[Weather] Acoustic rain gauge

[Dave Flory]

For what it is worth, when doing calculations of drop growth via 
collision/coalescense (where it is vital to know the relative speed 
between the collector drop and the drops being collected), drop terminal 
fall speed is typically taken to be directly proportional to the drop 
radius, or v starting point.


On Thu, 26 Apr 2007, Frédéric wrote:

> Le jeudi 26 avril 2007 12:55, Matthew Smith a écrit :
> 
> > Measurement of rainfall by this means is not - as far as I can see -
> > feasible.  Rainfall is about volume (per area); an acoustic transducer
> > could only really measure the product of the velocity of an incoming
> > drop multiplied by its mass (will the real physics guys help me out
> > here?)  These "hits" would not contain the data to measure the
> > volume/area.
> 
> Tell me if I am wrong, but because of the air, and because a drop is not 
> solid, its speed only depends on its mass, no? I mean, falling from 100m or 
> 1000m, it will reach the same speed (if a physician could confirm...) So, 
> measuring the energy of the sound can give its mass, so its volume.
> 
> Air temperature and pressure are parameters to take into account... ut if 
> there is wind, the drop will not produce the same sound, as it will not hit 
> the surface with the same angle.
> 
> Not very easy, so :o/
> 
> 

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