Generaly speaking, when is best viewing?

[CR500 (Rod)]

I finaly got my 6mm eyepiece today as well as my 2.5x powermate to use with my other EPs. Only problem is, when looking at Jupiter, it was nice and bright, but not very clear at higher powers.
Today was 37 degrees and had a dusty haze in my area, so no doubt this had some effect. When is viewing usualy best? Cool nights, windy nights, after rain, when the air is dry???

[doppler (Rick)]

Hot nights are the worst especially if there are buildings nearby, if you look at something bright like the moon you can see the heat waves shimering. Cooler nights are best and after rain any dust is usually cleared from the air as well. Too cold and telescopes start fogging up.

Rick

[barx1963 (Malcolm)]

As a rule colder is better. Air tends to be stiller at night and less insects. You quickly learn to appreciate dew heaters and warm clothing though!

Given all that, seeing can be rubbish on some cold night and lovely on some warm nights, it just depends as most of the seeing effect happen high up not down at ground level.

Malcolm

[Varangian (John)]

I've had my very best views of Jupiter after midnight when things settle down. I've also heard on CN that humid conditions, not hot, dry conditions provide better seeing. This may well be a furphy.

[Satchmo]

Sunset in Spring and Autumn, and after midnight generally.

[ausastronomer (John Bambury)]

It also has a lot to do with your local topography as well as the prevailing weather conditions. If you are at sea level near the sea with nearby mountain ranges/escarpments you will often experience poor seeing, due to the turbulence created by the escarpments. Just ask Rod Berry (Rodstar) how often he gets sub arc second seeing at his house at Point Clare with the mountains of Brisbane Water National park right behind him. Answer = NEVER.

Cheers,
John B

[Wavytone]

As mark suggested, spring and autumn - and around 2-4am when wind strength is usually at its minimum.

Local terrain counts for a lot too, with respect to micro-climate, and an understanding of how the wind changes direction between day and night.

Fior example, if you live near cliffs that catch the afternoon sun they will warm and produce thermals all evening that degrade the seeing above. Thermals also drift downwind and if the prevailing evening airflow blows the thermals over your site, poor seeing will affect you for most of the sky, till the rocks cool down (early morning).

Another influence is the type of terrain around your site. For example farming country or suburban areas with extensive gardens, grassed parks or sports fields mean dark soils which absorb lots of heat during daytime and then release it at night causing thermals and poor seeing, as well as moisture (as they are watered). So expect fogs and frosts if inland. Conversely light sandy soils or sandstone terrain (even better) don't build up so much heat (less thermals) and drain very freely, so fog or frost in these areas are minimal and the seeing will be better.

As for fog, even if it dies firm on a plateau, it is more dense than dry air so it tends to flow downhill. Hence better to be on a ridge than a flat location.

[2stroke (Jay)]

A real easy way is if you see the stars twinkling then don't bother imaging lol. What scope and f ration are you using? 6mm and a 2.5x your probably pushing the optics way past spec anyhow.