Complex sentence: Polar lows can have a wide range of cloud signatures in satellite imagery, but two broad categories of cloud form have been identified-a spiraliform signature consisting of a number of cloud bands wrapped around the centre of the low.
Split into simpler sentences: 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.