It's cold!

While it really is cold outside that's not what this entry is about.  When people say "It's cold," everyone knows what they're trying to communicate and they all grumble in agreement as they snuggle deeper into their parkas and sweaters, but what does "It's cold," really mean?  What exactly is "it"?  The listeners are provided with a pronoun devoid of an antecedent.  Possible antecedents could be as follows: "The air is cold." "The rain is cold." "My flesh is cold." What if all three were cold? One would still say "It's cold." Why not "They're cold?" Isn't that correct grammar?

Sometimes people add an "outside" on the end making the obvious statement, "It's cold outside."  Now the listeners have been given a preposition standing alone without a prepositional phrase.  To be more correct, the chilly chatter should specify exactly outside of what or where it is cold. "It's cold outside the building." "It's cold outside of my bed."  "It's cold outside of the volcano." Well it's actually probably still warm right outside the volcano, but you get my point.  

In addition to "It's cold," we also have "It's hot," "It's stuffy," "It's uncomfortable," "It's all good," and so on and so forth.  So I guess the question I'm posing is what is this omnipresent "it" and how is "it" so diverse to encompass all of these adjectives? Alas, it will always be a mystery. :P