High earnings usually mean that you were lucky that someone clicked on an advertisement worth 1 dollar.
Sometimes you are lucky and people clicks on the right ad thats all. I have sites with an average click that gives >0,1 but sometimes i got clicks that gives me more than 1,5 $ and thats just because different ads are displayed and people hopefully clicks on the right links
It is difficult to determine what factor is responsible for something like sometime. That is a good earn to start the day, good luck.