[AZ-Observing] Re: Midwestern Definition of Clear

Tom Polakis wrote:
> I have noticed over the years that many amateur astronomers east of the 
> Mississippi River are not impressed when I tell them that one night in 
> three is clear in Arizona. [edit]

Having lived 20-years in Wisconsin before moving to Arizona, I can't imagine 
a Midwesterner not being genuinely impressed by that statistic. Anybody who's 
lived through one winter--let alone 20--east of the Mississippi *knows* that 
one night in thirty is the typical clear ratio during much of the year. And 
that one night is likely to feature below zero temps and gusting winds.

Wanna know why Midwesterners look so young? It's the daily face peels we get 
walking into the teeth of a winter wind.

As for the rest of the year, the clear night ratio may be better but even a 
clear night doesn't mean a good night. The photo in Tom's picture shows a 
typical clear Midwest sky at sunset during the summer. The only thing missing 
is the Wisconsin State bird, a blood engorged mosquito that makes a B-52 look 
like a Cessna. As the photo illustrates, a clear sky doesn't necessarily mean 
good transparency. Any time devoted to the sludge, which passes for sky, 
within 15-degrees of the horizon is pretty much a waste of time.

September was my favorite observing month in Wisconsin. You could pretty much 
count on five to seven clear nights in September. The combination of lower 
humidity (40% to 50% is *really* good, out there), lower temps (equals fewer 
mosquitoes) and longer nights made fall observing in the Midwest a true joy.

Still, it's no match for the desert southwest.

Being able to observe right to the horizon is what immediately impressed me 
about northern Arizona skies. As is often the case with people who've not 
experienced a true dark sky, I was not impressed by the darkness--or lack 
thereof--of the Arizona sky. It seemed too gray, not "inky black" as pristine 
skies are often described. Soon enough, I came to realize that a true dark 
sky is pretty bright what with all those thousands of stars that can be seen. 
"Inky black skies equal good skies" is one of those myths that needs to be 
euthanized.

In Arizona, the seeing's better, a clear sky almost always means excellent 
transparency, some southern sky jewels are within reach and there are a lot 
more nights when it's clear.

Anyway getting back to Tom's comment, I suspect the Midwesterners who shrug 
their shoulders at "one night in three" are either in denial, taking a stiff 
upper lip attitude, or aren't out with scopes enough to understand how 
significant such numbers are.

Where I come from, one in three is pretty damn good.

Regards,


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