The ASOS instruments used by the NWS include a chilled mirror device to
measure the dew point. Those are quite expensive. Cheaper installations
use humidity sensors. Examples of those are ones that use a fiber,
measuring torsion changes, or hygroscopic substrate, measuring
conductivity. The latter, in my opinion, tend to degrade quickly with
pollution aerosols.
Jim
Gene Mechtly wrote:
>
> On Mon, 16 Jul 2001, Bill Potts wrote:
> > ...
> > I think the following are correct:
> > ...
> > no unit for humidity, just %
> > ...
>
> Humidity might be measured by the "due point"; the temperature of a
> polished metal surface onto which water precipitates from (still) air.
> No precipitation at higher temperatures. Much condensation at lower T.
--
Metric Methods(SM) "Don't be late to metricate!"
James R. Frysinger, CAMS http://www.metricmethods.com/
10 Captiva Row e-mail: [EMAIL PROTECTED]
Charleston, SC 29407 phone/FAX: 843.225.6789
