On August 12, 2019, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired a true-color image of shimmering sunglint on the Mediterranean Sea.
The mirror-like sheen seen in this image is an optical effect called sunglint, which is caused when sunlight reflects off the surface of the water directly back at the satellite sensor. Although the “shine” of sunglint washes out many features, it can also reveal details about the water surface that would ordinarily not be seen from space, such as the interaction of the atmosphere and the surface of the sea. Water needs to be smooth in order to create sunglint; where wakes and waves occur, light doesn’t reflect directly back to the sensor, so it appears dark. Roughened water is often caused by winds interacting with the ocean surface. In this case, winds appear to be stirring the surface of the Mediterranean off both coasts of Italy and north of the coast of Libya.