At work, I deal with molten metal. It's hot stuff. Incidentally, I'll remind everyone out there that we're all very familiar with water as a solid, liquid and gas. We're all used to terms like, freezing, melting, boiling, etc. It's no different for metal, or liquid nitrogen. All the elements still do the same things, just not at 0° and 100°. (The whole expanding when freezing thing is fairly unique to water though. If you want to know half a dozen more unique things about water, ask Suzanne.)
Anyway, because our molten metal is really hot 1000°C, give or take, we have fancy thermometers to measure the temperature. The only down side is that when you're spending your evening letting the things cool down, the thermometers quit working. They've got some lower limit why the don't work (I'd explain why, but that would require the Stefan-Boltzmann law and you simply don't care) so as they cool, once they're somewhere below 800°C (roughly) the thermometer doesn't say anything more specific than "cold". (Remember, cold is just a relative meaning. "Colder than what?" is the important question.) But that leaves me curious as to what the temperature is like in there. The metal glows red when it's hot, so color and brightness is an indication of temperature (whoops, that's pretty much the Stefan-Boltzmann law, sorry) but that gives out not long after my thermometers. So our official technique: stick your hand in front of it and feel how much heat is coming out the little window. But if you want a more precise measurement? Easy. I use my face. (It's much more sensitive to heat.)
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