Editing Funnel cloud (section)

=="Classic" funnel clouds==
If a funnel cloud touches the surface, the feature is considered a tornado, although ground level circulations begin before the visible condensation cloud appears. Most tornadoes begin as funnel clouds, but some funnel clouds do not make surface contact and these cannot be counted as tornadoes from the perspective of a naked eye observer, even as tornadic circulations of some [[Tornado intensity|intensity]] almost always are detectable when low-level [[Weather radar|radar]] observations are available. Also, tornadoes occur with some frequency without an associated [[condensation]] funnel. The term '''condensation funnel''' may refer to either a tornadic cloud or a funnel cloud aloft, but the term funnel cloud exclusively refers to a rotating condensation funnel not reaching the surface. If strong [[cyclone|cyclonic]] winds are occurring at the surface and are connected to a cloud base, regardless of condensation, then the feature is a tornado.<ref name="FAQ">{{cite web |url = https://www.spc.noaa.gov/faq/tornado/ |title =  What's the difference between a funnel cloud and a tornado? What is a funnel cloud? |last = Edwards |first = Roger |date = 19 April 2018 |website = The Online Tornado FAQ |publisher = NWS Storm Prediction Center |access-date = 2019-12-17 }}</ref>

Funnel clouds result from the low [[air pressure]]s found within tornadoes. The low air pressure causes air flowing towards the vortex to [[Adiabatic process#Adiabatic compression and expansion|expand and cool]]. If the air is sufficiently moist and cools to the [[dew point]], a funnel cloud is produced. The air pressure around the outer edge of the funnel cloud generally corresponds to the [[Lifted condensation level|air pressure]] of the [[cloud base]] of the parent cloud.<ref name="Stull">{{cite book |last1=Stull |first1=Roland |title=Practical Meteorology |date=2017 |publisher=University of British Columbia |isbn=978-0-88865-283-6 |url=https://geo.libretexts.org/Bookshelves/Meteorology_and_Climate_Science/Practical_Meteorology_(Stull)/15%3A_Thunderstorm_Hazards/15.03%3A_Section_4- |via=LibreTexts |access-date=30 January 2024 |chapter=15.4: Tornadoes}}</ref>

Debris swirls are usually evident prior to the condensation funnel reaching the surface. Some tornadoes may appear only as a debris swirl, with no obvious funnel cloud extending below the rotating cloud base at any time during the [[Tornadogenesis|tornadic life cycle]]. The surface level vortex tends to strengthen over time following initial formation, making the debris swirls and the condensation more apparent.<ref>{{Cite journal |last1=Varaksin |first1=Aleksey Yu |last2=Ryzhkov |first2=Sergei V. |date=October 2022 |title=Vortex Flows with Particles and Droplets (A Review) |journal=Symmetry |language=en |volume=14 |issue=10 |pages=2016 |doi=10.3390/sym14102016 |bibcode=2022Symm...14.2016V |issn=2073-8994 |doi-access=free }}</ref>

In cloud nomenclature, any funnel- or inverted-funnel-shaped cloud descending from cumulus or cumulonimbus clouds is technically described as an accessory feature called ''tuba''. The terms ''tuba'' and ''funnel cloud'' are nearly but not exactly synonymous; a [[wall cloud]], for example, is also a form of ''tuba''. Funnel clouds associated with supercells usually form within and under wall clouds.