File:Islands in the Aegean Sea (MODIS 2022-07-07).jpg

English: On July 4, 2022, the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a true-color image of sunglint shining on the waters around the many Aegean Islands and the large island of Crete.

The stunning scene is the result of the interplay of water, wind, topography, and the effects of sunlight reflecting off the complex surface. Sunglint, the shiny silvery-gray areas, is created from sunlight bouncing back to the satellite’s imaging instrument. It’s much like what happens when you look at a mirror with the Sun almost directly behind you—you get dazzled by the bright reflection of the light off the smooth surface.

Sunglint differs a bit from your eyes and the mirror, however, in part because the surface of the Earth and oceans are not as uniformly slick as the mirror. Sunglint appears bright only over very smooth surfaces, such as wave-free expanses of water. Where the water is rough, such as areas of turbulence in the flow created by islands, light reflects in many directions and little comes directly back to the instrument, so the roughened water surfaces appear dark.

Dry, cool winds from the north, called the Etesian winds, often blow over the Aegean Sea during summer. On the windward side of the islands, those winds pile up the water and disturb the surface. But as those air masses run into the islands and their rocky peaks, a “wind shadow” with much calmer winds (and seas) form on the leeward side of islands (in this case, the south sides). Darker areas amid the bright streaks could be the result of wind or water turbulence, or perhaps breaks in the wind-blocking land topography.