Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Poor seeing conditions in an otherwise clear sky - predictable?

  • Please log in to reply
11 replies to this topic

#1 AstroCub

AstroCub

    Sputnik

  • -----
  • topic starter
  • Posts: 37
  • Joined: 04 Jul 2020

Posted 01 October 2020 - 08:27 AM

Hi,

 

We had our first clear sky here (Virginia USA) in quite a while so I spent the day excitedly preparing Celeste & Cubble for viewing.

 

However, when it came to viewing, the conditions were shockingly bad. Stars looked like squirming fuzzy snowballs and I could not achieve any kind of focus on Jupiter in anything more powerful than a 25mm eyepiece. It was so bad I was sure there was something wrong with Cubble but Celeste was suffering the same problems.

 

Anyway, my question is, is it possible to in any way predict these bad viewing / seeing conditions even when the sky appears cloudless? 

The wind was a gentle SW and we had high pressure for at least 18 hours preceeding the evening. 

 

We have had issues the last few weeks with extreme high altitude remnants of smoke from the California wild fires but I'm not sure these were to blame last night. The images I was getting weren't smudges or fuzzy but more like looking at the objects submerged underwater.

 

So any factors that we can watch out for that might contribute to poor seeing in a cloudless sky??

 

Thanks!!!

 

Siouxsie 



#2 Chris Johnson

Chris Johnson

    Ranger 4

  • *****
  • Posts: 356
  • Joined: 08 Sep 2004
  • Loc: Stockholm, NJ

Posted 01 October 2020 - 08:54 AM

The jet stream was howling overhead last night up until 4am when I went inside. If the stars are twinkling with the naked eye the seeing will be poor at best. Check out the web site “Astrospheric” for the Astro forecast.


Edited by Chris Johnson, 01 October 2020 - 08:56 AM.

  • Frugal Astronomer likes this

#3 csrlice12

csrlice12

    ISS

  • *****
  • Posts: 26,920
  • Joined: 22 May 2012
  • Loc: Denver, CO

Posted 01 October 2020 - 10:21 AM

Welcome to the wonderful world of astronomy!  As time goes on, you will find you get better at weather forecasting then the TV weatherperson.  You will also find it expands your vocabulary....but every once in awhile the only word you will need is silence as your jaw drops to the ground (please try to keep it closed though as hot breath can interfere with viewing too).



#4 tommm

tommm

    Viking 1

  • *****
  • Posts: 852
  • Joined: 16 Dec 2015

Posted 01 October 2020 - 11:22 AM

Are you familiar with the Clear Sky Charts at Clear Dark Sky? They are usually fairly accurate on predicting condition a night or two in advance. And yes, twinkling stars are a sign of atmospheric turbulence resulting in only fair to poor seeing.


  • stevew likes this

#5 Frugal Astronomer

Frugal Astronomer

    Sputnik

  • -----
  • Posts: 33
  • Joined: 16 May 2020
  • Loc: Philadelphia area

Posted 01 October 2020 - 11:32 AM

Another vote for Astrospheric.com.  For my location, I find it to be more accurate than the local Clear Dark Sky chart.  In this area, seeing has been generally poor for several weeks, despite some nice clear skies.



#6 clearwaterdave

clearwaterdave

    Fly Me to the Moon

  • *****
  • Posts: 5,219
  • Joined: 27 May 2014
  • Loc: Western Maine

Posted 07 October 2020 - 07:07 PM

Hello.,If your temps are changing a lot.,Like nice 65* day down to a 38* night,.this will give the air that "hot asphalt" ripple which will show when you try to power up.,Along with an active jetstream things can get ugly even on a nice clear night.,These nights are best used for low power stuffs as you found out.,good luck.,



#7 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 87,238
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 07 October 2020 - 09:20 PM

I am liking https://www.goodtostargaze.com/

 

So far, it seems pretty accurate on the seeing.  

 

Jon


  • Elroy likes this

#8 NYJohn S

NYJohn S

    Vanguard

  • *****
  • Posts: 2,392
  • Joined: 14 Feb 2016
  • Loc: Northport, NY

Posted 08 October 2020 - 04:07 PM

I’m another Astrospheric user. I have a night like that forecasted for tonight. Poor seeing but above average transparency. I won’t be looking at planets even with Mars near opposition. Instead I’ll shift to galaxies and other dso. That seems to happen quite often here. A front comes through and clears the sky but the seeing is poor until things settle down.

#9 Ittaku

Ittaku

    Ranger 4

  • -----
  • Posts: 337
  • Joined: 09 Aug 2020
  • Loc: Melbourne, Australia

Posted 08 October 2020 - 04:36 PM

A prediction's only a prediction and the further you are from the actual time, the less accurate it gets, so keep a watch of them until the actual time, and ultimately check for yourself. Another site worth visiting with plenty of information - try meteoblue, click on outdoor and sports along the left and choose Astronomical seeing.

 

https://www.meteoblue.com


  • Jon Isaacs likes this

#10 Migwan

Migwan

    Vanguard

  • *****
  • Posts: 2,121
  • Joined: 24 Jul 2017
  • Loc: Meeechigan

Posted 08 October 2020 - 04:43 PM

For my area, seeing is never set in stone.  I look at Clear Skies, Jetstream and lately, GOES East.

 

Regarding GOES East, I've been been looking at the difference in temperatures between Bands 8 and 9 and again between 9 and 10.  If there's a large difference in either, then seeing is probably not going to be so good.  I've only been keeping an eye on this for a few months now, but so far it seems fairly predictive.   These are IR bands and relate to humidity and can help when considering transparency also, though the temps expected for good transparency change seasonally and seem to relate to ground temperatures at the time.  

 

jd



#11 Andrew Brown

Andrew Brown

    Mariner 2

  • -----
  • Posts: 239
  • Joined: 18 May 2020
  • Loc: 56.4451° N, 3.1670° W

Posted 09 October 2020 - 06:41 AM

The jet stream was howling overhead last night up until 4am when I went inside. If the stars are twinkling with the naked eye the seeing will be poor at best. Check out the web site “Astrospheric” for the Astro forecast.

Well that's crapolla.



#12 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 47,690
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 10 October 2020 - 02:24 PM

Hi,

 

We had our first clear sky here (Virginia USA) in quite a while so I spent the day excitedly preparing Celeste & Cubble for viewing.

 

However, when it came to viewing, the conditions were shockingly bad. Stars looked like squirming fuzzy snowballs and I could not achieve any kind of focus on Jupiter in anything more powerful than a 25mm eyepiece. It was so bad I was sure there was something wrong with Cubble but Celeste was suffering the same problems.

 

Anyway, my question is, is it possible to in any way predict these bad viewing / seeing conditions even when the sky appears cloudless? 

The wind was a gentle SW and we had high pressure for at least 18 hours preceding the evening. 

 

We have had issues the last few weeks with extreme high altitude remnants of smoke from the California wild fires but I'm not sure these were to blame last night. The images I was getting weren't smudges or fuzzy but more like looking at the objects submerged underwater.

 

So any factors that we can watch out for that might contribute to poor seeing in a cloudless sky??

 

Thanks!!!

 

Siouxsie 

Yes, you can use the weather maps to predict seeing.

Read these few articles written by a weatherman-astronomer:

http://www.cloudynig...observing-r1396

http://www.cloudynig...udy-night-r1413
http://www.cloudynig...observing-r1436




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics