‘Local’ seeing conditions - what does this mean?

[okiscopey (Mike)]

In another thread, someone mentioned ‘local seeing conditions’ as being one of the numerous factors involved in getting the best quality images, but I’m not sure exactly what this means.

For a given geographic location, and ignoring the prevailing light pollution from nearby towns, I assume it refers to heat and light sources (etc.) from one’s own or neighbouring properties. I’m aware that grass and trees are better surroundings that concrete, for example.

But are there particular combinations of terrain that should be avoided, or is there a ‘blacklist’ of particular geographic areas? If there is, please let me know so I don’t end up buying a property there!

[iceman (Mike)]

Hi Mike

Check out this article by Damian Peach: The Atmosphere and Observing, which describes some of the factors that influence "local" seeing.

He has some other articles on his site related to seeing, predicting the seeing, jetstream etc.

Some good reading!

[Blue Skies (Jacquie)]

Places to avoid: large areas of nice heat collecting rocks that radiate all that heat back into the air at night, looking over a roof or lots of roofs, looking over a multi-lane highway, setting up on bitumen...

Other bad spots can be low down or in a hollow, because that is where cold air collects and you'll get dewed out much quicker than if you're on the higher end of a slope.

To me local seeing is all about the air over your head and that is largely controlled by the weather, so just being familiar with the local weather patterns and effects it might cause would be good. I'd also want to avoid a place that gets very windy - perhaps you're in a mountain area that gets descending winds or a valley that funnels the wind.

[okiscopey (Mike)]

Thanks Mike and Blue Skies - I now have a better idea of what that was all about!

[ballaratdragons (Ken)]

I just read the article by Damian Peach in the link Mike provided.

Yep, I agree that foggy nights are fantastic!!!!!

Here at Snake Valley (altitude: 490m) the seeing is amazing on a foggy night! And fortunately, the fog doesn't last long. It fogs up almost instantly like someone turned the fog switch on. When that happens, I go inside and make a cup of coffee. Come back out, fiddle with a few accessories or read Cartes du Ciel etc, and usually within the hour the fog settles down to ground level and the sky is absolutely magic!!!

Another bonus is that the fog collects any airborn particles in the lower atmosphere and drag them down to the ground as it falls.

So not only is the air calm and the seeing great, but the air is cleaner too