São Francisco River and Popcorn Clouds Over Northeast Brazil7.4S 38.6W
Popcorn clouds can be seen near the northeastern coastline of Brazil. Water vapor released by plants is more buoyant than dry air, so it rises and eventually condenses into clouds like the popcorn clouds shown in this image.
Visible in the cloudless part of the image is the São Francisco River. With a length of 2,914 kilometres (1,811 mi), it is the longest river that runs entirely in Brazilian territory, and the fourth longest in South America.
The São Francisco originates in the Canastra mountain range in the central-western part of the state of Minas Gerais. It runs generally north in the states of Minas Gerais and Bahia, behind the coastal range, draining an area of over 630,000 square kilometres (240,000 sq mi), before turning east to form the border between Bahia on the right bank and the states of Pernambuco and Alagoas on the left one. After that, it forms the boundary between the states of Alagoas and Sergipe and washes into the Atlantic Ocean (the mouth can be observed south of the image center).