issn=0003-0007|doi-access=free}}</ref> In a cold occlusion, the air mass overtaking the warm front is cooler than the cool air ahead of the warm front, and plows under both air masses. In a warm occlusion, the air mass overtaking the warm front is not as cool as the cold air ahead of the warm front, and rides over the colder air mass while lifting the warm air. Occluded fronts are indicated on a weather map by a purple line with alternating half-circles and triangles pointing in direction of travel.<ref name="DR"/>

Occluded fronts usually form around low pressure systems in the mature or late stages of their life cycle, but some continue to deepen after occlusion, and some do not form occluded fronts at all. The weather associated with an occluded front includes a variety of cloud and precipitation patterns, including dry slots and banded precipitation. Cold, warm and occluded fronts often meet at the point of occlusion or triple point.<ref>National Weather Service Office, Norman, Oklahoma. [http://www.srh.noaa.gov/oun/severewx/glossary4.php#t Triple Point.] Retrieved on 2006-10-22. {{webarchive|url=https://web.archive.org/web/20061009165650/http://www.srh.noaa.gov/oun/severewx/glossary4.php#t|date=October 9, 2006}}</ref> [[Image:NWS weather fronts.svg|thumb|A guide to the symbols for [[weather fronts]] that may be found on a weather map:<br />
1. cold front<br />
2. warm front<br />
3. stationary front<br />
4. occluded front<br />
5. surface trough<br />
6. squall line<br />
7. dry line<br />
8. tropical wave<br />
9. Trowal]]