Polar low Polar low over the Barents Sea on February 27 , 1987 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 . Polar lows can be difficult to detect using conventional weather reports and are a hazard to high-latitude operations , such as shipping and gas and oil platforms . Polar lows have been referred to by many other terms , such as comma cloud , mesocyclone , polar mesoscale vortex , Arctic hurricane , Arctic low , and cold air depression . Today the term is usually reserved for the more-vigorous systems that have near-surface winds of at least gale force ( 17 m/s ) . Polar lows were first identified on the meteorological satellite imagery that became available in the 1960s , which revealed many small-scale cloud vortices at high latitudes . The most active polar lows are found over certain ice-free maritime areas in or near the Arctic during the winter , such as the Norwegian Sea , Barents Sea , Sea of Japan , and Gulf of Alaska . Polar lows dissipate rapidly when they make landfall . Antarctic systems tend to be weaker than their northern counterparts since the air-sea temperature differences around the continent are generally smaller . However , vigorous polar lows can be found over the Southern Ocean . Polar lows can have a wide range of cloud signatures in satellite imagery , but two broad categories of cloud forms have been identified . The first is the `` spiraliform '' signature consisting of a number of cloud bands wrapped around the centre of the low . Some polar lows have the appearance in satellite imagery of tropical cyclones , with deep thunderstorm clouds surrounding a cloud-free ‘ eye ’ , which has given rise to the use of the term `` Arctic hurricane '' to describe some of the more active lows . These systems are more common deep within the polar air . The second is a `` comma-shaped '' signature that is found more frequently with systems closer to the polar front . Polar lows form for a number of different reasons , and a spectrum of systems is observed on satellite imagery . A number of lows develop on horizontal temperature gradients through baroclinic instability , and these can have the appearance of small frontal depressions . At the other extreme are the polar lows with extensive cumulonimbus clouds , which are often associated with cold pools in the mid- to upper- troposphere . Polar lows are very difficult to forecast and a nowcasting approach is often used , with the systems being advected with the mid-tropospheric flow . Numerical weather prediction models are only just getting the horizontal and vertical resolution to represent these systems . See also Cyclones and Anticyclones of the world Extratropical - Meso-scale - Polar - Polar low - Subtropical - Tropical Further reading Rasmussen , E.A. and Turner , J. ( 2003 ) . Polar Lows : Mesoscale Weather Systems in the Polar Regions , Cambridge University Press , Cambridge , pp 612 . External links European Polar Lows Working Group NSIDC Polar Low Forecasting by MetEd Categories : Types of cyclone In other languages : Deutsch | Español | Français | Nederlands | Suomi 