"OzWineKitz" > wrote in message
om...
> Does anyone know the relationship between Hydrometer Accuracy and
> Barometric Pressure?
>
> That is, what is the inaccuracy of a Hydrometer with variations in
> atmospheric pressure?

I'm sure that hydrometer readings are for all practical purposes essentially
independent of atmospheric pressure. Of course you could argue that at
increased pressure the glass envelope will be smaller, yielding lower S.G.
measurements, but I defy you to measure the difference across the normal
range of barometric pressure!

Altitude is another matter however, as the effect of gravity diminishes at
higher altitudes. In space, e.g., the hydrometer would float out of the
jar. For that matter, so would the wine.

Temperature also affects S.G. readings. My hydrometer indicates that its
readings are for liquids at 60°F, and a correction chart is included for
other temperatures.

Tom S