Adding smoke, haze, or atmosphere can give your scenes a lot of much-needed depth when you add lighting, but if you want to turn that stuff into thick, scary movie-style fog for a spooky scene, it's not going to happen all by itself. Luckily, Jay P. Morgan of The Slanted Lens has a simple and inexpensive solution for those wanted to create low-lying fog, and all you'll need is some ice and a cooler.
The trick to getting smoke that is pillowy, thick, and stays close to the ground is keeping it cool.
Though this is a simple DIY solution, it does take a little elbow grease. Morgan cuts a couple of holes on either side of the cooler and screws dryer vents onto each one. This not only makes it easier to attach stuff to the holes, but it makes it look 1000 times better.
After that, place a small block of wood in each corner of the cooler and then set a metal grate right on top. This will allow you to put your dry ice on top, let the fog from the dry ice fall to the bottom of the cooler, and then exit through the pre-cut hole.
And that's really it. Just put your smoke machine against one of the holes in the cooler and you're golden. If you want to distribute your fog easier/further, attach a dryer vent hose to the other hole.
Source: The Slanted Lens