I've noticed that my adsense earnings at times increase as a result of just "impressions" and no clicks (even if it is only a few cents). Is this normal? And does Google pay it because there aren't clicks (adword users) to generate the income?

You also get per 1,000 of impressions (PPM).

I have got payout without clicks
it seems 1000 impression $0.01, sometimes $0.03 to $0.1

You might have to many ads this can cause a slump in profits I noticed it I had an ad at the top of every forum page 3000+ and an extra one on the homepage was making nothing I changed the top one to an ebay auction I was runing and my profits from the google ads started to fly up from then on I only have one adsence ad on the whole site on the homepage.

I think its like a mix together like the more impressions your site gets the more money you get per click like this is just a random number one click regular is 5 cents per but if you get like 10,000 impressions I think it will be like 70 cents a click thats not an exact thing but you should get what Im saying