In a recent discussion heat and transport has become a point of contention. The relationship of heat of a thing (the ground, or you in a sleeping bag … or more distantly the temperature of your coffee in that thermos) depends on a few parameters. At equilibrium (not your coffee cup any more) heat transfer in equals heat transfer out. The earth, radiated at the sun, is (basically) at a time averaged equilibrium. The claim of the global climate warming crowd is that additional insulating effects raise the temperature. How does this work if the energy in still equals the energy out? Well, to first order, the energy flowing out depends on two factors, the first being the difference in temperature between the two regions and a factor dependent on the geometry of the interface and the heat conductivity of the interface. If you add insulation (reduce the heat conductivity of the interface) then to have the same amount of energy flowing out the heat differential has to be larger, i.e., in bed when you add blankets you warm up (the heat differential between outside the bed and snug in the covers rises).
It has been claimed recently (and this needs substantiation) that wind farms change the turbulence of the air in the region around them, decreasing the efficient mixing of air between low and high altitudes, i.e., decreasing their effectiveness at heat conductivity. Hence the delta T rises (the ground temp) rises in that region. This change in conductivity is what drives the temperature change at the ground. The suggestion is, that then if wind farming becomes a non-trivial fraction of the earths cover this is just the same problem as adding greenhouse gases, the result is increased global average temperatures. The same people who thing global warming is problematic should be concerned about this possibility for the same reasons. Those who are not concerned of course, should not use this as an objection against wind farming.