Solar reflections can change the appearance of the ocean when viewed from above, revealing a variety of oceanographic phenomena. (Image credit: NASA/ISS)
In this stunning astronaut photograph, a rare 'solar reflection' transforms the surface of the Mediterranean Sea into a swirling silver mirror surrounding a pair of Greek islands – Milos (centre) and Antimilos (left).
Solar reflection occurs when sunlight bounces off a smooth surface of water directly toward an observer who is orbiting the Earth, like a satellite or an astronaut. It's similar to how light reflects off the sea at sunrise or sunset. However, instead of a bright orange band reflected off the waves, it appears as a huge silvery patch that can cover hundreds of square miles. From space, solar reflections appear to move across the ocean as the Earth rotates.
Wind-driven surface currents, deeper ocean currents, rotating gyres and other oceanographic phenomena create the wavy lines and eddies that crisscross the silvery sea surface in the image, according to NASA's Earth Observatory.
Most of these features are not normally visible from space. However, because they scatter some of the sunlight, they become visible during solar reflection.
Solar reflections can cover hundreds of square miles of ocean surface at once.
One of the most striking oceanographic features in the image is a gyre spinning like a giant whirlpool to the east (right) of Milos. Another interesting detail is a long straight line in the lower left corner of the image, which is likely a ship wake, according to Earth Observatory data.
The rarest feature in the image, however, is a set of parallel lines just off the northwest coast (upper left) of Antimilos. These lines, partly obscured by clouds, represent “internal waves” — massive vertical ripples that travel through the water beneath the surface, according to Earth Observatory data.
Unlike surface waves, which are primarily caused by ocean currents or strong winds, internal waves are formed by gravity waves (not to be confused with gravity waves in spacetime) that pass across the boundary of two fluid media when gravity upsets the equilibrium between them. In this case, the waves ripple along the underwater boundary between two layers of water that have been stratified by temperature and salinity and are disturbed by Earth's changing tides, according to a 2021 article in The Conversation.
While solar reflections are visually impressive, they can be difficult to
Sourse: www.livescience.com
