As fog cloud, but in addition to obscuring sight, the solid
fog is so thick that any creature attempting to move through it
progresses at one-tenth normal speed, and all melee attack and
melee damage rolls suffer a 2 penalty. The vapors prevent
effective ranged weapon attacks (except for magic rays and the
like). A creature or object that falls into solid fog is slowed,
so that each 10 feet of vapor that the creature or objects passes
through reduces falling damage by 1d6.
Unlike normal fog, only a severe wind (31+ mph) disperses
these vapors, and it does so in 1 round.