Transparency and seeing

[The Warthog]

How is transparency measured, officially? "The transparency's like poo tonight" is a trifle subjective. So, how do you communicate transparency in a way that is meaningful to other observers?

Similarly, is there a measure for seeing?

[GazOC]

The Antoniadi scale for measuring seeing

1 perfect seeing,

2 slight undulations

3 moderate seeing

4 poor seeing

5 very bad seeing

Theres also the Pickering scale which is the same idea but (10-1 ie the other "away around")

Transparency is measured in NELM - Naked Eye Limiting Magnitude (at zenith) which is self explanatory.

[The Warthog]

Thanks! I'd say seeing has been about 1.5 or 1 over the weekend.

I'd have to add 1 to any estimate of NELM with my eyes. Everyone else seems to be able to see stuff I can't. Unless they're just gaslighting me.