Editing Nor'west arch (section)

{{Short description|Föhn cloud formation in New Zealand}}
{{Use dmy dates|date=September 2024}}
{{Use New Zealand English|date=September 2024}}

[[File:Nor'west arch2.JPG|thumb|right|250px|The nor'west arch, viewed from [[Christchurch]], appears as a blue belt of clear sky to the west from which high white cloud streams.]]
The '''nor'west arch''' is a band of high white [[lenticular cloud]] that forms on the eastern side of New Zealand's [[South Island]] and which looks like an arch in an otherwise clear blue sky over the [[Southern Alps]]. It is accompanied by a strong hot northwesterly or northerly wind known as a "nor'wester". In [[Canterbury Region|Canterbury]], where it is a well known feature, it is also called the '''Canterbury arch'''. It also occurs in [[Otago]] and [[Marlborough District|Marlborough]] and east of mountain ranges along the east coast of the [[North Island]].<ref name=NIWA_clouds/>

Closer to the Canterbury coast, some distance from the mountains of the Southern Alps, it appears as a clear area of blue above the mountains, with white cloud streaming to the east from it. The phenomenon is similar to the [[Chinook wind|Chinook arch]] seen in the Pacific regions of the United States and Canada.