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231 Varieties of Rain: Frogdrops Keep Falling on My Head

Poor Rob McKenna. He drives a truck, so he’s constantly moving, never in the same place for long. And yet everywhere he goes—city, country, near, far, morning, afternoon—it doesn’t matter, wherever Rob is, it’s raining. He can turn, reverse, zigzag, it doesn’t matter. Clouds just follow him, and to prove it (because who would believe this?) he keeps a log and shares it with his friend Arthur Dent, who says, You should show this to scientists. He does, and the scientists tell him, Rob McKenna, we know what you are. You are a Quasi Supernormal Incremental Precipitation Inducer.

What’s that?

He’s a “Rain God.” That’s the gist. Clouds see him and can’t help themselves. They love him and want “to be near him, to cherish him, and to water him.” And the worst of it is, Rob (a totally fictional character in Douglas Adams’s Hitchhiker’s Guide to the Galaxy) hates rain. Can’t abide it. But the rain doesn’t care. So Rob tries to get along. He turns his curse into a part time job: Hotels and vacation spots pay him not to go there. He becomes a regular at a pub called the Thundercloud Corner, where he sits, grimly staring out the window at … well … at scenes like this:

GIF by tkyle
GIF by “tkyle

But because he spends so much time staring at rain, Rob learns to see rainfall as no one has seen it before; he sees its many shapes, moods. He realizes, in the words of poet Conrad Aiken, that raindrops are “the syllables of water,” that rain can take hundreds of different forms.

There’s lashing rain, sheets of rain, rain pissing, bucketing, pouring. There are drizzles. There are mizzles. But Rob McKenna likes superspecific categories. He’s a taxonomist. And so he creates his own rain glossary; it’s described in So Long, and Thanks for All the Fish—the fourth book in the Hitchhiker’s Guide series—with its 231 different rain types:

There’s “light pricking drizzle which made the roads slippery” (type 33).

There’s “vertical light drizzle” (type 47).

There’s “heavy spotting” (type 39) .

There’s “regular” cab-drumming and “syncopated cab-drumming” (types 126 and 127).

There’s “dirty blatter blattering against his windscreen so hard that it didn’t make much odds whether he had his wipers on or off” (type 17).

I love parsing through Rob’s categories. Being a rain gazer myself (and rain, by the way, feels especially noticeable here in New York, where I live) …

The wonderful graphic designer T. Kyle MacMahon—known as “tkyle”—is especially good at capturing the joys of rain-gazing.
The wonderful graphic designer T. Kyle MacMahon—known as “tkyle”—is especially good at capturing the joys of rain-gazing.
GIF by tkyle

 

GIF by tkyle
GIF by “tkyle

… I couldn’t help but notice that something is missing from Rob’s list. He limits himself to one kind of rain—the kind that rains water, what you might call “raindrop rains.” But, in fact, there are other kinds.

In her book Rain: A Natural and Cultural History, Cynthia Barnett mentions Jonathan Swift’s fanciful metaphor “raining cats and dogs” (a coinage from 1738), but she then goes on to describe actual, unfanciful, documented rains of—and I kid you not—golf balls, fish, and, though I’ve heard about this before, frogs. As in, raining frogs (or toads).
Frog rain is shockingly normal.

Drip, Drop, Thunk

Barnett writes that in June 1954, Sylvia Mowday and her kids were in a park in Sutton Coldfield, just north of Birmingham, England, when it began to rain. They opened their umbrellas and were heading for shelter when all of a sudden they felt “gentle thuds” on their umbrella tops, “too soft for hail.” When they looked, they saw tiny frogs, “wee bodies” falling from the sky.

Maybe that’s what you’re seeing in this video—posted from Knox County, Ohio, on June 11, 2012—which shows (after the filmmaker, “MrKoozzz,” focuses) teeny frogs, all facing the same way, after a rain. (Alternate explanation: Could they be migrating? Hopping from one pond to another? Nope, they arrived by rain, writes MrKoozzz. “That’s my story, and I’m sticking to it.”)

In 1873, Scientific American ran eyewitness accounts of a frog rain in Kansas City, Missouri. It happened again, Barnett writes, in 1901, in Minnesota. There are ancient accounts, medieval accounts, even battlefield stories. During a French/Austrian battle in 1794 …

“A hot afternoon was broken by such heavy showers that 150 soldiers had to abandon their trench as it filled with rainwater. In the middle of the storm, tiny toads began to pelt down and jump in all directions. When the rain let up, the soldiers discovered more toads in the folds of their three-cornered hats.”

Drawing by Robert Krulwich
Drawing by Robert Krulwich

Assuming that all these stories—or at least some of them—are true, how do hundreds of toads manage to get airborne? Little toads—teeny as they are, are much heavier than raindrops. “Modern meteorologists,” Barnett explains, believe that “tornadoes and waterspouts are the most likely culprits.” High winds, especially whirlwinds, pick up water, toads, frogs (fish, golf balls) and all, and whisk them across the sky for a little while, then lose speed and dump the contents on, for example, Sylvia Mowday and her kids.

(Though, Cynthia wonders, if a whirlwind can pull a frog up into the sky, where’s the algae, the other pond plants, the fish? Why didn’t the Mowdays get hit with pond scum? She doesn’t know.)

But frog rain happens. Maybe not as often as rain type 49 (“sharply slanting light drizzle”) or type 51 (“light to moderate drizzle freshening”) or a “dirty blatter battering,” but frogs have been falling from the skies often enough, long enough, that I think they’ve earned the right to be called precipitation.

It’s odd that Rain God Rob MacKenna would leave them out. But he’s a lesser deity. The Big Guy, as you may recall, was more frog-friendly. Just ask Pharaoh …


For the best, craziest, most over-the-top frog rain ever (particularly the slack-jawed look on Philip Seymour Hoffman’s startled face when giant toads begin falling from the sky into his brilliantly lit swimming pool), there is nothing better than Paul Thomas Anderson’s 1999 movie Magnolia. If you dare (and I suggest you do … but it’s pretty graphic …) take a look …

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Raindrops Keep Falling on My Head: A Mosquito’s Lament

This, in case you were wondering, is a mosquito.

Picture of a drawing of a mosquito
Drawing by Robert Krulwich
Drawing by Robert Krulwich

 
This is a raindrop.
 

Picture of a drawing of a blue raindrop
Drawing by Robert Krulwich
Drawing by Robert Krulwich

And here’s a puzzle. Raindrops aren’t mosquito friendly. If you’re a mosquito darting about on a rainy day, those drops zinging down at you can be, first of all, as big as you are, and, more dangerously, they’re denser. Water is heavy, so a single raindrop might have 50 times your mass, which means that if one hits you smack where it hurts (between your wings) …

Picture of a mosquito being hit by a drop of water
Photograph by Tim Nowack
Photograph by Tim Nowack

… you should flatten like a pancake. A study says a mosquito being hit by a raindrop is roughly the equivalent of a human being whacked by a school bus, the typical bus being about 50 times the mass of a person. And worse, when it’s raining hard, each mosquito should expect to get smacked, grazed, or shoved by a raindrop every 25 seconds. So rain should be dangerous to a mosquito. And yet (you probably haven’t looked, but trust me), when it’s raining those little pains in the neck are happily darting about in the air, getting banged—and they don’t seem to care. Raindrops, for some reason, don’t bother them.

Picture of a drawing of mosquitos flying through the air, dodging large blue raindrops
Drawing by Robert Krulwich
Drawing by Robert Krulwich

Why not? Why aren’t the mosquitoes getting smooshed?

How Mosquitoes Survive Raindrops

Well, in 2012 David Hu, a professor of mechanical engineering at Georgia Tech, became interested in this problem and decided to pelt some airborne laboratory mosquitoes with water droplets while filming them with a high-speed camera—4,000 to 6,000 frames a second instead of the usual 24. That way he could watch them in super slow motion and figure out what they’re doing when they’re out in the rain. He published his findings in a 2012 paper that I’m going to describe here in “executive summary” form. (His video, by the way, is waiting for you below, so you can see what he saw for yourself.)

What he found is that most of the time anopheles mosquitoes don’t play dodgeball with the raindrops. They do get hit but usually off center, on their long gangly legs, which splay out in six directions. The raindrop can set them rolling and pitching, but they recover quickly—within a hundredth of a second. But even in the worst case, where the mosquito gets slammed right between the wings—a dead-on collision, because the mosquito is so light compared to the heavy raindrop …

Picture of a drawing of a mosquito clinging onto a falling raindrop as it descends through the air
Drawing by Robert Krulwich
Drawing by Robert Krulwich

… it doesn’t offer much resistance, and the raindrop just barrels along with the mosquito suddenly on board as a passenger. Had the raindrop slammed into a bigger, slightly heavier animal, like a dragonfly, the raindrop would “feel” the collision and lose momentum. The raindrop might even break apart because of the impact, and force would transfer from the raindrop to the insect’s exoskeleton, rattling the animal to death.

But because our mosquito is oh-so-light, the raindrop moves on, unimpeded, and hardly any force is transferred. All that happens is that our mosquito is suddenly scooped up by the raindrop and finds itself hurtling toward the ground at a velocity of roughly nine meters per second, an acceleration which can’t be very comfortable, because it puts enormous pressure on the insect’s body, up to 300 gravities worth, says professor Hu.

Picture of a drawing of a mosquito inside a raindrop, falling through the air
Drawing by Robert Krulwich
Drawing by Robert Krulwich

300 Gs is a crazy amount of pressure. Eric Olsen, at his blog at Scientific American, says a jet pilot accelerating out of a loop-de-loop experiences “only about nine gravities (88/m/squared).” One imagines his cheeks all splayed, his face squishy, but hey, that’s a soft-skinned human. We’ve got mosquitoes here. Their heads are harder. They have exoskeletons. Sudden accelerations don’t hurt as much, but what mosquitoes should fear, what they do fear, are crash landings. The ground is a lot harder than a mosquito.

Picture of a drawing of a mosquito being squished by a large blue raindrop
Drawing by Robert Krulwich
Drawing by Robert Krulwich

So what a mosquito has to do is get off that raindrop as quickly as possible. And here comes the best part: In most direct hits, Hu and colleagues write, the insect is carried five to 20 body lengths downward, and then, rather gracefully—maybe helped by a dense layer of wax-coated, water-repellent hairs—gets up and “walks” to the side, then steps off into the air, almost like a schoolchild getting off of a bus (albeit a fast-moving bus hurtling toward its doom). It does this almost matter-of-factly, like it’s no big deal. A mosquito, Hu writes, “is always able to laterally separate itself from the drop and recover its flight.” Always. (Unless the raindrop hits them too close to the ground.) If you want to see this for yourself, take a look at Hu’s video.


Video by David Hu and Andrew Dickerson

The moral here, should we need one, is that if you’re a mosquito on a rainy day, the place to be is high off the ground, and if you’re a human who worries about mosquito safety (not a big group, I know), you can move on. They solved this one roughly 90 million years ago.

Picture of a drawing of a mosquito with its arm around a raindrop, as though they were friends
Drawing by Robert Krulwich
Drawing by Robert Krulwich