effects of lakes and rivers on seeing?

[captcha]

I'm close to some lakes and rivers and have always wondered what effects these large bodies of waters have on the seeing. Will the air above these water be more humid because the waters lag in cooling down down once the sun sets? If true, does that mean it will negatively affect seeing when observing at low elevations?

[Saturnine]

Hi and welcome to the forums.
Seems that no one else is replying to your question so thought I'd say something. From my understanding, observing near large bodies of water helps to steady the "seeing" because such bodies of water don't heat up as much as the land during the day and don't cool as much at night. The decrease in temperature variation of the water compared to the land means less temperature induced heat plumes over the water, hence steadier seeing. Humidity is less a factor in determining the seeing conditions than temperature differences.

[Dave882]

I think in general the seeing over a body of water would certainly be better than over hard surfaces. However if there is a mist or fog forming over the water in certain conditions that could really be a problem.
Some of the best seeing for planetary photography is due to large bodies of water producing laminar air flow, however it’s normally an ocean rather than a lake/river.
Best way to find out regarding a specific spot is to give it a go. Remember that things can be very different summer vs winter.

As a side note, a lake/estuary full of mozzies is absolutely zero fun.

[captcha]

I'm fairly new to astrophotography and probably wouldn't be able to tell the difference between good and excellent seeing, but I have been curious about what the effects would be.

Last December I took some images of comet Leonard and it was about 10 degrees above the horizon in the West. I set myself up about 1 km from the Hunter river, just north of Newcastle and I really didn't know if the water or content in the air was going to spoil or improve things. Nearby Grahamstown dam is a much larger body of water and I was wondering if I could use that to my advantage or stay as far away from as possible.

Temperature fluctuations makes sense. I think that's more pronounced over hard terrain so all in agreeance there. Just wanted to reach out here to see if I missed anything obvious.

Mozzies are the worst.. hehe..

[Startrek]

My Obs on the South Coast of NSW is located 150m from the beach. I’ve been observing and imaging there since 2016
The ocean, a large body of water can be your friend and foe
When the northeasters blow in summer and back off at night , seeing is generally poor to average due to salt mist in the air and humidity etc..
In Winter when light south westerlies blow at night , seeing is generally good as air is dryer and humidity is generally lower
In the Spring we do sometimes get sea fog or sea mist rolling in late evening/ early morning which affects seeing
Imaging and Observing over a large body of water like the South Pacific in theory is a good scenario for astronomers but not always the case in reality

At the end of the day , the ever changing cycle of weather ( Mother Nature) , particularly along our eastern seaboard of NSW is a moving target so it’s rare to get say 3 or 5 nights straight of good to excellent seeing and transparency.

When there’s no cloud around most of us take what ever is dished up and make the most of it

Cheers
Martin

[captcha]

Thanks for sharing your practical experiences. I appreciate that.

And thanks for the welcome. Yes, first time posts here. I hope to get a bit more into ap later this year and finally get a setup that is a bit more than just parts hobbled together, haha.

One more question regarding seeing, and I think I can guess this, but is the air generally better in winter than in summer? I have the idea that humidity is less in winter so that should be the better season to benefit from good seeing?

[Startrek]

Winter or Summer ?
Depends where you live ?
How long is a piece of string ?
I’ve had great nights during both Summer and Winter
Like I mentioned, if it’s clear get out amongst the stars and find out , you will eventually learn from experience conditions at your observing or imaging location.
Cheers
M

[Max Vondel]

Yeah I think it depends a lot on location. And annual variations.
Nothing is perfect. Colder temperatures are better for all our sensors but numb fingers are not. Moisture levels can behave strangely. Sometimes stars fade as the moisture condenses out and you hardly notice. From dry to wet in 10 minutes But it can add some lovely coloured haloes around wide angled star shots for nice effects as a positive.