Editing Sudden stratospheric warming (section)

== Weather and climate effects ==
Even though SSW events mainly affect the stratosphere, they have a notable influence on surface weather and climate. For example, SSW events often cause normal tropospheric westerly winds to weaken, which can cause temperature drops in mid-latitude regions of the northern hemisphere.<ref>{{cite journal |title=Observed Relationships Between Sudden Stratospheric Warmings and European Climate Extremes |year=2019 |last1=King |first1=A.D. |last2=Butler |first2=A.H. |last3=Jucker |first3=M. |last4=Earl |first4=N.O. |last5=Rudeva |first5=I. |journal=Journal of Geophysical Research: Atmospheres |volume=124 |issue=24 |pages=13943–13961 |doi=10.1029/2019JD030480 |bibcode=2019JGRD..12413943K |doi-access=free |hdl=11343/286789 |hdl-access=free }}</ref> The SSW-induced weakening of the polar vortex allows cold air to sink down from the stratosphere, which can cause widespread cold air outbreaks and intrusions in those areas.<ref>{{Cite journal |last=Kidston |first=Joseph |last2=Scaife |first2=Adam A. |last3=Hardiman |first3=Steven C. |last4=Mitchell |first4=Daniel M. |last5=Butchart |first5=Neal |last6=Baldwin |first6=Mark P. |last7=Gray |first7=Lesley J. |date=2015 |title=Stratospheric influence on tropospheric jet streams, storm tracks and surface weather |url=https://www.nature.com/articles/ngeo2424 |journal=Nature Geoscience |language=en |volume=8 |issue=6 |pages=433–440 |doi=10.1038/ngeo2424 |issn=1752-0908}}</ref> These effects do not occur instantaneously and can take anywhere from 10 days to a week to appear in the troposphere.<ref>{{Cite journal |last=Thompson |first=David W. J. |last2=Wallace |first2=John M. |date=1998 |title=The Arctic oscillation signature in the wintertime geopotential height and temperature fields |url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/98GL00950 |journal=Geophysical Research Letters |language=en |volume=25 |issue=9 |pages=1297–1300 |doi=10.1029/98GL00950 |issn=1944-8007}}</ref>

The resultant cold air intrusions can create blocking patterns and sharper temperature gradients, which can push extratropical cyclone storm tracks closer to the equator. This change often causes more precipitation to be seen in mid-latitude regions, while high-latitude areas often remain dry.<ref>{{Cite journal |last=Reichler |first=Thomas |last2=Kim |first2=Junsu |last3=Manzini |first3=Elisa |last4=Kröger |first4=Jürgen |date=2012 |title=A stratospheric connection to Atlantic climate variability |url=https://www.nature.com/articles/ngeo1586 |journal=Nature Geoscience |language=en |volume=5 |issue=11 |pages=783–787 |doi=10.1038/ngeo1586 |issn=1752-0908}}</ref> The resultant blocking patterns and gradients can also cause an increase in extratropical cyclone intensity, increasing the potential for damaging [[straight-line wind]] events.<ref>{{Cite journal |last=Kidston |first=Joseph |last2=Scaife |first2=Adam A. |last3=Hardiman |first3=Steven C. |last4=Mitchell |first4=Daniel M. |last5=Butchart |first5=Neal |last6=Baldwin |first6=Mark P. |last7=Gray |first7=Lesley J. |date=2015 |title=Stratospheric influence on tropospheric jet streams, storm tracks and surface weather |url=https://www.nature.com/articles/ngeo2424 |journal=Nature Geoscience |language=en |volume=8 |issue=6 |pages=433–440 |doi=10.1038/ngeo2424 |issn=1752-0908}}</ref>