[AZ-Observing] Re: Seeing Conditions During Monsoon

AJ, Brian, et al;

I do remember hearing that the cells that effect seeing the most are not
high in the atmosphere, but actually are only 10 feet or so above your =
head.
I have no idea where I heard that, it is information from many years ago =
and
I just don't remember the source, sorry.

But, our experiment while the star was being occulted by Saturn =
certainly
seems to provide information that would support the "close by" theory of
fast seeing.  Maybe there are two effects, one close by and one far
overhead.

Of course, none of this matters when the storm is overhead raining on =
your
telescope;-)

Clear Skies to us all;
Steve Coe


-----Original Message-----
From: az-observing-bounce@xxxxxxxxxxxxx
[mailto:az-observing-bounce@xxxxxxxxxxxxx] On Behalf Of Derrick Lim
Sent: Monday, July 23, 2007 10:46 PM
To: az-observing@xxxxxxxxxxxxx
Subject: [AZ-Observing] Re: Seeing Conditions During Monsoon

Hello AJ!
That's a very interesting study. The results say that the turbulence =
cells
dictate the local seeing conditions. Therefore something I neglected in =
the
list is the size of the turbulence cells, how would they distribute over =
the
Phoenix area, or perhaps more generally, what affects the size of these
turbulence cells? Can anyone please help explain this?  Does this have
anything to do with cooler air in the upper atmosphere "shearing" off =
layers
of warmer air in the lower atmosphere? (or am I way off the track here?) =
If
so, perhaps wind speed would be a factor in determining the cell size, =
then
maybe there's a threshold wind speed in the upper atmosphere that can be =
one
gauge of seeing conditions.

Hope I'm not beating a dead horse here... :)

Derrick


On 7/23/07, AJ Crayon <acrayon@xxxxxxx> wrote:
>
> Something similar to what Derrick suggests was done on the evening of =
July
> 2, 1989.  Six observers, myself and Steve Coe included, lined up at =
the
> same
> site to watch Saturn occult the star 28 Sagittarii.  We watched this =
event
> for about one hour and each described the view - out loud for all to =
hear.
> We were set up in a line about 15' to 20' apart.  One of the important
> reports turned out that the seeing effects came and went independent =
of
> telescope observer.  That is, while one observer reported seeing so =
bad
> Cassini's Division wasn't visible.  At the same instant another =
observer
> saw
> the rings crystal clear.
>
> What we decided was that the cells of warmer air, causing the =
turbulence,
> were much smaller than realized.  Perhaps as small as a foot.
>
> Clear skies,
> aj
>
>
>


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