In your comment above you allude that the clouds don't react properly to the direction that aard is being cast, thus backing up your idea that it's distortion. As if video game physics were as lawful as real life physics, but they aren't. It's just simple lines of code and scripts, IF this happens, then this should happen, etc. It's easy to imagine either purposeful or unintended effect when using this ability, Aard, that has an entire function built around effecting the environment around you, whether that's ripples and waves on water, grass, blowing out fires, or moving items in the game world like boats and barrels. We can even ignore the physical effects aard has on the game world and see that the ability has many lines of code dictating what it can do when cast, probably moreso than other abilities, and that level of complexity makes the likelyhood that a bug is burried in the code more likely. Honestly I don't think Aard is physically and intentionally affecting the clouds in the sky at all. If you watch the above video and the one I posted lower in the comment, it simply seems that the speed of the clouds is sped up when casting aard.

Literally the only part of the video in which the clouds appear to be moving, is when he looks up around the 7 second mark. You know why?

Because that's where the clouds are closest to the player character, and the axis of direction in which the clouds are moving is most pronounced when viewed from that angle? Thus making it easier to spot movement. The further away clouds when you pan the camera to the sides of geralt move either further away from Geralt or closer to him, and when viewed from that angle, would be harder to spot any movement. Do the clouds move up and down in the sky when you're looking in front or to the sides of Geralt? No they move closer or further away from him. When panning the camera up, you completely change your perspective of the clouds and the way the move, they move acrossed your field of vision from this perspective, they do not not shrink or grow larger like when viewed from the front

Here's another video of someone who discovered the effect,

https://www.youtube.com/watch?v=8C1ZfjJwgwU

And I just jumped into my game to see the effect myself. The clouds move very slowly in the game. The time it takes the edge of a cloud to meet the edge of my screen, when not moving the camera an inch, is much longer than when I loaded that same save, positioned the camera and the cloud in the same spot and started casting aard. The clouds in the skybox are momentarilly sped up when casting aard is the only conclusion I can take from that.