1. The Greenhouse Effect

2. A greenhouse is a building used to grow plants when the outside temperature is too low. The roof of the greenhouse prevents convection by trapping warm air inside.

3. The Greenhouse Effect The heat from the sun has a lot of energy and easily passes through the glass into the greenhouse. Heat from inside the greenhouse has much less energy and is reflected back into the greenhouse.

4. 240W of heat from the sun reach each square meter of Earth’s surface. Some is absorbed, and some is reflected back into space. 103W of heat are reflected by the atmosphere. 168W of heat are absorbed by the ground. A large amount of heat travels from the sun to the Earth, The incoming energy is about 343W per square meter of Earth’s surface. 72W/m 2 are reflected by Earth’s surface 168W of heat are reradiated by the ground as long-wave infrared. 168W of heat escape into space after being reradiated. Greenhouse gasses absorb and reradiate some long-wave infrared. This causes the heat to take longer to get back into space.

5. The Greenhouse Effect Picture the heat coming in from the sun as the water flowing from a tap into a sink. The water going down the drain represents heat radiating back into space. The amount of water in the sink represents the temperature of the atmosphere.

6. The Greenhouse Effect Greenhouse gasses like carbon dioxide, methane, and water vapor slow down the heat that is radiating back into space. It’s like putting a glass under the tap. It doesn’t change the amount of water going out, but it does hold more water in the sink. Without the greenhouse effect, Earth’s atmosphere would be about 30ºC cooler.

7. The Greenhouse Effect Humans activities are adding large amounts of greenhouse gasses to the atmosphere. Carbon dioxide in the atmosphere has risen 10% in the last 25 years, largely through our use of fossil fuels. We are making the glass bigger.