High Temperature in Cold Outer Space
How does one explain the concept of the temperature being perhaps 700 degrees C
high up in the atmosphere, but that an person would freeze to death (if not
succumb to some other fate) if exposed up there?
And what would it mean to have a temperature of 700 degrees C in empty space?
Thanks for any hints on this, I am sure it is a simple idea.
Empty space is neither hot nor cold: these are qualities usually assigned to the matter which fills it. When this matter is dense, its temperature influences the temperature of anything else placed there. However, if that "matter" is just very rarefied gas, the temperature of whatever else occupies that space (astronaut, spacecraft etc.) may be determined by other factors.
The upper atmosphere is very rarefied. As its atoms absorb short wave radiation from the Sun (extreme ultra violet etc.), they get very energetic, that is, very hot. However, their density is low, so the density of their heat energy is negligible, and anything that touches them, e.g. a satellite, can easily absorb this heat. Instead of melting, it cools down the atoms which hit it. The temperature of the satellite is determined by the balance of heat it absorbs from sunlight, against the heat it radiates to space in the infra-red, both much bigger items in the heat budget.
Another example. Plasma containment experiments in the lab (conducted with an eye towards possibly extracting energy from the fusion of hydrogen nuclei) can involve rarefied plasmas at a temperature around a million degrees, held trapped by magnetic fields. These fields tend to develop instabilities, much to the annoyance of experimenters, who try to foil them. If such a plasma gets too unstable, it may touch the wall. But the result is not the wall evaporating, rather the plasma cools down and recombines.
Yet another example, somewhat similar. You read about the electric field in the atmosphere, which gets stronger beneath thunderstorms. Supposedly, there exists a potential difference of 150 volts (this number from one report I saw) or more, between the level of our heads and the ground. Why don't we feel it? Because our body is a conductor of electricity, and easily shorts out the field. Very little electric charge is involved and we feel nothing.
Bottom line: Quality (temperature, voltage...) is important, but without a large enough source of energy behind it, it alone will not accomplish much.