Create new file (CTRL + N).Make sure you have default colors selected(key D). Filter -> Render -> Clouds.

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Filter -> Render -> Difference Clouds:

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Adjustments -> Levels (CTRL + L). Adjust levels to something similar to this:

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My result is this:

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If you want to color this texture, use Adjustments -> Hue/Saturation (CTRL + U). Colorize must be selected. Here is what it might look like.

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