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Predicting seeing conditions?


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Greetings wisdom-givers,

I'm sure old hands will have a good feel for how seeing conditions are going to turn out. We've been having lots of sun in the last week or two and I'd been keen to get the scope out.  First real chance last night, had some great views with the bins over the last couple of weeks, so got the scope out expectantly.  No clouds, no moon to speak of, but unusually bright skies (light pollution from nearby town more intrusive than normal).  Cygnus was dull, Altair was struggling, and I was thinking 'what the...'

I have had intermittent low cloud nights which have given vastly superior seeing...so, I'm wondering if there is, or anyone has done some kind of correlation chart between seeing conditions and standard weather data? Obviously there are many variables.  I check the BBC weather for my locality everyday and it gives data on: wind speed, humidity % . visibility :p , and and pressure millibars .

I was just wondering if anyone has connected things like pressure, humidity saturation etc, with optimal seeing conditions? 

I'm sure experienced hands will be able to just poke their heads into the garden in the morning and know how the night will turn out...but I'm becoming more perplexed!!

cheers

Jeff

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I'm not great at reading weather forecasts I must say, but I have noticed a few things relating to both seeing and transparency.

Nights which appear to have high haze and not great transparency often turn out to be excellent for planetary seeing. Conversely the very clearest nights can be quite unstable, perhaps because the earth is cooling more quickly. These nights are great for DSO observing at low to medium powers.

Last thing, observing after recent rain is often very good as the rain has cleared all the pollutants from the atmosphere and it is much clearer. What the seeing conditions are like though is a little hit and miss, but some of my best nights have been in these circumstances.

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and me too, thanks for sharing the Peach article - that is exactly the kind of thing that's been troubling me.  Very interesting that he shows the 'same' sky can have very different atmosphere/turbulence just given a change in position.  Astronomical observing just got more involved for me!

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I'm not great at reading weather forecasts I must say, but I have noticed a few things relating to both seeing and transparency.

Nights which appear to have high haze and not great transparency often turn out to be excellent for planetary seeing. Conversely the very clearest nights can be quite unstable, perhaps because the earth is cooling more quickly. These nights are great for DSO observing at low to medium powers.

Last thing, observing after recent rain is often very good as the rain has cleared all the pollutants from the atmosphere and it is much clearer. What the seeing conditions are like though is a little hit and miss, but some of my best nights have been in these circumstances.

...thanks! more wisdom one can't buy!

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Nights which appear to have high haze and not great transparency often turn out to be excellent for planetary seeing. Conversely the very clearest nights can be quite unstable, perhaps because the earth is cooling more quickly. These nights are great for DSO observing at low to medium powers.

Yup, that hits the nail on the head. My best planetary views have been through a high haze that I almost didn't go out due to.

The only forecasting things that I've found are:

  • High pressure is good (less cloudy)
  • Jet stream is bad (poor seeing)

Other than that, I use a weather forecasting stone.

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