Negative forty degrees. It’s a special temperature.
When it’s forty below outside, not only can you throw boiling water in the air and observe what's called “deposition” (a gas turning directly into a solid)—but you can also ignore what kind of thermometer is on the wall. Negative forty is the only temperature reading that is the same in Celsius and in Fahrenheit.
Our biosphere is chock-full of meteorological oddities: freakish cold snaps, dust devils, rains of frogs or fish. Here is a sampling of the oddest of the odd:
Red Sprites and Blue Jets
First proved to exist in 1989, these lightning-like flashes occur above thunderstorms. Way, way above them. In a storm, common lightning bolts are five to ten miles high—they’re the ones we know, the bolts that split trees, blow circuit breakers, and stun golfers. But above a storm’s cauldron of rain and hot electrical activity, other things are going on.
Occasionally, a storm cell will release a giant, reddish charge into the upper atmosphere—called a “sprite,” these discharges of energy can top out at thirty to fifty-five miles high, practically high-fiving the ionosphere. Sprites are triggered by a large, normal lightning flash lower down. Less common—and unrelated to surface lightning—are “blue jets,” another upward-moving bolt of energy occurring at lower altitudes (twenty-five to thirty miles up) and giving off, as the name suggests, a bluish light.
St. Elmo’s Fire
It's mentioned over and over throughout history, often in nautical accounts—in the writings of Julius Caesar and the letters of Charles Darwin, in Robert Burton’s Anatomy of Melancholy and Herman Melville’s Moby-Dick: a violet-bluish glow on the tips of masts, chimneys, lightning rods, even the horns of oxen. These crackling, plasma globe–like electrical emanations—named for St. Erasmus (or Elmo) of Formiae, the patron saint of sailors—have been scaring the pants off sailors for millennia. Melville writes: “All the yard-arms were tipped with a pallid fire ... each of the three tall masts was silently burning in that sulphurous air, like three gigantic wax tapers before an altar” (Moby-Dick, Ch. 119, “The Candles”).
St. Elmo’s fire has rarely, if ever, been caught on film. And it is not the same as ball lightning, a much more debatable phenomenon. The latter is supposedly a free-floating ball of electrical charge, said to zip around erratically, often coming in windows or doors before sizzling out.
Lenticular Clouds
These have something in common with ball lightning (if that can be said to exist). Both are periodically mistaken for UFOs. Lenticular clouds have a very distinct structure: they look like opaque saucers or lenses (lenticula is the Latin diminutive for “lens”). They commonly form when moist air is forced into a hump over a mountain—this air condenses into cloud and, as it dips down again, evaporates back into water vapor. A lenticular cloud may look inert, but it’s more like the standing foam on a flowing wave.
Another type of capping cloud, called a “pileus,” forms over other rising air masses rather than mountaintops. Pilei can be seen over cumulus clouds, nuclear explosions, even volcanic eruptions—as on June 12, 2009, when the International Space Station took this startling video-like series of photos of Sarychev Peak, a violently exploding Russian volcano.
