Cleaning the awning, bubbles appearing

Actually guys, no, the section near the roof is relatively unchanged. The bubbles are spread across the lower section that is deeply rolled on the drum. The section that is bubbling is dark brown and gets lighter in gradient near the trailer. The white part nearest the trailer that is exposed virtually all year has no bubbles that I can detect. Some vague mildew between the plies is visible, but no bubbles. I am suspecting it's because the darker color absorbs more light and gets hotter. I have felt it on summer days and it gets pretty darned hot. Since I lost my Webshots hosting account (Grrrr!), I haven't signed up to anything else, so pictures won't be coming any time soon. I'll work on it.