The power of Smart Ob jects
Smart Objects are something you can get by without, but once you start using them they make all kinds of tasks so much less troublesome. Converting a layer to a Smart Object wraps it in a protective bubble so that anything you do to it remains non-destructive. You can, for example, resize the layer multiple times with no loss in quality, or apply editable filters. This is useful for the Radial Blur filter used here on the clouds, as it can be difficult to judge the effect the first time round.