The human perception of temperature is unreliable. For example, a metal chair feels colder than a wooden chair when indoor. But the same metal chair feels hotter than the wooden chair when they are out in the hot sun. But we know that both chairs are at the same ambient temperature!
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This is why we invent thermometers. In the school lab, I found this Galileo Thermometer. It works on the principle that the density of water changes with temperature, thus making the differently weighted glass balls rise and fall. It is one of the lousiest thermometers I have seen. It takes forever to respond (thanks to its heat capacity), it cannot measure localized temperature, suffers from poor resolution, it is bulky, etc. But as a toy, it is fascinating to watch.
xmPhysics 