Why Goolge Adsense Pays Some Websites More Than Others

The other day my earnings for my hip hop music blog (HipHopMusicDotCom.com) doubled, the funny thing is the traffic remained the same there was no spike and the amount of clicks I received wasn't any different from any other day, so what changed? I've learned that the earnings you make from Google Ads depend on the quality and the amount of ad inventory Google has at any particular moment in time and not on the amount of clicks your ads receive. My hip hop blog gets anywhere from 40,000 to 60,000 page views daily and I receive quite a few clicks but then my music video blog (MusicVideoCast.com) only receives on average 10,000 page views with far less clicks than HipHopMusiccDotCom.com but manages to match it's earnings.google-earnings
So the type of site you have also plays a role in the amount of Money you'll make with Google Adsense. For instance lets say I was running a blog about health care coupled with the type of traffic I receive to my hip hop blog, my earnings would most certainly triple what I'm making now because the ad inventory for health care is bigger and the amount of money advertisers are paying for those ads is much higher sometimes even as much as ten dollars per click. A simple rule of thumb to go by is the more money advertisers have to pay for keywords for a particular type of content the more money Adsense publishers will make if there site caters to that particular type of content.
Makes me wish I knew something about health care…..LOL