This is a really practical question, but I can't find anything on Google.
My metal chainlink fence is rusting and I have noticed that where the metal from one wire makes contact with another wire there is a point of bright orange glowing which sparks if the metal is moved. It does not feel at all warm to the touch, though outside temp is hovering around 0C right now.
Back story: I noticed it tonight when I went out to toss the compost in the leaf bin, and saw a very bright orange glow. I got a light and inspected it a bit closer with my wife and she noticed a second spot on the fence. Both were at junctions in the chain, where there was significant corrosion. Those locations were both heavily corroded such that visible gouges were forming at the junction where the bright orange spot was. I gave the fence a kick and both spots threw off a good number of very bright white and orange sparks. It did this about 5 or six times then stopped, and the metal was no longer orange in those spots. It did not feel hot to the touch either, though I didn't touch it when it was orange. I'm perplexed but figured it seemed like a good questions for some chemists, as I am guessing it has something to do with the corrosion process.