Low clouds in Cave Creek Canyon (Photo by Narca)
The wet bark of trees has a different look––how intensely green is the Arizona Sycamore bark! The deepest green looks like a new layer of moss or algae from the recent wet spell, but the more general greenish tinge suggests something else––chloroplasts in the bark. I've looked at those green chloroplasts before, when the trees were dry and the colors paler, without really noticing.
This tree may be like the Gumbo-Limbo of tropical dry forests, which exposes its green bark when it is leafless, and is able to photosynthesize––to make food––to some degree throughout the leafless months. It's never completely dormant that way, and gains the advantage of nourishing itself through the lean times. Both of the tree species have peeling bark, too, which sloughs off any epiphytes like lichens that try to gain a toehold on the trunk and branches. That peeling also exposes the underlying chloroplasts. (The photo below hasn't been altered in any way––it is really that green!)
Are sycamores greener in winter? Have you noticed?
Wet sycamore bark (Photo by Narca)