The Copernicus Sentinel-3A satellite in orbit over the Atlantic Ocean close to Spain and Portugal shows where the sky not only features clouds but also crisscross tracks from vessels.
Br />The familiar condensation trails, a.k.a. contrails, seen in the sky usually come from aircraft, so it might seem strange that ships can also occasionally leave their mark in the sky. This rarely seen maritime twist on aircraft contrails was captured by the Sentinel-3A satellite on 16 January 2018. Known as ship tracks, these narrow cloud streaks form when water vapour condenses around
small particles that ships emit in their exhaust fumes. They typically form when low-lying stratus and cumulus clouds are present and when the air surrounding the ship is calm.

Like aircraft contrails, ship tracks may also play a role in our climate by reducing the amount of sunlight that reaches the Earth’s surface or conversely by trapping the Sun’s radiation in the Earth’s atmosphere – but this remains an uncertain aspect of climate science, it is reported.