Satellite image of Baltic sea#
Image courtesy of USGS., under PD
Ethereal swirls of grease ice appear turquoise against the midnight blue of the northern Baltic Sea in this false-color satellite image taken over the Aland Islands (red) between Finland and Sweden.
The second stage of sea ice formation, grease ice consists of a viscous mix of tiny ice crystals and resembles an oil slick on the oceans surface. Wind and currents constantly shape and reshape grease ice into surreal, ghostly patterns.