Editing Mesocyclone (section)

== Description ==
Mesocyclones are medium-scale vortices of rising and converging air that circulate around a vertical axis. They are most often associated with a local [[low-pressure area|region of low-pressure]]. [[Cyclonic rotation|Their rotation]] is (usually) in the same direction as low pressure systems in a given hemisphere: counter-clockwise in the northern, and clockwise in the southern hemisphere, with the only occasional exceptions being the smallest-scale mesocyclones. Mesoanticyclones that rotate in an opposite direction may accompany mesocyclones within a supercell but these tend to be weaker and often more transient than mesocyclones, which can be sustained for tens of minutes or hours, and also cyclically form in succession within a supercell. Mesoanticyclones are relatively common with left-moving supercells that split from parent supercells in certain vertical wind shear regimes.

A mesocyclone is usually a phenomenon that is difficult to observe directly. Visual evidence of rotation – such as curved [[Inflow (meteorology)#Thunderstorms|inflow bands]] – may suggest the presence of a mesocyclone, but the cylinder of circulating air is often too large to be recognized when viewed from the ground, or may not carry clouds distinct enough from the surrounding calmer air to make the circulating air flow obvious.

Mesocyclones are identified by [[Weather radar#Velocity|Doppler weather radar]] observations as a rotation signature which meets specific criteria for magnitude, vertical depth, and duration. On U.S. [[NEXRAD]] radar displays, algorithmically identified mesocyclones, such as by the [[mesocyclone detection algorithm]] (MDA), are typically highlighted by a yellow solid circle on the [[Doppler effect|Doppler]] velocity display; other weather services may have other conventions.{{cn|date=May 2024}}