You can see how well distributed the aerosols are by having a look at the Kitt Peak webcams in late afternoon (like _now_): http://www.noao.edu/kpno/kpcam/index.shtml ...though, like in Flagstaff, some of that is regional brush-fire smoke mixed in. \Brian -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list.