I don't need to because I've played the damn game to death, with and without mods. You're dead wrong. The fact that it looks different does not change the fact that it acts in the same way gameplay-wise. When you cast an on-target spell in Oblivion, no matter the effect, it spawns an entity that travels to where you are aiming and applies the magical effect upon whatever it hits. Making it an AoE spell simply applies the spell effect in a radius of X feet from the point of impact, X being the magnitude of the area effect you specified. Did you ever watch NPCs cast Frost on-target effects in Oblivion? It throws a cloud that is visually bigger than the actual spell that hits things. Not a cylinder.
I have no idea what game you've played, but I've played Oblivion myself and have cast all the elemental spells in area-of-effect form. Fire travels as a ball and explodes on contact, out to the area of effect, in a sphere. Shock travels in a bolt until it passes within range of a target, then it jumps to that target, then to any other target within range. And frost travels as a cylinder the size of the area of effect and hits anything within that cylinder, regardless of distance from the caster.
Seriously - go play the game. I'm not making that up. I've done it and watched it happen. We discussed it on the Oblivion board years ago and experimented with it, discovering, for instance, that if a spell combines effects and has one of the elemental effects as the most magicka intensive, then the game uses that animation, making it possible to cast other effects in the same manner - jumping from target to target if the dominant effect is shock or hitting multiple targets regardless of distance if it's the frost effect or what-have-you.
I'm not kidding - I'm not making it up - I'm not wrong. Just go try it and you'll see.
"Frost damage has a Fog projectile, as opposed to a Bolt like Shock Damage or a Ball like Fire Damage; Unlike the other two elemental damage effects, the Area of a Frost Damage spell dictates the size of the actual projectile, not simply the size of the explosion upon impact, and all targets caught inside the projectile's flight path will be affected by the Frost Damage. The projectile fog also lingers for a short time after impact, damaging anything that passes through it. This makes Frost Damage the most effective way to damage as many foes as possible with one cast."
http://www.uesp.net/wiki/Oblivion:Frost_Damage
:D Thanks. I should've thought to just go to UESP.....