Let's say that plant X is reputed to thrive nicely in a highly
humid environment. First, I assume that we're talking about RELATIVW
humidity. Let's say that plant X likes 90% relative humidity (RH) and
above. Does this mean that plant X will be just as happy with 90% RH
on a 95 F day, as with 90% RH on a 80 F day?
To most long time growers, this might seem like an obvious
question and I'm sorry about that. I'm never satisfied with following
simple instructions--I like to know the hows and the whys.
For 90% RH, there is less water vapor in a volume of air at
80 F than in the same volume of air at 95 F. Do humidity sensitive
plants care? Are they more sensitive to the actual amount of water
vapor present, that is, the absolute humidity? If we consider the
extreme case of 90% RH on a 35 F day, we find that the air is still
pretty dry relative to 90% RH on a 95 F day. Of course this is moot,
since most plants that like high humidity also need warmer temperatures.
It is useful to look at extreme cases to understand the physics of
what's going on. (By the way, I'm assuming the same air pressure in
all cases where I speak of volumes of air.)
Any comments? I'm a scientist by training, and I know these
discussions can get pretty heavy into physics as well as plant biology.
Go ahead, make my day. And, thanks.
Perry