How does a greenhouse trap heat?
Visible light is part of a broad band of radiation called the “electromagnetic spectrum.” Visible light can easily pass through the glass of a greenhouse, but when it strikes soil, plants, water, and the ground, some of the light is absorbed and changed to a different type of radiation called infrared. You can’t see infrared energy, but you can feel it it’s also known as heat! Although visible light can easily pass through glass, infrared radiation gets blocked by it. As a result, the heat gets trapped inside the greenhouse, and, as long as new light keeps shining in, the temperature keeps rising. This is why on a bright, sunny day, the temperature inside a greenhouse can get close to 100 degrees F even when the temperature outside is freezing.
