It sure is warm in here, said Harlan. It sure is, said Blurtso. That’s because a greenhouse, said Alex, turns solar energy into thermal energy, which in turn creates a convection process. What? said Blurtso. Solar energy, said Alex, passes through the glass and gets absorbed by the ground and plants. The plants convert the sun’s short wave infrared rays into long wave infrared rays—into heat energy—which can’t escape the glass. Because the air is trapped, the warm air near the ground rises and the cool air near the ceiling falls, turning the greenhouse into a convection oven which forces the air to become warmer and warmer with each rise and fall. A convection oven? Said Blurtso. Exactly, said Alex. Does that work on a small scale? said Blurtso. Of course it does, said Alex. So I could bake a pumpkin pie, said Blurtso, in a miniature greenhouse?