[time-nuts] Re: Dense pressure data of the last 24h and the next 48h

[Lux, Jim]

On 1/19/22 3:50 PM, Hal Murray wrote:
> anders.e.e.wallin at gmail.com said:
>> AFAIK we only have 10 minute data...
> What is the wavelength (in seconds) of an eruption?  What's the Nyquist
> sampling rate?

 From the shock wave?  I'm not sure wavelength is the appropriate 
measure - a shock wave starts as a step function, and then eventually 
relaxes to some sort of slope.



> Is there dispersion of audio signals in the atmosphere?  I don't remember
> hearing about it.  Maybe signals going around-the-world are different due to
> interactions with the ground or open top,

Yes, there is dispersion - not in the variation of speed with frequency, 
but the atmosphere has different temperatures at different heights, so 
that causes dispersion, as do surface winds.


>
> ----------
>
> What sort of sampling rates do metrologists want or get?
>
> ----------
>
> What sort of gear do people use if they want to be able to see this sort of
> thing?
>
> What is the noise like?  Is it mostly from wind?  How many bits of signal are
> left on a windy day?  Or what should I be asking?
>
>