When you stand in sunlight, you feel warmer than when you are in shadow, so you can feel that light from the sun carries energy that can warm an object—you. You can feel the warming effect, even if the sunlight comes through a window before it hits you. In the same way, the soil, pots, plants, and so on inside a greenhouse, like the one pictured here, are warmed by the sunlight that shines through its transparent walls and roof. The air inside the greenhouse is then warmed by contact with the warm objects. If the door and ventilation windows are closed, the warm air can’t escape, so the temperature of everything in the greenhouse goes up.
