The "Greenhouse Effect" A greenhouse is a building made of glass that allows sunlight to enter but traps heat inside, so the building stays warm even when it's cold outside Because gases in the Earth's atmosphere also let in light but trap heat, many people call this phenomenon the "greenhouse effect" The greenhouse effect worksThe greenhouse effect has kept the Earth's average temperature a good deal higher for billions of years, making it possible for life as we know it to evolve Over the past several millennia the average Earth temperature has been about 15 °C (59 °F) The figure below illustrates how greenhouse gases keep the Earth warmer than it would beA greenhouse stays warmer than the air outside Instead of cooling off at night, it traps some of the heat inside to keep the plants warm
Climate And Greenhouse Effect Umweltbundesamt