East Window versus West Window

[Paul]

Originally Posted by Orchid Whisperer

In the morning, the east/morning sun is more likely to be cutting through more haze/fog/humidity than in the west/evening. Hence dew in the morning. That cuts down light intensity.

That lower morning temperature may be a factor too. Though I think it is more important for plants grown outdoors.

Originally Posted by Ray

The hydroxyl radicals within water (the O-H bonds) have a resonant frequency that is a close match to part of the infrared spectrum, which might attenuate some of the morning heat.

I do not have any data to support this following premise, but follow my logic if you will ...

The diffusion of light factor through fog/moisture in the air as OW mentioned could very well play a role in lower morning light intensity. However, a possibly equally or more significant factor would be what Ray alluded to in combination with another idea put forth by OW. First some ground work:

1) Water is a "heat sink" ... that is a basic fact. Compared to many substances, water requires a surprising amount of energy to raise its temperature, and loses that energy quite slowly. (Note: It is not an uncommon practice in some northern areas for gardeners to protect early spring plantings from unexpected frosts by placing a "water wall" around plants. Theoretically, during the day, the water is heated by sunlight and over the course of the night releases enough heat to prevent frost damage. Never having put this to the test myself, I am forced to rely on some hearsay as to the efficacy of this use.) In addition to energy absorption to raise temperature, even more energy (a surprisingly high amount, in fact) is required for water to undergo a phase change or "change of state" (solid --> liquid, liquid -->gas).

2) The infrared part of the light spectrum is the heat portion of the spectrum. (Interesting science tidbit -- at least to me -- there are animals like some snakes which are capable of "seeing" in the IR spectrum.)

3) Fog is a colloid -- a suspension of water droplets in air.

So over the course of the night, water vapor (a gas) in the air often loses enough energy (cools) to condense into water droplets which, if small enough, remain suspended in the air. Some of the IR (heat) energy of morning sunlight is absorbed by the suspended droplets -- warming them and giving them the energy needed to undergo the phase change to vapor. Over the course of the day, ambient temperatures continue to rise as the airborne water reaches its absorption capacity of heat energy at that intensity. Thus the commonly observed phenomenon of it being cooler in the morning than afternoon.

Now having said all that, while AC obviously offsets the impact of outdoor temps, it is also commonly observed that temps will be higher during the summer months right by the window than deeper within the AC cooled room. By extension, it would be very plausible for south or west facing window areas in the northern hemisphere to be warmer, as a result, than the east or north facing ones.

Another point of note, such differences between east vs west are themselves can be significantly impacted by many factors such as: season; climate (arid areas such as Arizona will have far lower outdoor RH than places like Hawaii or Louisiana, for example); and presence or absence of trees, awnings, or other obstacles to the sunlight shining on/in/through said windows.

[Leafmite]

I grow some higher light orchids in a West window. My Cattleya aclandiae is very happy as are all my walkeriana hybrids and the Angraecum magdalenae. Basically, what grows well in a South window without any curtains will usually grow well in a West window, too.

The problem with any plant is heat + light - breeze. If you open your windows in the summer, the plants should be fine. That is what I do.

[Optimist]

Water is a heat sink unless it is agitated. I have a little solar powered pump that keeps the water in an outdoors fish tank moving. You will notice that outside fountains have cool water, not hot water even when in the full sun. Anyway...

I like east windows. Phrags for instance, always seem to grow on east facing slopes in Equador. They also prefer to be near running water (for cooling?) and in the full sun. But I would wager that if the water was still and "hot" there would be no cooling factor. (obviously, wind or breeze is also cooling so that their leaves can take greater amounts of sun). I've seen mention of cattleyas growing in eastern slopes in Colombia, but have not researched this topic for Brazilian Catts. I agree to opening your windows. For those who fear neighborhood crime, fans are okay too.

[estación seca]

Originally Posted by Optimist

Water is a heat sink unless it is agitated. I have a little solar powered pump that keeps the water in an outdoors fish tank moving. You will notice that outside fountains have cool water, not hot water even when in the full sun.

Circulating ponds and fountains evaporate more water than when still, and this cools the remaining water some. Here in metro Phoenix a pond with a fountain is still hot in summer. Swimming pools are built with water return through spray jets, which evaporatively cools some of the water. Still many people don't want to get in a swimming pool here in the summer because they think the water is uncomfortably warm.

A lot of double-glass high-insulation windows have coatings to decrease incoming heat and light. If you can put your hand near the glass on a sunny day, and not feel any heat at all, you have this kind of window. Unfortunately they are terrible for plants. Most new construction in the Southwest has this kind of window.

Yet another reason people think it's their fault when they can't grow house plants. It's similar to Microsoft trying to make users think any Windows problem is due to the user.

[Mountaineer370]

Originally Posted by estación seca

A lot of double-glass high-insulation windows have coatings to decrease incoming heat and light. If you can put your hand near the glass on a sunny day, and not feel any heat at all, you have this kind of window. Unfortunately they are terrible for plants. Most new construction in the Southwest has this kind of window.

Yet another reason people think it's their fault when they can't grow house plants. It's similar to Microsoft trying to make users think any Windows problem is due to the user.

I'm starting to think this may be part of my problem. (new, very efficient windows). My orchids grow nicely, putting out plenty of new roots and foliage, but I have trouble getting anything to bloom.

My African violets, on the other hand, bloom like crazy in a north window. Go figure.

I've been thinking of starting a couple new threads to ask specific questions. Stay tuned......

[malteseproverb]

Cheri, in an earlier post you noted that because someone remains in your house most of the time, your house remains temperature controlled and therefore does not fluctuate throughout the day. This could be a reason some of your plants resist blooming, too. I used to live in an apartment where the thermostat was set to 70 degrees all winter and, in addition to drying my plants out, it made it more difficult to trigger blooming in some of my orchids. It's something to look into. What kind of orchids are you growing?

[Dollythehun]

Just FYI, you can buy windows that are build to block sun as ES says, or to block the cold. I'm not an expert at this but, we are looking for new windows, and this fact came up.

[Mountaineer370]

MP, you are right, we keep our house set at a constant temperature, day and night. It's a few degrees cooler in the winter but still doesn't drop below 70 degrees. I wish I had a separate room where I could keep my orchids and it wouldn't matter if I let the temps drop in that room, but, unfortunately, the only place I can keep them is in my kitchen/dining room, and temps remain the same throughout my small house. I'm often unable to sleep and will be up pacing around at night, and I don't like to be cold when I'm doing that.

You asked what kinds of orchids I have. Right now, I have five phals, three paphs, one catt, and four oncidium hybrids. A couple of my phals are the only ones that have rebloomed under my care. Several of the plants are fairly new for me, so I don't know yet how they will do, but the catt and three of the oncidiums have been with me for between a year and a half to two years and still no sign of blooming.

Dolly, I'll have to hunt up our receipts for the windows and see exactly what we got. My memory is that insulation from outdoor temperature extremes was the prime focus. We weren't looking so much to block light, but I think at least the UV coating is pretty much standard on their better quality ones (which these were).

[Ray]

The thermal control coatings being referred-to are the "Low-E" or low emissivity coatings.

They function by blocking long-wave IR while allowing shorter-wave IR to pass. In winter, the IR from the sun strikes objects indoors, where they are reradiated as longer-wave IR (heat), which is not allowed to escape. In summer, when it is really hot outside, the heat - the long-wave IR - is prevented from entering the home, keeping it cooler. As windows now are dual-paned, the orientation of the one, coated inner surface is determined by your predominate climate. In a hot climate, it will be on the inside of the outer pane, and on the inner pane in a predominantly cold climate.

While the coating does reduce the intensity of the light passing through it, it is only a few percent, and it is pretty uniform across the visible spectrum, so has very little impact upon plant growth.

I was the technical manager of the group that invented that glass coating technology, but I cannot speak to the impact of the UV blocking coatings.

[orchidsarefun]

Some of the best plants - size, health and blooms - I've ever seen are grown in an indoor space that is equidistant from south, east and west facing windows. Basically very bright light and some dappled sun.
I've only ever been able to replicate that when my plants are outdoors. It's an ideal.