a small, but fairly intense maritime cyclone that forms poleward of the main baroclinic zone (the polar front or other major baroclinic zone)
A small depression, usually without fronts, which forms in polar air at high latitudes, chiefly during the winter. They often bring heavy snowfall.
small, shallow depression which forms mainly in winter over some high-latitude seas within a polar or arctic air mass; its motion is approximately the same as the air stream in which it is embedded.
A small but intense cyclone that forms in cold polar air advected over warmer water. These vortices often form in the subpolar North Pacific and subpolar North Atlantic equatorward of the sea ice margin. Horizontal scales range from several tens to several hundreds of kilometers. Because of strong winds and intense precipitation, these cyclones are sometimes referred to as "arctic hurricanes."
A polar low is a small-scale, short-lived atmospheric low pressure system (depression) that is found over the ocean areas poleward of the main polar front in both the Northern and Southern Hemispheres. The systems usually have a horizontal length scale of less than 1,000 km and exist for less than a couple of days. They are part of the larger class of mesoscale weather systems.