Analysis: Cloud cover and Temperature

What is the relationship between Cloud Cover and Temperature?

Is there a relationship between the amount of cloud cover and local temperatures?  When it's cloudy, is it warmer, or cooler?  Is it warmer when the skies are clear, or cooler?  Is there a relationship between these two factors at all?

Examine your data to formulate your hypothesis.  Look at the temperature of cloudy days, compared to the temperature of non cloudy days.  Is there any connection?  

When you have an answer, prepare your report for The Editor, using the Format Guidelines.  Be sure to include maps or charts to support your conclusions.