Annular tropical cyclone

An annular tropical cyclone is a tropical cyclone that features a normal to large, symmetric eye surrounded by a thick and uniform ring of intense convection, often having a relative lack of discrete rainbands, and bearing a symmetric appearance in general.

The annular hurricane was first defined as a subset of tropical cyclones by John Knaff of Colorado State University and James Kossin of the University of Wisconsin–Madison in 2002 by use of infrared satellite imagery, which serves as the visual means of ascertaining annular characteristics within tropical cyclone.

In addition to the primary defining characteristics, the diurnal pulsation of the cirrus cloud canopy associated with outflow is subdued once storms become annular.

The index takes into account the cloud height of the storm, the radii of the eye, and other similar factors, using satellite imagery, and then produces a number, with the maximum value on the scale being 100.

In addition, storms attaining annular characteristics are less prone to weakening as a result of negative environmental factors.

Annular cyclones can maintain their respective peak intensities for extended periods of time unlike their asymmetric counterparts.

In the same timeframe, the North Atlantic basin only exhibited conducive conditions for annular development 0.8 percent of the time.