The DMG description differentiates standard infravision (anything up to 60 feet, which PC races and most monsters have) from improved infravision (anything with a longer range than 60 feet, which a handful of dungeon monsters, not most, have [trolls being the only critter in the 1e MM that I could find] as well as demons and devils and such).
Standard infravision:
1e DMG, p59 wrote:Characters and various creatures with infravisual capability out to 60' (standard) are basically picking up radiation from their surroundings. Therefore they note differences in thermal radiation, hot or cold. They do not "see" things which are the same temperature as their surroundings. Thus, a room in a dungeon might look completely blank, as walls, floor, ceiling, and possibly even some wooden furniture within are all of the same temperature. Openings in the walls should show up rather plainly, as space anywhere else will,
[...]
Note also that monsters of a very cold or very warm sort (such as a human) can be tracked infravisually by their footprints. Such tracking must occur within 2 rounds of their passing, or the temperature difference where they had trodden will dissipate.
[...]
lnfravision outdoors enables the individual to see figures which are warm or cold at 100' to 300', depending on temperature extremes. Vision is otherwise equal to a bright, starry night, with full moonlight.
Improved infravision:
1e DMG, p59 wrote:Creatures with infravisual capability of unusual nature, such as those which see infrovisually to 90', are actually emitting infrared radiation from their eyes and seeing what is within this visual range by receiving the reflected radiation. Such creatures can easily distinguish floor, ceiling, wall, and other areas, as well as furnishings within an area. The eyes of all such creatures will appear as very brightly glowing red when observed by any other creature with standard infravision.
The glowing-eyes bit isn't really mentioned anywhere else in the rules that I can find, but neither is it contradicted. It does show up in several places in the novels, though, mostly in the FR drow books.
As for ultravision being mostly useless underground, the DMG description notes that from the start, and most monsters with ultravision said to see well underground are those with infravision as well; "They have both ultravisual and infravisual capabilities" is a common line in monster descriptions. Also, the rules don't say that "magic" in general generates ultraviolet light, just that magic weapon illumination does.
1e DMG, p59 wrote:Ultravision is the ability to see radiation above violet in the normal visible spectrum. Unless this ability is of highly unusual nature, so as to be able to see far into this spectrum, ultravision will not be useful Underground (where radiation is screened out) without some source of ultravisual emanation. Magic weapons which shed illumination spoil ultravisual capability, just as heat does infravision. As noted in PLAYERS HANDBOOK, ultravision enables the viewer to see outdoors at night as if he or she were in twilight, so vision extends clearly for about 100 yards, dimly to about 300. On particularly cloudy nights, ultravisual capability is reduced to about half normal, i.e. clear sight to 50 yards, dim to 150 yards.
And a section on special vision underwater that gets the science of infravision wrong, as Frank noted, but that also notes the limitations of ultravision without sunlight:
1e DMG, p56 wrote:lnfravision and ultravision are useful underwater, and their distance limits are the same as in dungeon settings. There are some problems, however: infravision users may become confused due to shifting currents and layers of different-temperatured water, as water exchanges heat more slowly than air and therefore is of a less even temperature. Distance of ultravision is halved at 100' depth and reduced to zero below 200' as ultraviolet "light" does not penetrate beyond that depth in sufficient quantities for sight.
And drow equipment is not powered by ultraviolet light, rather by "unknown radiations" (that would later be called "Faerzress" in FR):
1e Fiend Folio, p34 and D3: Vault of the Drow, p5 wrote:Special Note Regarding Drow Cloaks, Armor, and Weapons: All of these items have special properties, although none of them radiate any magic. The items are made under the conditions particular to the strange homeland of the Drow, for this place has unknown radiations which impart special properties to these cloaks, armor and weapons. When such items are exposed to direct sunlight a rotting process sets in. The process is absolutely irreversible, and within 2 weeks cloaks will fall to shreds, while armor and weapons become pitted and unusable. If items are not exposed to sunlight, they will retain their magical properties for 31-50 days before losing them, and if they are exposed to the radiation of the Drow homeland 30 or so days, they will remain potent. Items not spoiled by sunlight will eventually lose their special properties if not exposed to the special radiation, but they will remain serviceable as normal cloaks, armor, shields, swords, maces, etc.
Drow sleep poison decays instantly in sunlight. Its power is lost after about 60 days in any event, and the coating on the small bolts and javelins must be periodically renewed with fresh applications of the fungoid substance. The Dark Elves will often have small barrels filled with several packets of this poison, each sealed to insure the poisonous substance remains fresh for about 1 year.
...nor are all drow cities built in caverns with sources of ultraviolet light, rather the Vault of the Drow in particular has one large orb and many smaller orbs in the ceiling made of a particular mineral that allows infravision, ultravision, and normal vision to all work in the Vault:
D3: Vault of the Drow, p11 wrote:The true splendor of the Vault can be appreciated only by those with infravision, or by use of the roseate lenses or a gem of seeing. The Vault is a strange anomaly, a hemispherical cyst in the crust of the earth, an incredibly huge domed fault over 6 miles long and nearly as broad. The dome overhead is a hundred feet high at the walls, arching to several thousand feet height in the center. When properly viewed, the radiation from certain unique minerals give the visual effect of a starry heaven, while near the zenith of this black stone bowl is a huge mass of tumkeoite — which in its slow decay and transformation to lacofcite sheds a lurid gleam, a ghostly plum-colored light to human eyes, but with ultravision a wholly different sight.
The small "star" nodes glow in radiant hues of mauve, lake, violet, puce, lilac, and deep blue. The large "moon" of tumkeoite casts beams of shimmering amethyst which touch the crystalline formations with colors unknown to any other visual experience. The lichens seem to glow in rose madder and pale damson, the fungi growths in golden and red ochres, vermillions, russets, citron, and aquamarine shades. (Elsewhere the river and other water courses sheen a deep velvety purple with reflected highlights from the radiant gleams overhead vying with streaks and whorls of old silver where the liquid laps the stony banks or surges against the ebon piles of the jetties and bridge of the elfin city for the viewers' attention.) The rock walls of the Vault appear hazy and insubstantial in the wine-colored light, more like mist than solid walls. The place is indeed a dark fairyland.
The 3e Underdark book later established that the illuminating radiation from the tumkeoite-to-lacofcite decay process and the equipment-enhancing radiation from the Faerzress were one and the same, but this wasn't necessarily the case at the time; either way, it wasn't actual ultraviolet light in the Vault of the Drow, just magical radiation that was also visible with ultravision.