Slide 35 in this series.
Trends of clear sky, as with the data below, can show how the trends in clouds has occurred. The interesting aspect of this data is that the higher the clear sky the warmer the earth might be. And in this case the increase in clear sky from 1987 to 2000 is when the earth was warming. Since 200 the temperature has been more constant.
NEXT: Cosmic rays do affect clouds, our next stop.
These links are the topics for this section.
Modelling Temp Natural Factors
Earth and the Science of Radiation
Milankovith Overlapping Cycles