By that I mean are there any natural phenomena that use a low entropy energy source to move heat against a temperature gradient. I know that there are a lot of things that can be interpreted as heat engines, like hurricanes, but I wanted to know if the opposite also happens in nature.
Warm blooded creatures use tricks like evaporative cooling and flow control to move heat around. Some birds, for example, have the veins and arteries in their legs tangled up in such a way that the blood headed toward their feet can give heat back to the cooled blood that's headed back toward the heart. This prevents a lot of heat loss, but doesn't actually move heat from low- to high-density regions within the body. Most of the heat involved comes from chemical processes within the cells releasing energy that, ultimately, came from sunlight.
Convection cur
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