content: Keep in mind that this was photographed in the infrared. The coloring was added afterwards. Infrared in some cases allows for easy coloring because you can choose the specific bands of heat to colorize without the need to select borders. The sky, baring atmospheric emissions, will typically be near zero degrees kelvin. The clouds will be warmer. The tree trunk, since it is shaded by the leaves will be cooler, while the leaves themselves will reflect some sunlight and have their own signature. An of course the ground and the "straw" will be hot because it is baking in the sun. And yes, hay can be green but is normally golden colored. Hay that is sold to ranchers has been stored in a barn long enough that the chlorophyll dissipates.