by Bob Berman
The last time up here I’d rented a plane, taken advantage of Chena’s snowy runway, and headed north past the nearby Arctic Circle to land at villages like Bettles, population twelve, that have no roads at all. When the frozen rivers melt, everything gets in and out by small plane. After I landed on the white-packed runway, pretending I was a bush pilot even though the real McCoys have nerves and guts totally out of my league, I located the single diner-type restaurant among the small hunkered-down cottages. All the patrons looked up from their meals. They kept staring; they don’t get many visitors. I was the entertainment. The women were flirty. The men were strangely silent and wide-eyed. Yet late winter is a fascinating time to come—better than summer, with its relentless clouds of mosquitoes and endless, sleep-inhibiting daylight, which means no possible chance to see the legendary lights. “March is the best month,” I’d heard the natives say repeatedly.
Chena offers basic wood cabins, dogsledding, and—the big draw—a natural hot spring that feeds a hot pond. You relax in the three-feet-deep, 102-degree water under the auroras while your hair freezes solid. Afterward, a thirty-minute trip in a tank-tread arctic vehicle resembling a giant bulldozer with an enclosed cabin on top takes you up and up, far from the hot springs and the cabins, to a flat region at the top of a mountain surrounded by distant, jagged, snow-covered peaks in all directions. You first put on all the warm clothes you own—two layers of long johns, pants and hoodie, the works, and follow this with an orange government-issue polar jumpsuit. It’s still bitter cold.
Last time I was here, when the temperature was minus thirty-five degrees Fahrenheit, I stepped outside with a cup of boiling water and tossed it in the air. The liquid made a loud tinkling, crackling sound and hit the ground as frozen pieces of ice. Tonight felt no warmer, though the thermometer registered a mild minus twenty degrees Fahrenheit.
At the summit, the northern lights not only filled the sky but also painted the snowy landscape green. For a hundred miles in all directions the pointy mountains glowed emerald. This was routine for the hot spring’s owners, who bravely took over what was a struggling state-owned enterprise in 2000. Tonight they stared at the waving jade curtains for the fiftieth time this season, once again standing mutely in awe. At least I think it was awe. It might simply have been too cold for small talk. Being in awe and being frozen produce similar behavior.
No one spoke while the aurora undulated. The blotches, rays, arcs, and curtains rustle leisurely, like draperies in some vast celestial kingdom. The changes resemble the mutation speed of low clouds on a summer day. Keep staring, and the movement is barely perceptible. Look away for a minute and then turn back, and the scene has been totally transformed. Here in central Alaska, observers often gaze from directly beneath those curtains so that their “folds” angle vertically up, converging like railroad tracks straight overhead. Blotches vanish and are replaced. Pink fringes come and go. The slow-mo choreography can’t be predicted.
But the unseen entity fashioning it, the wizard behind the auroral curtain, is anything but sluggish.
The drama begins with an epic blast of solar particles escaping the clutches of both the sun’s gravity and its magnetic field. It was physicist Gene Parker who first surmised, in the 1950s, that the sun, the nearest star to Earth, leaks a continuous stream of broken atom fragments—an outflow he called the solar wind. The reward for his prescience: people openly scoffed. It was only when spacecraft launched after 1957 actually detected this nonstop swarm of material—about ten particles for each sugar-cube volume of space, all hurtling outward at a few hundred miles a second—that Parker went from goat to prophet.
Accompanying his promotion came a slow recognition of the ways in which the sun’s wind has been affecting our solar system all along. Soon everyone, with the groupie wisdom of hindsight, said, “Of course! That must be why comets’ tails always point away from the sun. Comets are like wind socks. They’re blown back by the solar wind. We should have known!”
It took until the 1970s, however, before researchers discovered the truly superdense, superspeedy solar winds that make Parker’s solar wind seem by comparison a mere zephyr. These explosions blast away ten billion tons of material at a time at five hundred miles a second. Called CMEs, or coronal mass ejections, they are the real deal and can inflict serious damage on our electrical grid and satellites.
That’s the rough motion picture of the sun’s particle geysers. But, as always, the devil is in the details. Our planet’s magnetosphere can direct those shotgun pellets of solar detritus safely around and past our world, but only if the swarm’s field and our planet’s field share the same magnetic polarity—if, for example, both fields have their norths aimed upward. As they say in magnetic gossip circles, “Like repels like.”
Though their motion is imperceptible to the eye, these Alaskan glaciers typically advance toward the sea at the speed of a foot per hour.
Conversely, if the buzzing swarm of solar hornets has a polarity aligned opposite ours, it will transfer its energy to our planet’s field. Then the charged particles slither angrily down our magnetic field and into our upper atmosphere. This creates huge electrical charges. Oxygen atoms in the thin air one hundred miles above us have their electrons excited. They emit an alien green glow as these electrons fall back into their preferred, accustomed positions. That’s the entire aurora story.
The whole thing is a motion demo. Sun material in motion. Our own air’s electrons in motion. The aurora itself, like living abstract art, in vivid, fabulous motion—even if it takes a minute before the scene has completely transformed itself.
What’s surprising is how few people in Alaska understand the process even in a general way. They look up routinely at the lights, but I’ve overheard many “explain” to their companions that it’s sunlight reflected off the oceans from the bright side of Earth or deliver some similarly discredited nineteenth-century elucidation.
Apparently, like Gene Parker’s supersonic solar wind, science knowledge has its own motion. And this, as in the old days of Jack London and his Inuit fantasy tales, sometimes moves with all the alacrity of Alaska’s blue ice.
CHAPTER 7: April’s Hidden Mysteries
Deciphering the Secrets of Spring
(but
true
to the incomparable
couch of death thy
rhythmic
lover
thou answerest
them only with
spring)
—E. E. CUMMINGS, “O SWEET SPONTANEOUS” (1920)
It was April, after a warm winter. A million-ring circus erupted in the mountains of the Northeast, the calendar thrown out the window. Bees circled wildly around neon-yellow forsythia, weeks ahead of schedule. At the renowned Cornell University Cooperative Extension, top botany, zoology, and entomology experts scratched their heads, helping local farmers figure out how such early springs affect apple trees and such.
Even after a normal northern winter, with its unchanging monochrome, the noun spring doubles as a verb. Countless actions spring to life. They set children’s minds going: How fast do flowers open? Trees grow? Insects fly? Saps flow? How does it all happen?
Mere recitations of speed data wouldn’t do justice to the whole choreographed enterprise. Not when colorful complexity pops everywhere like jack-in-the-boxes, spurred by sun and warmth. For biology is really the friendly face of physics. As temperature increases, so do all the enzymatic, mitochondrial, glucose-transfer, and other reactions upon which life is based.1 We mammals make our own heat, and when that’s too difficult we hibernate, drop our body thermometers by ten degrees or so, and wait it out. During hibernation a chipmunk’s heartbeat slows from 350 beats per minute to as little as four. The pace of activity—within bodies and around them—becomes glacial, as a sleeping community of bears, bats, ground squirrels, and woodchucks snore unseen, often much nearer to our bedrooms than we imagine.
But plants and invertebrates can’t do this. They nee
d winter to end. So when it does, and when they—meaning insects, worms, tadpoles, and the like—emerge, so do their predators: birds, raccoons, and foxes. The whole awesome production materializes together. That’s why spring isn’t just a season. It’s a motion-based event.2
In subtropical Florida, Southern California, and Texas, spring begins in February and moves one hundred miles north each week. Air travelers observe its vivid border as opening blossoms and leaves rush poleward at the speed of one kilometer, or 0.6 miles, per hour. Spring travels about the same rate as a parent pushing a stroller.
Over the course of three months, spring proceeds more than a thousand miles to envelop all of Maine, North Dakota, Montana, and Washington State as well as parts of southern Canada. In mountainous regions it sweeps first through the valleys and then climbs ever higher up the hills.
Plants bloom in the same sequence year after year. The earliest—snowdrops and crocuses—pop up where the snow has barely melted. They’re soon followed by bulbs, such as tulips and daffodils. At that point the changes are measured in days, with the arrival of the bright yellow forsythia bushes. And then the first tree buds and baby leaves burst forth from the impatient chartreuse performers, such as willows, magnolias, maples, and rhododendrons. Cherry blossoms appear around this time, too.
Insects emerge from their winter dormitories. Like plants, they do not wait for a particular date but respond to warmer temperatures. Some, like butterflies, go through the full spectrum of life stages in tree hollows and crevices during the winter—larvae, eggs, and adults—so that they can hit the ground running in the spring. Migrating aviators, such as robins and red-winged blackbirds, arrive earliest to get in on this first action. They catch the initial emerging insects and worms after using the same flyways they traveled in the autumn, when they went south. Now they lay claim to their breeding and feeding territories.
Insect development only occurs when the temperature rises above a particular threshold, which is often fifty degrees. Once it gets warm enough, it almost seems as if spontaneous generation is at play: they’re suddenly everywhere. Ants start walking, at an average speed of one-fifth of a mile per hour. (By contrast, thunder covers that same one-fifth of a mile in a second, making thunder 3,600 times faster than ants.)
Each species has its own story and public relations image. Everyone loves butterflies, which boast mellifluous names in all Romance languages: papillon in French; mariposa in Spanish. Even German manages to make butterfly a bit less guttural than usual: der Schmetterling. Bees and dragonflies get good press, too.
But not mosquitoes, of course. They come in some 3,500 known species—new ones are still being identified—and have been called the most deadly creatures on earth, thanks mostly to the three varieties that carry the diseases malaria, dengue, and yellow fever. Only the females suck blood from vertebrates such as ourselves.
Movement plays a key role in our mosquito experience. They need standing water and rarely venture more than a mile from their breeding ground. So if you control the stagnant pools of water in your area (meaning no old tires, sagging tarps, and the like) you may be able to completely prevent their appearance. In deeply wooded places, such as Maine and especially Alaska, where small nooks, ponds, and saturated soil left over from rain, melted snow, and permafrost are virtually everywhere, it’s a hopeless cause.
Mosquitoes live everywhere on earth except Antarctica and can be so thickly ubiquitous that each member of an Alaskan caribou herd typically loses a pint of blood a day. Despite mosquitoes’ prevalence, males only live a week; females a month at best. Their egg, pupa, and larva stages together last just a couple of weeks. So if and when breeding grounds dry up, mosquitoes vanish a month later.
Frustrated at trying to swat them? Scientists who study insect speeds conclude that they seem faster than they really are. This perception issue harks back to that old business of how many body lengths something moves per second. Mosquitoes most often fly at 2.5 miles an hour, so they can’t even keep pace with a jogger. But since this translates into 170 mosquito body lengths per second, they may seem supersonic.
Bees routinely move at jogger speed—seven miles per hour. Of the emerging springtime insects, flies, which look the fastest, are the fastest, at ten miles per hour. Of these, the horsefly is the champ, as everyone knows who has tried to dodge those creatures from hell. They can fly at 14.8 miles per hour, so only fast sprinters can hope to outrun them. The very quickest insects, however, are the good-guy dragonflies, which appear in 5,680 species and have been clocked at an amazing forty miles per hour. Best of all, they love to eat mosquitoes and have the velocity to catch them effortlessly.
May is when the flower petals of rhododendrons and azaleas add their color, along with crabapple trees and flowering dogwoods, Cornus florida. Also in May, wisteria blooms, accompanied soon thereafter by the magical lilacs—or at least the most cultivated variety of lilacs, Syringa vulgaris. Their heavenly scent, following the magnolias by a couple of weeks, fills the countryside.
Aromas themselves have their own tricky motion, since they can only move with air. Dead calm means that scents scarcely migrate from blossoms. On the other hand, too brisk a wind, and their molecules are diluted and whisked away.
It is still officially spring in early June, when perennials explode almost in unison, along with flowering shrubs such as bridal wreaths and roses and viburnums. The early frenzy is now replaced with the steady rhythms of shrubs, flowers, and trees destined to peak at their own predetermined periods. By the time spring ends, at the June 21 solstice—which is more frequently happening on June 20 as this century progresses, one result of the four-hundred-year Gregorian calendar cycle—the final holdouts, such as hickories and the slowpoke catalpas, have come into leaf even in their northernmost ranges.
This dynamic simultaneous animation of millions of insects, plants, and animals within a hundred yards of your rural home repeats every spring in the same sequence. But now look closer, to the motions hidden behind the curtain.
In 1663, the British philosopher and natural scientist Robert Boyle wrote, “There is in some parts of New England a kind of tree… whose juice that weeps out of its incisions, if it be permitted slowly to exhale away the superfluous moisture, doth congeal into a sweet and saccharin substance.” So indeed, one heralded early-spring marker in the northern states is the tapping of maples for the purpose of collecting sap, which is then boiled down for syrup. Since it takes forty gallons of sap to produce a single gallon of maple syrup, copious fluid is required. Many people imagine that all trees have sap running in them during the spring, but it isn’t true. Very few emit sap when punctured, and the maples do so only under odd conditions—and only before they come into leaf.
Maples produce sap during periods of cold nights and warm days, a situation that occurs most often in March and April. Sap flow stops if the temperature is either continuously above or below freezing and when the nights no longer fall below freezing. It’s very odd behavior. You can tap willow, ash, elm, aspen, oak, and many others and you’ll never collect a drop of sap. We now know that the reason has to do with freezing inside the tree and then the subsequent warming. This releases expanding gases that push the fluid. And yet no one understands why a sweet, sucrose-filled liquid is necessary or what this has to do with living tree cells. So it’s still largely mysterious, though syrup’s gooey, ambrosial presence on pancakes temporarily erases any frustrations we might have with science.
By contrast, other trees have saps running upward through their xylems when they are in leaf, and it is not sweet. Plants and trees transpire, meaning water evaporates from their leaves. This creates a partial vacuum that pulls water up from the roots. You’d think the sap would run fastest on hot afternoons, since plants transpire three times faster at eighty-eight degrees than they do at seventy degrees. But sap speed is fastest in midmorning, even if it continues all day.
Superman’s X-ray vision would observe that sap is no slowpoke. For years
, measurements have been attempted by means of injected dyes and radioactive monitoring, but the past decade’s favored method involves thin temperature probes inserted into the tree in various places and the introduction of heat at the trees’ bottoms. These show that the rising sap carries the introduced heat upward at rates as fast as one-third of an inch per second. This may not sound fast, but it translates into ninety feet an hour, letting even the tallest trees quickly deliver water from roots to leaves. Most trees are not so speedy, however, with figures closer to eight feet per hour—still sprightly enough for us to see water motion if we could peer through the bark.
In the deep woods, meanwhile, wildflowers push their shoots above ground to take advantage of the preciously brief period of forest-floor sunlight before tree leaves shade them.
As the thermometer climbs, so does the noise level, for sound is the auditory manifestation of movement. A familiar example of this is the chirping of crickets. Only male crickets stridulate, but what’s obvious in every rural zip code is that the pace changes with the temperature. The chirping sound, which comes from the top of one wing being scraped along the bottom of the other, gets more frenetic on warmer nights.
Once again, it’s the same principle as an old battery failing to start the car on an icy morning. Chemical reactions speed up as temperature increases, as do the metabolic processes in insects, which is why it’s always wisest to dislodge an unwanted hornets’ nest on a frigid night, when they are too cold to respond. Ants, too, walk at a speed that depends on the temperature. All insects rely on myriad chemical reactions in their bodies and have no way to speed them up except to hope for an environmental warm spell. As the temperature rises, they more easily reach the energy threshold necessary for chemical reactions that will let them perform various muscle contractions, a prerequisite for walking, flying, or—in the case of crickets—chirping.