The photo above shows the Alcázar protruding through a soupy fog in Toledo, Spain . It was snapped just before sunrise on December 24, 2015. All but the tallest buildings in Toledo were consumed by the fog. If the temperature and the dew point temperature of the air is the same, fog will form. Though only a few feet thick, this fog was dense enough to severely limit the street-level visibility. In general, the visibility is poorer if more cloud condensation nuclei are available and if the fog droplet sizes are smaller. The Alcázar was used as a Roman palace during the 3rd century A.D.