I see a "it's green", "it's blue" discussion starting up. Keep the popcorn ready!
Oh! Btw, definitely green.
If you put a color dropper on it the green and blue channel values are almost identical over large sections, that makes it cyan.
Put it in Lightroom and move the Aqua (cyan) hue slider and the barn goes from deep blue to deep green.
So, what you're saying is that it is half green and half blue?
Yep, almost exactly midway. But only in the mixing sense, not that half of it is green and half of it is blue, none of it is either (practically), it is all cyan/aqua. It really is interesting playing with the three Hue/Saturation/Luminance sliders for Aqua alone, it makes a dramatic difference to the feel of the image.
Colour is a a very important compositional element, the fact that the key element in the smooth image is a strong secondary colour very much adds to the impact of the picture, our brain knows it is a key colour and is "important" but we are not sure why so we keep looking at it all the while on another level our brain is trying to figure out if it is blue or green.