[2] Cassini data has revealed a loss of acetylene in the white clouds, an increase of phosphine, and an unusual temperature drop in the center of the storm.
[3] After the visible aspects of the storm subsided, in 2012, a "belch" of heat and ethylene was emitted from two hotspots that merged.
During the Voyager 2 flyby in 1981 a similar "storm alley" was observed in the northern hemisphere (33.5°N–38°N) at the position of the 1903 and 2010 GWSs.
[5] Though computer modelling had by the early 1990s suggested these massive atmospheric upwellings were caused by thermal instability,[12] in 2015 two Caltech planetary scientists proposed a more detailed mechanism.
The theory is that storms are significantly delayed from the winter solstice due to the time it takes for the very large atmosphere to cool.
The team proposes that similar storms are not seen on Jupiter because that planet has less water vapor in its upper atmosphere.
The water ice is delivered by powerful convections originating from about 200 km deep in Saturn's atmosphere.
[5] Saturn's rings block the view of the northern hemisphere from Earth during the winter solstice, so historical data on the GWS is unavailable during this season,[15] but the Cassini space probe has been able to observe the whole planet since it arrived shortly after the winter solstice in 2004.