OK, Peter. You're going to have to help me with this one:

You stated "Humid air is lighter than dry air". How can that be? Humid air
is dry air containing water vapor, so how can (stating it mathematically)
X + Y X ?

In reality, the heavier, humid air will stay settled around the plants until
diffusion or forced dispersion moves it away.

You're right: humidity trays may not help much, or at all, but they do
protect the furniture!

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!
..
"Peter Aitken" wrote in message
news
"Ray" wrote in message
...
I cannot argue with your evidence, but I stand by my general comment.
There
are too many factors involved - air flow from fans, heaters, etc., how
well
sealed the room is, and those inconsequential laws of nature.

Nature always wants an equilibrium, i.e., no gradients. A single source
of
evaporation will raise the humidity in the immediate area, but those
airborne water molecules will quickly disperse into the entire room, and
if
that room is not sealed off from the rest of the house, into that full
volume as well - and beyond. The simple fact that household humidity is
low
in the winter proves that the moisture emanating from showers, sinks,
dishwashers, washing machines, our own perspiration and exhaling, etc.,
is
diffusing out into the dry environment outdoors.

If the %RH near your plants is 10%-15% higher than the surrounding room,
I'd
speculate that you don't have sufficient air movement.

You might find this of interest:

http://forum.theorchidsource.com/cgi...=000089#000005


You may be right - but I am not looking to establish equilibrium. Humid
air
is lighter than dry air, so there will be continuous evaporation, rising
of
the humid air from the tray past the plants and into the room. I am aware
that some air movement is good. But again, I am trying to create an "OK"
environment for orchids in a room that is regularly used, and I know that
I
will never be able to create an ideal environment or even close to it as I
could in a dedicated orchid room. I have considered partially enclosing
the
shelves with clear plastic. In any case, the trays cannot hurt the
humidity
situation and will serve to catch overflow from watering if nothing else!


--
Peter Aitken

Remove the crap from my email address before using.

"Ray" wrote in message
...
OK, Peter. You're going to have to help me with this one:

You stated "Humid air is lighter than dry air". How can that be? Humid
air
is dry air containing water vapor, so how can (stating it mathematically)
X + Y X ?

In reality, the heavier, humid air will stay settled around the plants
until
diffusion or forced dispersion moves it away.

You're right: humidity trays may not help much, or at all, but they do
protect the furniture!

--

I know it's counter-intuitive but it's true - humid air is lighter than dry
air. Water vapor is lighter than air. In perfectly dry air you have 100%
air. In humid air you might have 90% air and 10% water vapor (I made those
figures up but they will serve to illusrtate). The water vapor replaces some
of the air, it does not add to it. So, lighter water vapor replaces heavier
air, the end result is lighter. I wish I could explain it better, but I
remember this fact distinctly from when I studied meteorology.


--
Peter Aitken

Remove the crap from my email address before using.

Actually, you're correct! I am a ceramic engineer by background, so studied
psychrometry as it applied to drying management in ceramic bodies, but that
was apparently longer ago than my memory permitted!

Well then, back to the efficacy of the humidity tray - in addition to
entropy and fans, the density plots against it too. Sheesh.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!
..
"Peter Aitken" wrote in message
m...
"Ray" wrote in message
...
OK, Peter. You're going to have to help me with this one:

You stated "Humid air is lighter than dry air". How can that be? Humid
air
is dry air containing water vapor, so how can (stating it mathematically)
X + Y X ?

In reality, the heavier, humid air will stay settled around the plants
until
diffusion or forced dispersion moves it away.

You're right: humidity trays may not help much, or at all, but they do
protect the furniture!

--

I know it's counter-intuitive but it's true - humid air is lighter than
dry
air. Water vapor is lighter than air. In perfectly dry air you have 100%
air. In humid air you might have 90% air and 10% water vapor (I made those
figures up but they will serve to illusrtate). The water vapor replaces
some
of the air, it does not add to it. So, lighter water vapor replaces
heavier
air, the end result is lighter. I wish I could explain it better, but I
remember this fact distinctly from when I studied meteorology.


--
Peter Aitken

Remove the crap from my email address before using.

Actually, you're correct! I am a ceramic engineer by background, so studied
psychrometry as it applied to drying management in ceramic bodies, but that
was apparently longer ago than my memory permitted!

Well then, back to the efficacy of the humidity tray - in addition to
entropy and fans, the density plots against it too. Sheesh.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!
..
"Peter Aitken" wrote in message
m...
"Ray" wrote in message
...
OK, Peter. You're going to have to help me with this one:

You stated "Humid air is lighter than dry air". How can that be? Humid
air
is dry air containing water vapor, so how can (stating it mathematically)
X + Y X ?

In reality, the heavier, humid air will stay settled around the plants
until
diffusion or forced dispersion moves it away.

You're right: humidity trays may not help much, or at all, but they do
protect the furniture!

--

I know it's counter-intuitive but it's true - humid air is lighter than
dry
air. Water vapor is lighter than air. In perfectly dry air you have 100%
air. In humid air you might have 90% air and 10% water vapor (I made those
figures up but they will serve to illusrtate). The water vapor replaces
some
of the air, it does not add to it. So, lighter water vapor replaces
heavier
air, the end result is lighter. I wish I could explain it better, but I
remember this fact distinctly from when I studied meteorology.


--
Peter Aitken

Remove the crap from my email address before using.

"Ray" wrote in message
...
Actually, you're correct! I am a ceramic engineer by background, so
studied
psychrometry as it applied to drying management in ceramic bodies, but
that
was apparently longer ago than my memory permitted!

Well then, back to the efficacy of the humidity tray - in addition to
entropy and fans, the density plots against it too. Sheesh.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!
.


My son is a ceramic engineer - but has yet to be bitten by the orchid bug!


--
Peter Aitken

Remove the crap from my email address before using.

"Ray" wrote in message
...
Actually, you're correct! I am a ceramic engineer by background, so
studied
psychrometry as it applied to drying management in ceramic bodies, but
that
was apparently longer ago than my memory permitted!

Well then, back to the efficacy of the humidity tray - in addition to
entropy and fans, the density plots against it too. Sheesh.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!
.


My son is a ceramic engineer - but has yet to be bitten by the orchid bug!


--
Peter Aitken

Remove the crap from my email address before using.

In article ,
"Peter Aitken" wrote:

Can someone point me to an online source for humidity trays? I'm not having
any luck locally. THanks.



i use pyrex baking dishes (machine washable, and they were on sale. :-)


the plants sit on either plumbing bits or little wire boxes i make out
of hardware cloth.

caveat: i'm a windowsill grower, this probably wouldn't work in a large
space.

--j_a

Quite right, Peter.

Water weighs in at 18 grams/mole. Air is ~20% oxygen (32
grams/mole) and 80% nitrogen (28 grams/mole), for an average of about 28.8
grams/mole. A mole of water vapor takes up about the same volume as a mole
of nitrogen, air, or nitrogen/air mix (very approximately- I'm sure
someone will shout out the Van der Waals equation here). As a result,
water vapor is prone to escape.

I once had a senior research chemist (synthetic organic and
inorganic stuff- nobody here would recognize the name, but EVERYONE is
familiar with his work) point out to me in the lab that when washing
flasks, once the remaining water has drained, flasks actually dry faster
when not on the rack, as water vapor escapes faster when right-side up.

For humidity trays, however, any such influences are rapidly
diluted by any air movement, and little benefit is achieved on the local
scale.

The e-mail address in the header is not valid. Send no mail there.


-AJHicks
Chandler, AZ

"Peter Aitken" wrote in message
om...
"francis marion" wrote in message
news:tvwgd.329842$MQ5.185068@attbi_s52...
I'm not quite sure what you mean by "Humidity trays". For my
trays I went
to a local nursery and bought a couple of the dark green/black
plastic
trays
that gardeners use to start seeds from.

They are about 24" long x 12" deep x 3 "tall. Place an inch or so
of
clean,
washed gravel and add water. I then take a piece of the plastic
"egg-crate"
white, plastic fluorescent light cover, that I buy at the local
hardware
store. Cut it to fit inside the green trays and place my plants
on top of
those.

I don't know if your looking for something fancier than that. But
mine
work
great for me.

Hope this helps,

Francis Marion



That's exactly it - although something nicer looking than plastic
would be
good. But none of the garden stores have them, perhaps because it is
not
Spring.


--
Peter Aitken

Remove the crap from my email address before using.





You can try Parkside
http://www.parksideorchids.com/supplies.htm

Ed

"Peter Aitken" wrote in message
om...
"francis marion" wrote in message
news:tvwgd.329842$MQ5.185068@attbi_s52...
I'm not quite sure what you mean by "Humidity trays". For my
trays I went
to a local nursery and bought a couple of the dark green/black
plastic
trays
that gardeners use to start seeds from.

They are about 24" long x 12" deep x 3 "tall. Place an inch or so
of
clean,
washed gravel and add water. I then take a piece of the plastic
"egg-crate"
white, plastic fluorescent light cover, that I buy at the local
hardware
store. Cut it to fit inside the green trays and place my plants
on top of
those.

I don't know if your looking for something fancier than that. But
mine
work
great for me.

Hope this helps,

Francis Marion



That's exactly it - although something nicer looking than plastic
would be
good. But none of the garden stores have them, perhaps because it is
not
Spring.


--
Peter Aitken

Remove the crap from my email address before using.





You can try Parkside
http://www.parksideorchids.com/supplies.htm

Ed

I use trays from fast food restaurants.They are solid and do not rust. I put
in them: Fluorescent honeycomb or gravel or carpet underlay. Honeycomb is
the easiest to clean.Whatever everybody has to say about humidity is of not
much importance to me. Because, when watering, these trays absorb the
surplus water.
Ed Cormier

I use trays from fast food restaurants.They are solid and do not rust. I put
in them: Fluorescent honeycomb or gravel or carpet underlay. Honeycomb is
the easiest to clean.Whatever everybody has to say about humidity is of not
much importance to me. Because, when watering, these trays absorb the
surplus water.
Ed Cormier

Try Cal West Orchid Supply
http://www.orchid-supplies.com/humidity_trays.html

.. . . Pam
Everything Orchid Management System http://www.pe.net/~profpam/page3.html

---------------------------------------------------------

"Edward Rutter Jr." wrote:

"Peter Aitken" wrote in message
om...
"francis marion" wrote in message
news:tvwgd.329842$MQ5.185068@attbi_s52...
I'm not quite sure what you mean by "Humidity trays". For my
trays I went
to a local nursery and bought a couple of the dark green/black
plastic
trays
that gardeners use to start seeds from.

They are about 24" long x 12" deep x 3 "tall. Place an inch or so
of
clean,
washed gravel and add water. I then take a piece of the plastic
"egg-crate"
white, plastic fluorescent light cover, that I buy at the local
hardware
store. Cut it to fit inside the green trays and place my plants
on top of
those.

I don't know if your looking for something fancier than that. But
mine
work
great for me.

Hope this helps,

Francis Marion



That's exactly it - although something nicer looking than plastic
would be
good. But none of the garden stores have them, perhaps because it is
not
Spring.


--
Peter Aitken

Remove the crap from my email address before using.



You can try Parkside
http://www.parksideorchids.com/supplies.htm

Ed

Try Cal West Orchid Supply
http://www.orchid-supplies.com/humidity_trays.html

.. . . Pam
Everything Orchid Management System http://www.pe.net/~profpam/page3.html

---------------------------------------------------------

"Edward Rutter Jr." wrote:

"Peter Aitken" wrote in message
om...
"francis marion" wrote in message
news:tvwgd.329842$MQ5.185068@attbi_s52...
I'm not quite sure what you mean by "Humidity trays". For my
trays I went
to a local nursery and bought a couple of the dark green/black
plastic
trays
that gardeners use to start seeds from.

They are about 24" long x 12" deep x 3 "tall. Place an inch or so
of
clean,
washed gravel and add water. I then take a piece of the plastic
"egg-crate"
white, plastic fluorescent light cover, that I buy at the local
hardware
store. Cut it to fit inside the green trays and place my plants
on top of
those.

I don't know if your looking for something fancier than that. But
mine
work
great for me.

Hope this helps,

Francis Marion



That's exactly it - although something nicer looking than plastic
would be
good. But none of the garden stores have them, perhaps because it is
not
Spring.


--
Peter Aitken

Remove the crap from my email address before using.



You can try Parkside
http://www.parksideorchids.com/supplies.htm

Ed

I use a bunch of old sheet film developing trays that a local phot lab
was discarding. I just scrubbed them thoroughly and put in a layer
of damp pea gravel.

Some of these trays are real beauties, stainless steel and big enough
for 16X20 negatives or prints.


J. Del Col