Fog is rendered as a box around the player, with the player facing one of the sides. This means that the player can see further at 45° angles left and right than in the centre of their view space. This means that you might see something in the corner of your eye in the distance, but then when you try to look at it, it fades into the fog.

Here is a diagram of what I mean.

Is there a mod or some other means of rotating the box so that your visibility is greatest in the direction you are looking?

Something like this.

Thanks!