Sunlight passes through the transparent plastic and heats the soil. A layer of water underneath the plastic retains the radiant heat at night through what is known as a greenhouse effect. Black plastic mulch absorbs most of the sunlight and becomes greatly warmed, and little energy passes through to warm the soil. These results support those of Ham and Kluitenberg (1994), Waterer, 1999 and Waterer, 2000, Tarara (2000), Lamont (2005) and Ngouajio and Ernest (2005) who showed that transparent mulch absorbs only 5% of short-wave radiation, reflects only 11%, but transmits 84% of short-wave radiation, whereas surface temperatures do not reach the levels found on black plastic due to their low absorption rates of short-wave radiation. That means that transparent plastics actually heat the soil by transmitting light to the soil surface rather than conducting heat like dark plastics.