Melbourne Weather Conditions Theory

[Stonius]

Hey all,


I live in an apartment so getting out under the stars requires travel and setup, even if it's only to the park down the road, so it would be good to optimise my viewing opportunities by getting a handle optimal weather conditions. And I figure if I'm in the car anyway, now lockdown has ended, I could do a lot better than an inner city park surrounded by miles of houses.



Now if I'm after dark skies, that's pretty simple; get out of the city. But if I'm looking for good seeing, that would seem to imply different demands from an observing site.


Given that absolute darkness is not necessary for planetary work, I could possibly find a spot a lot closer than the ASV site up at Heathcote.


So these are the thoughts I've been having.



Looking across tarmac and rooftops is bad, so viewing planets that are kind of north-ish in the sky, from *south of the city is probably not the best; Get out of suburbia which for me means heading out Geelong way.
Laminar Airflow is important for seeing. Ideally you want a sheet of air coming at you that has not had to wind its way over obstacles or bodies that are radiating heat. An onshore breeze is good as the air is coming in off the flat ocean - but you don't want to be *at the shore because of the salt in the air (bad for optics). This means a gentle southerly breeze is best, when viewed across a flat plain a little way inland.
Any land mass is going to re-radiate heat at night. if you can get above that 'boundary layer' of turbulence, you'll have better seeing; Find a hillside that faces south.
Jetstream. it moves around a lot, but do southerlies help shift it up to more northerly latitudes so we can peek out underneath it?

So based on the above, I'm thinking a hillside somewhere out near the You-Yangs might work. Am I crazy? Well yes I am, thanks for asking - but am I crazy in this particular aspect?



Cheers


Markus

[mura_gadi]

Day time surveillance of the site is very important imo.

If you're checking for height, main thing to look for imo, is does the hill pop up from the dust/pollution layer that is your valley... Its a lot easier a few hours either side of dawn/dust to see where the dust/pollution/pollen lies around the surrounding area.

Checking for young people paraphernalia around the site...

Your suggested site is a MTB area, do they ride much at night?

Other option:
Do you have any cricket nets close by? If the area is reasonably safe after dark, a few pegs and used blankets make a quick light protected end.

The oval will lose heat quickly and hopefully get a reasonable open area of the sky.


One to remember - Never go into a pollinating pine plantation...

[Nikolas]

Head to the mornington peninsula or the bellarine closer than heathcote

[etill]

I had planned to try down around Cape Shank in some of the beach car parks at some stage. We have a house on the peninsula so it is close enough to not have to drive too far. I noticed on some light pollution maps that it seemed like it had fairly dark skies looking to the south away from Melbourne.

[etill]

What Nikolas said..

The concern I had (and still do) is some of those areas are parks and may be closed or off limits at night in some areas.

[Stonius]

Absoloutely - planning to take a little drive to checkout the various sites I found.




I could just pop down the road to como park. its dark and secluded with no bright lights, but I'm looking north across millions of houses. even though the closest houses are probably 500m away I figure that would probably make a difference?


What's MTB? The You-Yangs are closed at night, so I can't go there, but I was thinking maybe somewhere down that way.


Cheers


Markus

[Stonius]

Are they though? I don't think so for me (South Yarra). But are you saying the atmosphere is more stable down that way with ocean air rather than air that has come all that way over land?





Yes, it requires some scouting to make sure. Google Earth only gets you so far, but it is incredibly useful.



Cheers


Markus

[mura_gadi]

MTB - Mountain/Trail bike riding area...

Some National parks are often free, open 24 hours and provide some great viewing places. Give the rangers a ring at Brisbane Rangers National Park and see how helpful they are.

The ones in Canberra I have talked to have been great once you explain what you want to do. They might offer a few places to try straight up.

They have shooters operating at this moment so its a no go for a little while.
*Make sure the park is normally off limits to hunters... a real biggie! (Lerderderg State Park is around the same travel distance, State parks can allow hunters, National Parks are restricted...)

[Stonius]

Has anyone noticed any seeing trends based on wind direction?


By way of example, I notice meteoblue is predicting 0.5 arcsec seeing for most of the daylight hours tomorrow. And a southerly wind again. 100% cloud though, so don't get too excited - and that's still with a jetstream running at a fairly moderate 60 knots.


Markus

[Stonius]

Ah, yes, hunters - good point! Yikes!

[Lariliss]

Your approach is meaningful.
We are bored with 'light pollution' and 'light pollution map' sentences.

Good example of how it works in reality for a particular place.
If you can check it against the Bortle scale (https://en.wikipedia.org/wiki/Bortle_scale), it will tell what is right what is wrong.
Places are scaled for permanent features, but you are doing for more volatile ones.
If that volatile classification could go further one may evaluate 'good' and 'not so good' star gazing times in their locations.

[mura_gadi]

I'll be accused of being a parrot shortly on this one...

earth.nullschool.net >
Mode = Particulates
Animate = Wind
Overlay = DUex (PM10 etc)


https://earth.nullschool.net/#current/particulates/surface/level/overlay=duexttau/orthographic=-210.31,-34.80,3373


That's the only source file I know to track airborne particulates with a live feed. Hopefully there are others and people will chime in.

(One time... I dropped the mirror cell off the back of the scope while still learning things. Part of the whole recollimation sage, was I got to see the airbourne moisture packs, they're actually pretty cool to look at. Kinda like a two tailed sperm, with one tail going up from the water pack and one going down from the water packet, but not touching the packet, more like mist trails... I spent a bit of time looking at them as it turned out, was very interesting watching them) .

[Andy01]

Cricket season is about to begin again and Como has lights on the oval for training. Also be careful of 'landmines' underfoot, as there are a zillion dog walkers there!

I'm a life member of the South Yarra Cricket Club and we named one end of the pitch the Dog Sh#t end for that reason! :lol:

[Stonius]

Giving away my secrets here, but I'm talking more about Como Park North, the elevated oval. It's quite secluded for inner city, and has no direct light sources. I haven't even been stabbed there yet! Of course, next time I go it's going to be full of a million telescopes! :-D

[xelasnave]

Cant you bribe the building manager to let you have access to the roof of the building you live in?
Alex

[Stonius]

We have a roof, but it's all just colourbond and gutters I'm afraid. No access unless you're good at climbing. Missed opportunity if you ask me.


Markus

[mura_gadi]

" I haven't even been stabbed there yet! "

With an attitude like that I am sure you'll find somewhere...

I notice no-one has commented on the roof thing, I would guess, if you more than 500m away and viewing above 45degree with a slight wind you'd be fine.

Unless the day was a scorcher, heat from the roofs by astro dark should be manageable from that distance... Big shopping centers or large carparks maybe not.

I have edge of suburbia inside a golf course, so our heat is reduced and fades quicker.

[Stonius]

Yeah, it's hard to know, not being versed in the dark arts of meteorology.

I know that cumulus clouds are due to thermals rising from the land, so who knows how high thermals from rooftops go amd how disruptive they are?

[mura_gadi]

Desert go close to zero or below every night due to no vegetation trapping heat. So grass fields etc are way better than mature trees to looks over...

I'd say jump on your own roof and see when it cools down as the easiest, but I'm thinking single dwelling block, so, maybe just use the tarmac on the road. If it feels cool to the hand, heats is probably "going to gone" from the roofs as well.

Another thought is since Covid we are now charging for camping grounds ($6) and you need to book. The one advantage of this is you can check the camping grounds late in the day to see if they have any bookings that night.

At least you can find a site to yourself that shouldn't have any others users that night. Some camping grounds are little more than clearings though.

The ones I checked around Canberra were, if I wasn't throwing a tent or making a fire, I wasn't camping and I just had to let them know and they'd check the books.

[Tulloch]

I image from my tiny backyard in Bentleigh East, good view north but surrounded by houses. The best images I've got of the planets are when I'm not looking over the city (ie west), but right now the planets are basically overhead at dusk.

One of the key aspects is to cool your scope down to ambient temperature, which takes an hour or two if you don't have cooling. Then, it's up to the weather gods to decide if you get good seeing. Remember, seeing changes frequently, minute by minute, all you need is a lucky 3 minutes! If you can see 'em, then you can image 'em :)

Do you have a balcony? Here's what someone was able to produce from his balcony in (light polluted) Paris.
https://www.cloudynights.com/topic/794644-global-map-of-jupiter-done-from-my-balcony-in-paris/

Check out this video for his location and final result
https://www.youtube.com/watch?v=nbA1HVVDgwA

Andrew