What causes a cloudless day?
What causes a cloudless day? Even when it is very warm and sunny, there might not be any clouds and the sky is a clear blue. The usual reason for the absence of clouds will be the type of pressure, with the area being under the influence of a high pressure or anticyclone. Air would be sinking slowly, rather than rising and cooling.
Does clear skies mean no clouds?
Clear skies are just the opposite. The absence of clouds in the sky means that the dark blue sky vault reflects much less light than the overcast vault. The sky vault portion of the clear sky is brightest at the horizon and darkest at the zenith, typically at a ratio of 7:1.