Comma
A Comma is an active, mesoscale cloud spiral in the cold air behind frontal cloud bands, often with significant weather.
A Comma is a very prominent cloud feature developing and xisting in cold air. In order to distinguish the Comma from other features in cold air, the Comma cloudiness is defined as a small to meso-scale cloud spiral consisting of white (i.e. cold) cloud cells partly overlaid by cirrus shields. In most cases the strongest convection can be found in the Comma tail. The scale of a Comma lies between 200 and 1000 km, i.e. much smaller than a fully developed depression or a cyclone. Larger Commas can be a sign of a development process called Cold Air Development, where a Comma increases in size and finally gains some frontal characteristics.