The storm was really giving it everything it had. This was its big chance. It had spent years hanging around the provinces, putting in some useful work as a squall, building up experience, making contacts, occasionally leaping out on unsuspecting shepherds or blasting quite small oak trees. Now an opening in the weather had given it an opportunity to strut its hour, and it was building up its role in the hope of being spotted by one of the big climates.
Terry PratchettGranny Weatherwax was often angry. She considered it one of her strong points. Genuine anger was one of the world's greatest creative forces. But you had to learn how to control it. That didn't mean you let it trickle away. it meant you dammed it, carefully, let it develop a working head, let it drown whole valleys of the mind and then, just when the whole structure was about to collapse, opened a tiny pipeline at the base and let the iron-hard stream of wrath power the turbines of revenge.
Terry Pratchett