Convection takes time to occur, and incoming radiation still exceeds outgoing radiation. Explain how radiational cooling produces a radiation temperature inversion. At the surface at night there is no incoming radiation from the sun and the surface begins to lose its heat to the air above. The air above then becomes warmer than that of the surface, thus producing an inversion. Remember, inversion means warm air above cold air.
Water has a greater heat capacity than dry ground.
Thus humid regions tend to moderate the temperature range. On clear days the earth can warm quickly and cool quickly when the sun goes down. On cloudy days the clouds absorb the heat rising from the ground and reradiate it back down to help moderate the temperature. As in the previous answer. Two cities have the same mean annual temperature.