Greenhouse Effect Demonstration
The yellow arrow in the above diagram shows the heat radiation from the Sun coming down toward a greenhouse on the surface of the Earth.
The Sun's energy enters the Greenhouse
Because the Sun is so hot, the radiation can easily get through the glass panes of the greenhouse.
The Sun's energy is absorbed and re-radiated
The inside of the greenhouse absorbs the Sun's radiation and starts to heat up, producing radiation of its own.
The re-radiated energy is trapped
However, because the inside of the greenhouse is much cooler than the surface temperature of the Sun, it produces a different sort of light (infra-red) that does not pass through glass so easily. Thus the heat gets trapped inside.