An example of what Tinstaafi has explained is when cloud covered nights are often milder than clear cloudless nights.
The conduction and subsequent convection process lags behind the actual sun position i.e. it takes time for the sun to heat the ground and then convect to atmosphere. This is why the warmest part of the day is normally mid afternoon and not at midday when the sun is at its highest. This means that the surface continues to convect warm air to atmosphere after the sun has set. With full cloud cover during the night, the warm convected air is kept in the lower levels of the atmosphere because the cloud cover acts as a shield. With little or no cloud cover, the milder air is free to dissapate through much greater depths.