Solid Fog

This spell functions like fog cloud , but in addition to obscuring sight, the solid fog is so thick that it impedes movement. Creatures moving through a solid fog move at half their normal speed and take a -2 penalty on all melee attack and melee damage rolls. 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 it passes through reduces the falling damage by 1d6. A creature cannot take a 5-foot-step while in solid fog . Solid fog , and effects that work like solid fog , do not stack with each other in terms of slowed movement and attack penalties. Unlike normal fog, only a severe wind (31+ mph) disperses these vapors, and it does so in 1 round. Solid fog can be made permanent with a permanency spell. A permanent solid fog dispersed by wind reforms in 10 minutes.