Climate #3: Blocking Thermal Radiation

How does the atmosphere affect thermal radiation? Well, for one thing, it can block it, trapping heat below. But when we have a cold, cloudless night sky, what happens to the thermal radiation? The two atmospheric elements which block heat -- water droplets (clouds) and carbon dioxide -- are not blocking the radiation as much. So, the cold night sky allows the thermal radiation to pass, cooling the surface of the planet.