The mighty Amazon River springs from glacier-fed streams in the Andes Mountains of Peru, then flows more than 4,049 miles (6,516 km) across South America to reach the northeast coast of Brazil. As it tumbles across the continent, it accumulates sediment—bits of rocks, soil, and clay—both from the surrounding landscape and from the many tributaries that flow into the Amazon.
By the time reached the Atlantic Ocean, the waters of the Amazon are muddy-colored and brimming with sediment. It has been calculated that about 1.3 million tons of sediment pours from the mouth of the Amazon River into the Atlantic Ocean every day. On June 17, 2022, the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a true-color image that clearly shows the massive plume of sediment pouring through the Amazon River Delta and into the Atlantic Ocean.
The milk-chocolate hue of the Amazon River and its sediment plume stand out in sharp contrast with the “popcorn” clouds that cover coastal Brazil. These are low-altitude cumulus clouds that are formed when warm, humid air rises from the forest. As the moisture-filled air rises, it also cools resulting in the development of clouds. There are no clouds over the Amazon River because the river (and the air over the river) is cooler than the rainforest, and the lower temperature inhibits cloud formation.