If I understand this correctly, this is something called ‘surface hoar frost‘, where saturated water vapors coming up through cracks in sea ice freeze and crystallize with salt on the ice serving as a nucleus for the frozen vaporized water. A dominant source of sea salt aerosol in Antactica, that scientist suspect may be main cause of tropospheric ozone depletion during the polar sunrise. Oh well, whatever, it is first and foremost absolutely beautiful ! :-)
