[CAUT] FW: Temperature/Humidity range

[Fred Sturm]

On 1/18/06 9:40 AM, "Chris Solliday" <solliday@ptd.net> wrote:

> I'd like to revise my last reply to Alan, I'll stick with "will" because
> here when the temperature rises around here in summer the humidity does
> also. This does imply a rise in water vapor. I realize this is not what you
> are addressing but it is what I was saying. I'll will try and be clearer
> from herer. Nevertheless the site
> http://ianrpubs.unl.edu/generalag/g828.htm#pc is very helpful and whether we
> are concerned with pigpens or concert halls I think the info is well
> presented. Chris Solliday

    It is true enough in certain climates (NE and midwest, for instance),
that higher temps usually mean higher humidity, but this is not at all
absolute. Partly that syndrome is the result of fairly extreme outdoor
temperatures. When they are very low in the winter, much of the water vapor
is removed from the air because cold air won't hold much. When that air
(which, BTW, has a very low dew point) comes inside a building and is
heated, the RH is going to be very low (unless moisture is added), probably
much lower than summer.
    But climates may vary and cause the opposite to occur. Here in New
Mexico, we do usually get a humid period in the late summer (July/August),
due to seasonal afternoon showers. But before those arrive, in May and June,
we can often have our very driest conditions, at very high temps (90 - 100F
being common then). I have measured below 2% outside in June during one of
our recent drought years. And there are places like, I believe, parts of
southern California, where the summers are dry, and the winters are the
rainy season.
    IOW, it ain't all that simple. Though it may be in PA <g>.
Regards,
Fred Sturm
University of New Mexico