Comments by "EebstertheGreat" (@EebstertheGreat) on "How people kept stuff cold before refrigerators" video.

@martinbudinsky8912 Do you have any evidence of that? Or even a plausible way it could be true? Or are you just making it up as you go along?
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Wine and cheese and the like are stored in cellars everywhere, not just in Europe. Cellars aren't actually colder than their surroundings,* they just keep a more stable temperature throughout the year. So if your average temperature is pretty low, the cellar is pretty cool year-round. But if the average temperature is high, your cellar is warm year-round. So it doesn't really fix the same issue as ice. Cellars reduce temperature variation. Ice just reduces temperature. *The average temperature below ground might be somewhat warmer or colder than the temperature at the surface, but not by that much.
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@martinbudinsky8912 It is not remotely the same as cold at altitude. The average temperature underground is not colder than the average temperature at the surface. It's usually about the same, varying a few degrees one way or the other. You only get a significant difference if you dig super deep, where it is hotter. It has to be that way, because the ground is only exchanging energy with the air and ground around it. If the ground were perpetually colder than the air, the air (and warm ground below) would warm it up and eventually the ground would be warmer again. There is no physical way it could stay always colder. At high altitude, it really is always colder than at the ground below (or rather, it's colder on average). This is because most of the Sun's energy is absorbed by the ground, not the air, and thus the air is heated from below. Heated air rises and expands, and adiabatic expansion causes it to cool. Thus, higher layers of atmosphere are almost always colder than lower ones (at least up to the middle of the stratosphere, where other effects related to ozone absorption of UV become significant). A cellar will reduce the variability in temperature due to time of day, season, weather, etc. But it won't reduce the average temperature, at least by much, and it could just as well increase it slightly.
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@martinbudinsky8912 Here are some sources. First, ICAX says "the mean annual ground temperature ('MAGT') tends to be around 1°C higher than the MATT [in the U.K.]" (search 'icax uk matt') Second, the NGWA says "The temperature of groundwater is generally equal to the mean air temperature above the land surface. It usually stays within a narrow range year-round." (search 'ngwa groundwater temperature') Third, Kalogirou and Florides state that "from the depth of about 1-8 m (for dry light soils) or 20 m (for moist heavy sandy soils)[,] the ground temperature is almost constant and close to the average annual air temperature" (search 'kalogirou florides ground temperature') I dare you to find a source stating otherwise. Unfortunately, if you try posting a link, your post will be spamfiltered, so I gave Google keywords instead.
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