There actually is a smell....although it is very faint. When a cloud comes off of a low-pressure system and brings the percepitation levels with it, it sets up a rainy session. There is actually a checmical reaction that natually occurs that allows the rain to seperate itself from to low-pressure of the perecpitation filled cloud, to the high-pressure that is prelavent on the ground. When the two pressures meet they form a positive Ionization Potential which releases the oxide vaporization which finally causes the Isotopic Mass to be released giving a physcial body. This starts the rain, and the reaction of this is, of couse, rain drops and a faint smell scientifically called Actinide. Which is what you smell.
by the way...I totally made all of that up.
Kinda bored up here in Canada.