Hi Steve,
Quote:
Originally Posted by figgylion
Now I understand what is meant by this in visual terms but I was wondering if one of you helpful people could explain what determines good/bad seeing?
What I mean is what makes the seeing good or bad. Obviously cloud cover, light pollution, dust & smoke make for bad seeing. What conditions would make for good seeing? High/low temperature, dry/humid, atmospheric pressure,winds or lack of, time of night or even year?
Are there any weather patterns to look out for(good or bad)?
As I've only been serious with Astronomy for about six months ...
Cheers
Steve
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I've never been serious with astronomy, its not a prison sentence ...
Obviously cloud cover, light pollution, dust & smoke make for bad seeing.
No, not really. In a nutshell (so far as I'm able ...)
The list you have made here relates to
transparency in other words how see-through the atmosphere is. Good transparency means the sky is, well, transparent and dark. Some poeple count
sky-darkness as a separate thing to transparency but I think this just over-complicates things.
Seeing is how
steady the atmosphere is which results in fine detail being easy to see and smaller star images in the telescope. Bad seeing will make the star images look bloated and wobbly and or like tennis-balls. Equally, planetary images look washed-out, fuzzy or wobbly.
In good seeing, the star images even at high magnification look small, intense and sharp. Planetary detail is more abundant and easier to see. Much higher magnifications can be used without the aesthetics of the image deteriorating.
There are basically two different types of bad seeing that have different causes.
fast seeing is caused by high-velocity winds high in the atmosphere that make star images look like a tennis ball. Take a look at the jet-stream maps on the wether sites. A jet-stream passing overhead is bad news and will make bad fast seeing.
slow seeing is generally caused by the air much lower or even the movement of air inside the 'scope. It generally, or in effect causes an otherwise reasonable or good image to slowly ripple and wobble.
Without writing a whole essay, that's the summary. And noooo, it isn't a stoopid question at all.
BTW, like the sign-off quote.
To complete ... "You might think its a long way down to the chemist but that's just peanuts to space. Listen ..."
Best,
Les D