"Cookie Monster: Hey, you know what? A round cookie with one bite out of it looks like a C. A round donut with one bite out of it also looks like a C! But it is not as good as a cookie. Oh, and the moon sometimes looks like a C! But you can't eat that."
– "C is for Cookie," Sesame Street
– "C is for Cookie," Sesame Street
Think about cloud-watching. If you lie on the ground and look up at the clouds, maybe you imagine that one cloud is shaped like a mound of mashed potatoes on a plate. If you board an airplane and fly to this cloud, you will still see some resemblance between the cloud's surface and the fluffy, lumpy texture of hearty mashed potatoes. However, if you could slice off a piece of cloud and examine it under a microscope, you might see ice crystals that...