When I had my really good Mars observations with the bit of I believe it was Jupiter was up, it was on one of those really late summer evenings with the lower cumulus clouds that formed a layer that seemed to steady out the seeing. These clouds as I recall were still pretty high up. It was a number of years ago. I think your right about the seeing always seems to be best before the coming of Cirrus clouds. Dwight In a message dated 3/14/2011 7:50:53 A.M. US Mountain Standard Time, tpolakis@xxxxxxx writes: ---- DBogan3220@xxxxxxx wrote: > Seeing can sometimes be much improved with high thin clouds present. Some > of my best visual impressions of Mars has been had this way. I know you wrote "sometimes," but I'm going to have to go ahead and sort of disagree you with there. All the planetary imaging I've done in the past few years have made me something of a student of seeing conditions. My observation has been that we often have good seeing in the hours before the arrival of cirrus clouds, but the seeing is always unsteady once they are in front of your target. On the other hand, seeing can be very good when lower cumulus clouds are in the area, as we see in Arizona during Summer. And seeing is often excellent on foggy nights, but that's not something we get a lot of in the Southwest. Tom -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list. -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list.