Thanks.
Yea, I'm still really interested in this. I'd *guess* the reason (for the higher temps on the lower leaves) is because the upper leaves are transpiring more - due to the higher rate of photosynthesis (getting more light, doing more 'work'). It almost seems counter intuitive, but they're cooling themselves more than the lower leaves is my somewhat educated/experienced guess. This is probably moreso the case with LEDs, because there's no direct infrared heating coming down from the lights to actively heat the leaves (especially the upper versus the lower ones).
That make sense?
I took an interest in this when I started IR shooting several plants (some not doing so great) and noticed that the plants that weren't doing so great were actually warmer than the ones that were. Again, I thoguht it must be related to the rate of transpiration. The plants that were struggling/recuperating weren't drinking/transpiring as much, so less cooling factor.
Sometimes I feel leaves (upper canopy) with my fingers and the actually feel cool - compared to the rest of the plant (limbs) and other objects at that height. They're 'sweating'/cooling, I think.
Cool.
