Re: [APML] Water Vapor and Transparency

[Aplanatic@aol.com]

Hi Chuck:

I spend a lot of time in the Eastern Mojave these days.  When I come back I often check the GOES 10 archives:

http://www.goes.noaa.gov/search102.html

I find that several things correlate with good seeing and good transparency:

1)  This time of year, if the general flow is from the WSW then its more likely to be very clear with good seeing than if the flow is from the SSE (monsoons) or NW (typically bad seeing for us).

2) If the water vapor map shows low water vapor, then this is generally a good sign, but, as you say, not definitive. 

3) Of course, if the visible channel shows clouds or haze, then the transparency will generally be poor.

So, in order of importance for my location, I first look for the flow direction (best flow direction is a function of the time of year), then the visible channel, then the water vapor channel.  I still don't know if or how IR is correlated with good observing or photographic conditions.  Any comments?

I agree that dust (and maybe even smog from LA, yuck) seems to be a major cause of degradation of transperency, at least where I'm at.  This is most prevalent in May, June and eary July.  In the fall, winter, and early spring the eastern Mojave ususally has great transperency but the seeing can be good or bad depending on the upper level wind direction and location of the jet stream.

Interesting topic, thanks.

Dave Rowe



--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
             Unsubscribe at <majordomo@seds.org>