here is the best explaination I could come up with:Bobby Drake could be, potentially, one of the most powerful mutants on the planet. Look at his power. People say "Ooh! He makes ice." Or now, "Ooh, he turns himself into ice!"
But let's step back. Basic physics says that there's no such thing as "cold", as a quantative energy form. Only degrees of heat. "Cold" is a relative term, requiring a difference between the observed target and the temperature of the observer. Example: I'm standing in my office, at a nice 73 degrees. The cabbie outside is standing on the street, shivering in 40 degrees. To me, he is cold. Whereas if I were buried in snow (great shades of this past weekend) at around 20 degrees, I'd consider him pretty warm.
Right then, we've established that there's no such energy form as "cold". So, Bobby doesn't generate cold to form his ice, and he doesn't generate the moisture himself (imagine how quickly he'd be dehydrated). Therefore, he forms his ice structures from the ambient moisture in the environment around him. To do this, he causes the moisture to freeze.
But how? We know he doesn't "project cold", so then he must absorb or dissipate the heat. By the laws of thermodynamics, energy is constant, it cannot be created or destroyed. However, let's go to another scientific principle. Heat is a measurement of the internal kinetic energy of an object. The more those atoms and molecules are buzzing around, the hotter it is.
What Bobby Drake does, as I see it, is project a field that inhibits the motion of those particles (herein referred to as Brownian Motion) thus dropping the temperature and freezing the moisture.
However, the amount of water vapor in any given area is not consistent with the large stunts Bobby regularly pulls off (re: ice slides, ice walls, etc). If he were to coalesce that much water vapor in one place and freeze it, the humidity all along the Eastern Seaboard would drop dramatically, we'd have wildcat lightning storms all over the place, cats and dogs living together, it would be anarchy, you see my point.
So that extra frozen mass has to come from somewhere. Remember that water vapor isn't the only thing in the air. You have a mixture of all sorts of gases. One of the most prominent of these is carbon dioxide. Compared to the other prominent gases in our atmosphere (nitrogen, the most common, and oxygen), carbon dioxide has a relatively high temperature (although still incredibly low) at which it becomes solid. It is my theory that the most part of Bobby's ice structures are composed of frozen carbon dioxide, or "dry ice". This would also explain why Manhattan isn't flooded every time his ice slides melt, since most of it sublimes back into gaseous carbon dioxide.
So, what Bobby does is inhibit the Brownian Motion of objects. He can do this so quickly that there is no expansion of the target's water content, as was seen when he flash-froze Legion completely. Had he merely frozen all the moisture in Legion's body, well... put an unopened can of soda in the freezer sometime. Wait a few days. Watch the results. Legion would be a messy red chunk when he thawed.
Bobby is an incredibly powerful cryokinetic. But that's not the only extent to his powers. Since Mikhail's fiddling, he can transform his entire body into a water-based organism. In his form of homogenous ice, his thought processes go on, even though water is a MUCH less efficient conductor than neurons in the human brain. Basically, Bobby converts all the molecules of his body into water, and freezes and molds it as he moves. He has the capability to assume a completely liquid form (as Emma Frost did when in control of his body) as well as the potential ability to 'teleport' by zapping his consciousness through water vapor in the atmosphere, reforming at his desired location. In AOA, this was referred to as "moisture inversion". And through all this, he retains the ability to resume human form.
Let me get to why I think he's an Omega-class. Ever see that Star Trek:TNG episode where the alien evolved into a sentient life form? The premise was that eventually, all organic beings would 'evolve' into a more efficient sentient energy-based lifeform. We've seen some mutants that already do this.
Chamber
Malice
Shard
Onslaught
As well as some non-mutants, like the Living Laser, Living Lightning, etc. Bobby falls into this class of 'evolved' beings whose consciousness resides in an energy-based state. He just hasn't realized it yet. Canonically, we've heard it referred to multiple times that Bobby hasn't realized his full potential. Imagine what he could do with realization and training.
Create a 'giant' ice form with corresponding strength and stability.
Create and animate multiple ice forms.
Coalesce all the water vapor in an area into a superdense solid, dropping the humidity rapidly, resulting in chaotic weather effects, mass electrical storms, etc.
Acting as a catalyst for superconducting machinery (we've already seen him do this).