East Window versus West Window

[Mountaineer370]

This is something that has been bothering me for a long time, and I have not found a satisfactory answer in any of my online searches. I hear all the time, on this board and from many other sources, that for the most part, an east-facing window is fine for most orchids, but beware of a west-facing window, as it may be too hot, the plants could get burned, etc.

This topic came up again in conversation with someone at an orchid show I attended yesterday, and that's what made me decide I was going to try to find the scientifically valid reason for the west-window warnings.

When the sun rises in the east and sets in the west, it is, for all intents and purposes, the same distance from our planet for the whole day. The temperature of the sun does not change from morning to evening. How can the sun coming through a west window possibly be "hotter" than that coming through an east window?

Yes, of course I know that the outdoor temperature generally gets warmer as the day goes on, but I'm talking about indoor growing here, and for most of us, that means a temperature-controlled interior environment.

I can see where differences may arise depending on the size of your respective windows, whether there are any porches or awnings, and whether the window is shaded by trees or structures. That could definitely make a difference. But I am having a hard time understanding the often-given reason that sun coming in a west window is hotter or somehow "stronger" than sun coming in an east window.