How to predict visibility?

[Alf]

Hello,

I understand that visibility, particularly long range one, is influenced (from my limited understanding) by temperature, air humidity and suspended particles.

I'd like to know how could I get an idea, even a rough guess, of how far could I see (both unaided or with a telescope) on land until visibility itself (and not my optics) becomes a limiting factor, before getting out in the field and measuring it by myself with known landmarks (other mountains, cities, etc.).

Overall I'd even be happy to be able to have hints on setting apart days with 50 km visibility from those with 100 km or better visibility.

Thank you

Alfred