Ahh, but now we get into the interesting question:
While the call lightning is still up, can you cast a dispel magic on a creature that was injured by it, to dispel the damage? (Of course not.) Does the damage go away when the spell ends? (Of course not.)
So we have this intuitive knowledge that something like "spell does damage to creature" results in damage which, although caused by magic, is not itself a magic that can be dispelled. But so far as I can tell, it's only ever explained under the "instantaneous" rule, which doesn't really apply to Call Lightning.
While the call lightning is still up, can you cast a dispel magic on a creature that was injured by it, to dispel the damage? (Of course not.) Does the damage go away when the spell ends? (Of course not.)
So we have this intuitive knowledge that something like "spell does damage to creature" results in damage which, although caused by magic, is not itself a magic that can be dispelled. But so far as I can tell, it's only ever explained under the "instantaneous" rule, which doesn't really apply to Call Lightning.