Give reason:

Cloudy days are warmer than cloudless days.

The clouds in the atmosphere act as a barrier from heat. If the sky is clear the heat emitted from the earth’s surface feel free to escapes into the upper skies or space resulting in the cooler temperature. But when there is a cloudy sky, the clouds act as a barrier to the heat trying to escape and thus leading to a warmer atmosphere. The heat emitted from the earth’s surface is trapped by the clouds and reflected back to the earth’s surface.