If you’re wondering how to replace a sky in Photoshop, choosing the correct sky to Composite into your photo is the most important step in Compositing a sky. There are a few different factors you will want to keep in mind when looking for a new sky.
Position of the Sun – Make sure the sun is in the correct position in the Composite sky, it should mirror the position of the sun in the original image.
Atmosphere – If the original image was taken on a cloudy day, don’t try to add a bright sunny sky, the Highlights and Shadows will look completely different.
Initial Color – Although you can easily Change Colors in Photoshop it is important to Match Colors as close as possible. The reason is that the Colors of the sky change the Colors on land. Also the sky looks very different during an orange sunset than on a bright sunny day. Even if you change those Colors, the Texture of the sky won’t look right.
Make Masking Easier
Most of the time your horizon will be bright, even if you are not Compositing images together. Keep that in mind when Compositing a sky and your job will be much easier. If you have a Light sky, simply apply a gradient Layer Mask and hide the bottom of the replacement sky. If you have chosen your sky well, the Transition should look natural. After the Transition is made try altering Exposure and Color using Curves. If you have anything in your image that you would like to show up over the sky(birds, trees), set the layer blending mode of the sky to “Multiply” to let those objects show through.