[Shop-talk] Run air tools on a water hose?

[Jeff Scarbrough]

On Mon, Aug 15, 2011 at 11:46 AM, Scott Hall
<scott.hall.personal at gmail.com> wrote:
> Hm...are you sure about that?  It's been a long time since my earth science
> classes, but I seem to remember that as the air heats up, it'll hold more
> water.

Yep.  In general.

> So if there was a fixed amount of water available, your explanation
> would be correct.  Since there isn't, as it gets hotter. the air would hold
> more water.

Well, that depends.  In many (most?) places, there isn't a ready
supply of moisture to be taken up by the atmosphere, beyond plant
respiration or something like that.

> This seems to play out here (where we make Georgia look like
> the cool Patagonian desert), where the humidity stays fairly constant
> according to our humidistats throughout the day (or year, even) even as it
> clears 100 degrees F.

Depends on where "here" is.  If you live next to a large body of
water, then yes, that's possibly the case.  But what happens to all
that water as the air cools?  Must be like a rain forest.  I just bet
it feels "oppressive and sticky.  And then some.

Anyway, I was just generally trying to describe the difference between
Relative Humidity, which is, well, relative, and moisture content of
the air as a volume/volume relation; and thus why running the
compressor in the morning vs. afternoon might not make much
difference.

Jeff Scarbrough
Atmospheric Physics Acres, Ga.