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Re: (meteorobs) Question on Cloud!!
Kim Hay wrote:
>>if there is high cirrus cloud coming in and it covers your area
>>intermitently, how do you judge the obscurity percentage?
And George Zay responded:
>If the sky was uniformly covered...
>If the sky was intermittent...
Like in the old Microsoft joke, this is all true - and doesn't answer the
question. What you describe is a tough situation, Kim, and I see it pretty
frequently over this way, too - like last night for instance!
The sky on these nights ISN'T uniformly thinly covered, but nor is any part of
it necessarily "obscured", in the sense of being invisible! Instead, the LM
over different areas of the sky might be varying by a magnitude or more, and it
will change on you from minute to minute!
The easy answer to this, like in the old DOCTOR joke, is "Don't do that!" In
other words, only observe when conditions are pristine, and there's no sign of
any cirrus, cirrostratus, haze, mist, fog, or smoke.
For our lucky so-and-so friends with access to the high Southwestern desert,
I'm sure that's good advice - but for you and me, this is more like saying
"Don't bother to observe, kiddo." :)
I personally have only one approach on these nights: I do my LM estimates in
SEVERAL areas of the sky, not just the zenith, and then average all these
later. This is non-standard though, and I couldn't say how it might prejudice
analyses with my data later...
So how about it, folks - any better advice for these too-frequent situations?
Lew
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