Like it was placed ‘just so’, the cloud in this shot was timed.
Sky plays just as important a role in composition as the ground does. Indeed I think we must stop thinking of the landscape as split into symbolic areas such as ‘ground’ and ‘sky’, but instead as ‘shapes’ and ‘tones’. To my mind, sky should be indivisible from ground.
The cloud is just hanging there in the ‘perfect’ space. It is a diagonally balancing object to the volcano Papillon in the lower-right side of the frame. In my mind’s-eye, I see nothing else in the picture apart from the cloud and the volcano. Two objects, both unified, and highly related to each other through placement.
This is why I think areas of the sky play just as important a role in composition as objects on the ground do. Sky is not just a space that has to always be in the frame, and nor does it have to occupy 50% of the frame as it seems to for many images. Sky is just space, like any other space in a composition, and if you use it well it can aid in the power of the composition.
The placement of that cloud (and therefore the timing of the shutter firing was critical), but so too was its shape and volume of area. Had it been much bigger than the volcano, then I think it would have dominated. Instead, it is pleasingly proportionally equal to the volcano, and I find my eye is comfortably bouncing back and forth between the two.
The could is also of a pleasing shape. Not all clouds are created equal, which although rather obvious to some of us, still needs to be pointed out.
A cloud is never just a cloud.