Here’s the phenomena which I observe on occassion and keep wondering if I’m simply imagining things.
Fill ceramic cup with boiling water. Let sit for a few minutes so that the cup actually heats up from the hot liquid inside. Now pour out the liquid (not in your lap). Now observe… holding the cup in your hands place a thumb or someother fingers near the top lip of the cup. You should feel the warmth of the cup but be able to stand the heat without pulling away your fingers. Now slowly add very cold water to the cup as you hold it without spilling it on your hand or rim. Does the rim feel like it’s getting hotter as the cold water fills the cup? It does to me.
Same thing with a hot frying pan when I remove it from teh stove to rinse it. The metal handle may be cool enough to hold the pan indeffinately until I begin to pour cold water in the pan. Then the handle begins to heat up considerably until it too begins to cool due to the cold water being added.
Am I nuts or is heat energy moving in these objects due to the localized introduction of a rapid cooling agent?
Ever put your hand under extremely hot water and have it feel cold for just a few hundred milleseconds before your nervous system sorts things out?
This is an effect known as hysteresis. The Concise Oxford Dictionary defines this term as, “Lagging of effect when cause varies in amount.” The transition or variation in signal strength to your nerves is misinterpreted as its opposite or something different from what it is.
I would tend to say that this is one of the factors at work.
In the case of the frying pan you may also be experiencing the effects of what is know as “intimate contact.” As you load the hot, empty frying pan with cold water the additional weight burden causes one of two things:[ol]
[li]You grip the pan more tightly and therefore enhance the transfer of heat to your hand through increased surface area of grip.[/li]
[li]The increased weight of the pan pushes it down onto your hand even harder and promotes more intimate contact.[/li][/ol]
In the case of the ceramic mug, I think that this is more of a case of hysteresis in sensory signal. There is also a smaller possibility that as a thermal pulse builds up in your flesh that a greater magnitude of signal is transmitted by your nervous system, thereby creating an increased perception of warmth.
We will, however, ignore the possibility that heat is concentrating due to the introduction of a thermally absorptive agent (cold water). Exothermic (heat generating) activity, as a rule, follows the law of entropy (randomization or dissapation). The concentration or migration of heat into one specific location would represent an enthalpic (non-randomizing or organizing) process and defy the laws of thermodynamics by which our local universe operates.
Something which may have a bearing on the OP is that there are two types of sensors (I don’t know what else to call them) in your hands which detect heat and cold. One set fires for both hot and cold, and the other fires only for hot things.
Hear’s a WAG: Perhaps the ones which fire for both are firing again when they go from hot to cold. In the presence of the ones firing for heat, this makes you think things are actually getting even hotter, instead of turning cold.
There was a very cool experiment at the Exploratorium consisting of two copper pipes wound around a bar. In one pipe, hot water. In the other, cold. On one side there was just the hot pipe, on the other there was just the cold, and in the middle it alternated hot/cold/hot/cold.
You could grab the cold section and hold it, or grab the hot section and hold it, but you could not grab the mixed section because it felt like a bad burn. If you touched individual turns of the pipes with your finger in the middle section you could tell it was safe, but the proximity of the hot and cold sections made your hand think it was burning if you gripped a range of pipes.
Zenbeam is right on with his explanation of why this worked. Some sensors are for heat, some are for ‘extreme’, either heat or cold. Firing them both is interpreted as burning.