Reply #17: It's the angle

[Debo]

The first picture shows the smoke as white or grey because you see the side that the sun is hitting. Look at the shadows on the smoke, sun is shining from the left. It has a light source that makes the smoke look lighter. The other picture is from an angle that puts the sun on the opposite side of the smoke from the photographer so there is no lighting on the smoke which is why it looks black.