[SteveBz]

I know this is an old topic, but it gets more important every year. I think that should be the other way round. More water vapour, less room for co2.

Here's the calculation:

Calculation

Here's how they do it at Mauna Loa:
CO2 Measurements


They have RH in the scd30, it could be done automatically, but I see no reference to it.

Kind regards,

Steve