[time-nuts] Cavity frequency air filled vs vacuum?

[Jim Lux]

On 8/18/15 10:30 PM, Bruce Griffiths wrote:
> The ratio of the resonant frequency of the evacuated cavity to that
> of the air filled cavity increases by the square root of the relative
> permittivity of the ambient air or around 300ppm or so. Bruce
>
>



I believe that there are systems that measure humidity by this means. 
Water content has a strong effect on permittivity.  Although, since 
there's just not that much water in humid air, it's probably in the few 
ppm range, but easily measureable