Book 29, Question 88
How does a greenhouse stay warm?
A greenhouse has walls and a roof of glass or clear plastic.
Sunlight passes in and warms the plants, soil, and air. The glass mostly stops that warm air from escaping or mixing with the cold outside, and the walls stop wind from carrying warmth away. This keeps the greenhouse warmer than outside. On sunny days, vents must be opened so plants don’t overheat.