Cleric Cloud subdomain:
Thundercloud (Su): At 8th level, you can, as a standard action, summon a storm cloud. This power functions as fog cloud except that creatures inside the cloud are deafened and take 2d6 points of electricity damage each round from the flashes of thunder and lightning. Once created, you can concentrate on the cloud to move it up to 30 feet each round. You can use this ability for a number of rounds per day equal to your cleric level. These rounds do not need to be consecutive.
At my table, there are two competing interpretations of this:
1) The storm cloud lasts only as long as you are willing expend your "number of rounds per day equal to your cleric level", and immediately dissipates when you don't wish to expend any more of those rounds. With your remaining rounds, you can summon and move a new cloud just the same.
2) Once you summon a cloud (using one round of your ability), the cloud stays and dissipates according to the fog cloud rules. No further rounds of your ability are expended unless you choose to spend one to move the cloud, as stated in the rules.
It seems to me that both of these interpretations are compatible with the "These rounds do not need to be consecutive" clause. The real question is: what is the duration of the fog cloud?