A tutorial on using the Gradient tool to add impact to skies in landscape images – with the advantage of smooth transitions
On an open image of a landscape and create a blank layer (Cmd/Ctrl+Shift+N). Press D for black and white foreground/background swatches, and select the Gradient tool (G).
In the Options bar set the style of gradient to Foreground to Transparent (second option in). Keep the Opacity set to 100% and make sure Dither and Transparency are ticked, but not Reverse.
With the tool setup, click and drag a line from the top of the sky and down to the ground. If the gradient goes over any land areas, Cmd/Ctrl+Z and then try angling the line slightly off vertical.
At the moment the sky is covered in black. This is where blend modes come in. Change this layer’s mode to Overlay and watch how the black is blended into the lighting of the sky, adding contrast and drama. If image quality has suffered a little from using Overlay, lower its opacity to around 80%, or change the mode to Soft Light.