It's not the amount of traffic, it's the fit between your users and the advertising, how targeted they are, intent, etc etc.

Also it totally depends on the service/product. For stormpulse I don't think advertising supported is probably the right idea unless it's made more mainstream.

For example I'd start a "enter your email to get local weather reports free". Build up a massive email list, then start including promotional adverts at the top/bottom of each mailing. You'd be sending out a large amount of mails, to a large amount of people... I think it could generate a good revenue.

It's not as simple as slapping up some ads and going home. This is the mistake I think most people make.

It really depends on the targeting and matching the right ads to the right users. For example, weather.com gets well over $10 CPM from performance advertisers, and they still make money on the traffic. If you have similar demographics, you should be getting similar CPMs.