Meteor Swarm, the typical level 9 damage spell.
The Air elementals get cone of cold 3/day. Dice-wise, that's capable of doing 45d6 of damage (over 3 rounds, mind you, and assuming HD is 15)
Meteor Storm does 4 spheres of 2d6+6d6, which deals 32d6 of damage in one spell.
It's a repost from 339, but by summoning a single air elemental and having it cone of cold constantly, you can get more mileage out of your spell compared to, say, Meteor Swarm. Summoning multiple elementals makes this even better, of course.
I'm pretty sure that's what that little note meant.
Did I just read you saying "This lower level spell does more damage than this higher level spell so it's better... assuming I can cast the lower level spell unopposed 3 times."?
I'm not disagreeing with your jist, but why don't you realize that's a shitty argument?