Rules question about cloud spells

[keen320]

I'm wondering, do cloud spells like fog cloud just make a cloud in their area of effect, or do they continue to spread? At first I thought the former, then something made me think the latter, but I don't really know, and I haven't been able to find an answer in a quick search.

Specific system is pathfinder, but I imagine it's the same between it and 3.5.

[eggynack]

Fogs stay within their initial range unless they say that they don't. For example, cloudkill (http://www.d20pfsrd.com/magic/all-spells/c/cloudkill) moves away from you at a rate of 10 feet per round.

[Lateral]

Unless they say they spread, then no, they stay in one place. So, for example, a fog cloud would stay in one place, but a cloudkill specifically states that it moves at 10 feet per round. Area doesn't change, though.