Weather factors for good viewing

[roberte76]

Is the atmosphere too complex to predict good viewing or are there factors that help us to know that viewing will be good ahead of the nights viewing?..... eg ; I sometimes think a slight breeze is better than a still evening in winter when mist seems to gather more easily.

your thoughts would be appreciated

rob

[Talitha]

Hi Rob, here in the States I check to see what the Jet Stream is doing. It seems to enjoy whipping back and forth over the Great Lakes region where I live, and when it's passing overhead the seeing is jigglymush. (My state [Wisconsin] is just to the left of Lake Michigan.. the long skinny vertical one.)

[GazOC]

I don't know about predicting it but I find after rain and before fog can often give good seeing.

[roberte76]

Thanks both of you ,I find that a slight breeze in cold weather tends to stop mist from forming hence aiding viewing, the jet stream .....very interesting

I read somewhere that here in England easterly winds are drier than westerlies and therefore are better for viewing?

[TheThing]

jigglymush.

Obviously a technical term! That gets my vote as word of the week, squeezing equidistant into second place.

I've heard that air over water can be better as well, hence the ideal observatory would be on a tiny island in the middle of a lake (doubly good after rain!). Near the sea is supposed to be good too. Isn't there a famous astonomer who lives near the sea at Selsey? Might just be co-incidence!

[Doc]

I put the word "jigglymush" into google and there was 3960 instances of that word.

Great word.....

[TheThing]

Wow! A lot seem to refer to cellulite!

[roberte76]

OK so damp air is better than dry air?

[lunator]

Hi Robert

This is an area where a lot of confusion happens. There are 2 key components on the effect of viewing.

Seeing - This is the atmospshere's steadiness

Transparancy - This is how clear and dark the sky is.

My experience is as follows.

Generally in the UK you trade seeing and transparancy. The best nights for seeing when the atmosphere is quote still allow mist to form and this makes the transparency poor. This usually happens when a High pressure is over the UK.

If the High pressure has drawn air up from the South it will be fairly high in the amount of water it contains and as it cools this will turn into the mist/fog.

On nights when the seeing is poor the transparency is generally better as this is when we have had a weather front move through. The rain clears out the 'muck' in the atmosphere and this reduces the amount of LP that gets bounced about.

As the air is moving through it doesn't tend to let the mist form.

There is an exception to this rule.

If a high pressure system has formed in the Arctic and moves down over the UK or a weather front has drawn down the air from the arctic. The air is dry and cold. This creates a situation where the air is quite still so seing is good but as it is also very cold it has a very low water so the transparency remains good.

I hope this is clear

Cheers

Ian

[Vega]

Great.... bring on the arctic high's then

Very interesting and informative explanation, cheers Ian

Matt

[almach]

Thanks for the explanation Ian. I've just given up as both the seeing and transparency are appalling i.e. it's bobbins with a high jigglymush factor

cheers

andy

[Keithp]

I agree with Ian, took me 2 months just wait for Saturn...complete nubie tho'

Patients, pacience or what ever is the virtue of something or other...

Regards

all

KP

[roberte76]

thanks ian thats the sort of info i was looking for

rob