Quote Originally Posted by guyanonymous View Post
Would the increase in matter result in an increase in atmospheric pressure?
If the matter becomes gas in the atmosphere, then yes. Our atmosphere is mostly free nitrogen, about 1/5 free diatomic oxygen, plus tiny little trace gases like argon.

But you can have anything you want in your comets ... just plain water and dirt would be fine, and if they don't bring in any atmospheric gases, then there's no increase in air pressure ... okay, maybe a little, due to the increased water volume ... I'm not really sure, to be honest. I kinda doubt it. Google for "vapor pressure" though. I once tried to figure the vapor pressure for neon on Pluto ~ omg I'm such a geek.