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Re: (meteorobs) Humidity
Robert/All,
The humidity at ground level varies drastically with elevation. A better
way is to log onto a weather website that displays the RAWINSONDE data
collected by weather balloons twice a day around the globe, at 00 and 1200
hours UTC from many locations. My favorite location from San Diego,
California USA is:
http://meteora.ucsddot edu/weather/cdf/images/myf_skewt.gif
that displays data through the atmosphere which tells the humidity,
temperature, and windspeed/direction versus altitude. The graphs are a
little difficult to learn how to read, but overall the LM and visibility
depend on <all> the layers in the atmosphere, not just ground level
readings. A good websearch would include "skewt" or "RAWINSONDE" to find
other locations.
Clear Skies,
Jim jfoster@adnc.com
Eastern San Diego County, Southern California, USA
32 deg 41.346 N
116 deg 45.357 W
2188 ft. elevation
Robert Gardner wrote:
> I know that Robert Lunsford takes the humidity at his observing site at
> some time during his observing. Maybe others do too. I was wondering
> if anyone has ever checked for a correlation between LM and humidity.
> The simplest way to do this would be to make a point graph of LM verses
> Humidity. Or you can mathematical using regression analysis (least
> square fitting to curves). The reason I ask is if there is no
> precipitation in the form of ice crystal, snow, rain, clouds or fog, I
> see no pro or con for this. It may surprise some people that moist air
> is lighter than dry air. However since the same density of molecules
> are involved in any case you might not think there would be any
> correlation. What brought this to mind was Mike Linnolt mentioning that
> the humidity was low at one of his sights. You might also wish to take
> into account altitude, or atmospheric pressure if you have that data.
> I'm assuming that atmospheric pressure is a measure of the air mass.
> This would require a way to graph in three dimensions or the
> mathematical approach.
>
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