This is from a private conversation I was having. Much more technical than I usually share on the open forum. Thought I'd share it with y'all before I head out on vacation.
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Heat seeks equilibrium. It (heat) wants to find equilibrium by flowing to cold areas of a closed system. It, like electrons, will take the path with the lowest resistance/thermal impedience mismatch.
In an atty it has three paths. First Into the posts, then into the juice and then into the air.
The wire mass heading to the posts is the current. The temperature differential between the coil and the posts is the pressure. The more mass the legs have the more heat can escape that route. Basically small wire is a bottleneck to this flow. This can be seen when you glow a coil. The legs and outside wrap are loosing a good bit of heat to the posts and will never glow like the middle of the coil.
This is lost heat.
Next you have heat flow to the juice. The heat wants to flow into the juice but the size of the wire and contact area of the wire and wick determines rate of flow. A 30ga wire has a width of 0.25mm, a 24ga wire has a width of .51mm. A 30ga wire has ~40% of its surface area in contact with the wick. A 24ga wire has ~20% of its surface area in contact with the wick. These are general imbedding figures.
Here is a example of two coils. One 24ga, one 30ga.
They are both 5.5mm wide and have the same ID
View attachment 598923
I cut off the legs at the sharpe mark.
View attachment 598925
And measured them
View attachment 598927
Then maths
View attachment 598921
As you can see the they both have very close to the same total surface area. The 24ga coil has twice the mass. So not only does the heat generated on the outside of the coil have twice as far to travel through the wire to the juice but the contact patch to the wick is half the size.
This is why thick wire heats more air than thin wire, even though both coils have basically (2.7% difference) the same total surface area. The outside of the coil simply gets hotter.
The practical effect of this is the 30ga coil will evaporate ~twice the amount of juice in a 4 second puff than the 24ga coil at the same wattage.
Basically, if you want to win a cloud competition build with small wire in a 2 or 3 wire parallel configuration (Depending on desired resistance)
View attachment 598931
I'm not very good at communicating these ideas as my mind moves much faster than I can type. I hope this makes sense.
Sincerely, Boden.
), and if I had a question about coils, watts, volts, thermodynamics, etc, you would be the first person I would ask. You are a valuable asset to us all with your knowledge. Thank You for all the knowledge you have imparted to us all. 
