This reminded me of some of the Superbowl magazine layouts presented in class today, in which the designers used a cutout of Seattle's skyline. This is an effective visual effect because it immediately draws attention, and for this one in particular, the bold colors really make the design pop.
Canada based photographer Matt Molloy is a fan of time lapse portraits and natural events. Using the same process, Molloy realized he could apply the same technique to capture clouds as the day progresses. After stacking multiple exposures of the same landscape, the changes in the sky make feathery brushes strokes across the sky.