Tying Down the Wind takes readers on a voyage of discovery through the atmosphere, a swirling ocean of air that surrounds and sustains life. The journey begins in a sunny New England woodlot and ends atop the polar ice of Antarctica—where we learn, remarkably, that the two extremes are not so different.
What triggers changes in the weather? How are tornadoes, thunderstorms, heat waves, and blizzards all related? Tying Down the Wind supplies the answers, and invites you to experience the excitement of the world’s worst weather in the comfort of your own home...or car.
Drawing on the author’s experiences at the Mount Washington Observatory in New Hampshire’s White Mountains, Tying Down the Wind revisits the devastating Northeast Ice Storm of 1998, takes readers on a snow-blind walk through a Berkshire blizzard, and describes the impact of a 54,000-
degree lightning bolt just a few yards away.
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About the Author
Read an Excerpt
I am grateful to all of the meteorologists, technicians, mountain guides, educators, and friends who offered comments and suggestions during the years in which this book was being written.
Sarah Curtis, Dave Thurlow, Mark Ross-Parent, Gloria Hutchings, Lynne Host, Dar Gibson, and Jacob Klee freely shared their insights and anecdotes about mountains, Antarctica, and weather in general. Without their contributions, this book would have been much more difficult to write and much less entertaining to read.
For hospitality, humor, and inspiration, I’m indebted to the entire crew of the Mount Washington Observatory, past and present. For years of support and encouragement, I owe thanks to my parents, Richard and Jane Pinder, as well as to Sarah Shor, Tim Ewald, Steve Piotrow, and Meredith Piotrow. Special thanks also are due to Mitch Horowitz at Tarcher Putnam, Barbara Shor, Susan Ross-Parent, Britt Scharringhausen, Jennifer Morin, and many others who read drafts of the manuscript and provided valuable feedback and constructive criticism. Most of all I wish to thank my agent, Laura Langlie, for her advice and enthusiasm.
MARK TWAIN ALWAYS HAD PLENTY TO SAY ABOUT THE weather, particularly New England weather. “Cold!” he once wrote. “If the thermometer had been an inch longer we’d all have frozen to death.”
Perhaps his most famous quotation is a phrase he borrowed from Charles Dudley Warner, a Hartford, Connecticut, newspaper editor, in 1897: “Everybody talks about the weather, but nobody does anything about it.”
Twain wasn’t the only one who thought that way. An old joke still making the rounds in the North Country (which humorist Bill Bryson recalls in A Walk in the Woods) is about how winter seems nine months long, and is followed by “three months of not-so-good sledding.”
I’ve lived in the Northeast all my life, through heat waves and blizzards, thunderstorms and freezing rain, so I’m no stranger to the vagaries of weather. But even as a child I always wanted to know more. In answer to Mr. Sam Clemens’ complaint, I didn’t want just to talk about the weather—I wanted to do something about it.
“What is wind?” is a question I first asked myself—with the intention of writing about it—while walking through a woody corner of Massachusetts on a frosty autumn evening at the age of 24, listening to invisible breezes sift and surge through the pine branches. This book is the end result of my attempt to find the answer.
IN THE SPRING of 1995, I left Massachusetts and seized an opportunity to investigate the wind like never before. Where better to study the science of meteorology than on a rime-encrusted mountaintop at an observatory devoted specifically to that purpose? So I journeyed to a summit where the wind never stops howling and snow falls in July.
My intention was to stay for only a season (the “not-so-good sledding” one, which most people call summer). Little did I know that for years to come I would live there—and once almost die there.
Something in the wind gripped my imagination and refused to let go.
An Ocean of Air
Born in the Belly of the Sun
“IT WON’T BE LONG BEFORE YOU GET HAMMERED BY A hundred-mile-an-hour blast,” meteorologist Mark Ross-Parent shouted, cupping his hands to his mouth like a megaphone. His thick, reddish-blond beard bristled in the wind. “My first week here we had a peak gust of one-sixty!”
I barely heard him. A sudden gust of wind made me stagger back and trip over a metal grate. Mark’s mouth formed another string of syllables, but they were muffled by the growl of the air. “What?” I hollered back at him. He spoke again. Whatever words he uttered slipped away in the wind long before they reached my ears.
“What?” I roared back a second time.
Mark yelled, almost screamed, and I finally heard a whisper siphoned through the gale. “I said ‘watch your step!’” He carefully enunciated each word.
The two of us were standing—or trying to stand—in sustained gale-force winds on top of Mount Washington, New Hampshire. The land around us crested and dipped with blue and brown mountains, fading on the horizon at the limits of vision. It was a cold, blustery May morning in 1995 (or so I remember thinking. A few months of acclimatization would soon alter my perspective). Sixty-one years earlier on that very spot the strongest wind ever measured on Earth—231 mph—shrieked across the summit. Three excited meteorologists had witnessed the event, and had escaped with minor injuries, a deep respect for the destructive power of wind, and a tale they would tell proudly all their lives.
Ever since that day, technicians at the meteorological observatory had continuously documented the extremes of weather. Mark and I were among them; our job was to watch the sky—and sometimes just to watch out!
On that brisk afternoon, we were dressed in coats, wool hats, and gloves. Mark, showing his rebellious side, wore short pants. It was almost summer, after all. He gripped the railing of the watch deck and braced against the powerful impact of quintillions of air molecules against his chest. The hood of his jacket started to snap back and forth in the wind. He has a short, stocky, strong frame—the perfect build for a weather observer at one of the windiest locations in the world. Tall people soon learned either to stay indoors or else resign themselves to the inevitable scrapes and bruises from being batted around by the paw of the wind.
I had just started my new job as a weather observer and already had a sore elbow to show for it; an unexpected gust had slammed me against the metal door. I still had a lot to learn.
Mark was showing me the ropes. Or rather, the lack of ropes. “When the wind’s really blowing, they’d just whip around and hurt you. Or you’d get all tangled up.” I took his meaning: in a hurricane-force wind, hold on tight and don’t let go.
A few bright patches of rime ice decorated the wind-scoured summit cone. The high albedo, or reflectivity, of the white ice crystals bounced some 90 percent of the sun’s incoming energy back into space. On the limited surface area of a mountaintop, the effect was minimal—the snow and ice patches were exposed and vulnerable to any sharp increase in temperature. A river of air, thousands of miles long, poured constantly over the peak, but the individual air molecules in that swift stream were scarcely affected by their brief contact with the alpine ice and snow. However, in places and times that the snow cover was more extensive—like the long winter of the last ice age—a different story unfolded. The white, icy surface radiated away longwave energy—heat—exceptionally well. It also reflected shorter wavelengths of light, including ultraviolet (UV) rays, which otherwise would have contributed to warming the ground. In this way, the ice perpetuated itself. The white surface continued to keep the air cool by nullifying the warmth of the sun. (In modern times, the same process helps produce bitterly cold nights across North America each winter, whenever there is no cloud cover to “trap” the radiated heat.) Only a climate shift, or the sudden arrival of a warm air mass from beyond the horizon, could break the cycle.
Cycles and change—that was what weather was all about. I had come here to study weather at its worst in the hopes of understanding weather at its best. My firm belief was that no matter how severe the weather, the underlying rules it follows always stay the same and are, to a degree, predictable. Over the next several years, I planned to put that theory to the test.
Any good science book can tell you how the sun heats Earth more in some places and less in others; in doing so it creates weather. Probe deeper into the science of meteorology and you may learn how the sun makes cotton-ball cumulus clouds materialize in a blue sky—and how it heaves the 20-billion-ton bulk of a hurricane from the surface of a tropical sea. But there are certain things that you cannot learn from a textbook.
I was not satisfied parroting old equations and standard schoolroom explanations. Ever since childhood, when an unexpected lightning strike blasted apart an oak tree outside my bedroom window and the house shook with thunder, I had felt an urge to understand the hidden forces of weather. I wanted to comprehend fully—to feel in my gut—how the sun was responsible not just for warmth, but also for bitter cold. For example, the icy wind howling at that instant over Mount Washington and past my ears.
In taking this job at the observatory, I hoped to go beyond a mere textbook knowledge of the mathematical intricacies of weather. I needed to acquire some hands-on experience. Literally. Given the absence of safety lines, it quickly appeared I would not be disappointed.
My task at that moment was to take a weather observation for the National Weather Service. Cloud cover, cloud height, visibility, temperature, dew point, and half a dozen other statistics were measured and written down in SA (Surface Airways) code—later changed to METAR* code—every hour, then transmitted via modem to weather service headquarters in Bismark, North Dakota. Thousands of other stations—from sunny California all the way to Antarctica—repeated the procedure, feeding endless data into massive computers in order to determine regional forecasts, thunderstorm potential, short- and long-term climate indications, and even the evidence for a possible global warming trend. The weather station on Mount Washington was just one small but intriguing piece of the bigger picture.
As I walked across the summit cone, stratocumulus clouds billowed below me, threatening to engulf the summit in fog. A glance at the sling psychrometer in my hand told me the temperature had dropped to 35 degrees Fahrenheit. Factoring in the wind speed, the apparent temperature plunged to minus-2. The expression on Mark’s face—he was gritting his teeth—told me that he had started to regret his choice of attire. With a wave of his hand—we could no longer hear each other at all over the howl of the wind—he indicated that he would meet me back in the office. I continued to scan the sky.
The sling psychrometer I held was a device used to measure moisture in the atmosphere. It contained a dry-bulb thermometer, which provided the temperature of the air, plus a second thermometer wrapped in a wet wick. The evaporation of moisture off the wick cooled the thermometer, to the point at which no more water could evaporate. The difference between the two instrument readings let me establish the dew point and relative humidity.
Weather is ultimately about the transfer of latent and potential energy via wind and water. (Energy in the atmosphere mostly comes from the sun—but not entirely, as I would soon discover.) The evaporation of water requires an input of energy, or heat, to boost each molecule from the slower liquid phase to a more active gaseous state. It takes 540 calories of energy to evaporate a single gram of water. Whenever a water molecule jumps phase, it “robs” a little energy from the surrounding atmosphere. The air cools. The larger the number of molecules evaporating, the greater the drop in temperature. That explains the cool breezes I had so often felt immediately after summer showers—the rainwater was in the process of evaporating even as it fell from the clouds, and on the ground it continued to change into gas. Both evaporation and condensation are always occurring on and above any liquid water—including a raindrop—but the temperature and pressure determine which process is predominant.
On the mountaintop, the wet wick of the psychrometer in my hand operated on the same principle. Water molecules always evaporate faster and in greater quantity in a warm, dry air mass than a cold, moist one. So as molecules disappeared off the wet wick, more and more heat was transferred—“removed”—from the air; the mercury dipped. By determining exactly how far it had fallen and comparing that number to the ambient temperature, I successfully measured the moisture in the sky.
The result did not surprise me. The stratocumulus clouds so close to the summit hinted at the arrival of a humid air mass. Now I had the actual numbers. Relative humidity had climbed to over 85 percent. The dew point—the temperature at which water vapor in an air mass must condense into fog at a given atmospheric pressure—had been rising all afternoon and now stood at 31 degrees, only a few degrees lower than the actual air temperature. Once the two numbers met, the air would be saturated and a blinding mist would appear. So I didn’t expect our view of the sky to last very long, and I was not disappointed. Only a few hours later the air thickened into a soupy blur, cutting off the visibility at 100 feet. The sun dimmed and disappeared behind a screen of fog.
That first week on the mountain fascinated me but taught me nothing new about wind and fog. Less than six months later, however, a deadly mountain blizzard would change my perspective forever.
FIRE, AIR, WATER, and earth are the four elements of nature, according to the ancient Greek philosophers. Coincidentally, those few simple words spell out all the vital ingredients in a recipe for weather. A snowflake, a raindrop, a cloud, a tuft of fog, and a soft gust of wind contain a little of all four.
Fire is the element that binds the others together—and, on occasion, rips them apart with a fury unmatched by any lesser force of nature. Since my goal is to explain the hows and whys of weather, I had better start at the beginning—with fire.
More than five years have now passed since I first stood on this mountain and was introduced to the savage wind by Mark Ross-Parent. In that time, I have dodged bullet-sized hailstones in 70-mph gusts, flinched as a hurricane splashed ocean spray against my face, and waded neck-deep through a cloud. Yet I am still awed by the mysterious cyces, loops and swirls that tie the disparate forces of weather into one comprehensive whole.
The sun, of course, is the key.
This afternoon I have scrambled on foot up the mountain to the observatory, arriving on the summit just in time to witness the daily death of the sun. Once each day the furnace of the yellow star effectively switches on and off, alternately heating and cooling half the Earth. That’s simple enough. But the method in which it channels weather from place to place takes a lifetime of learning to understand.
As I watch, the life-giving daystar melts and boils on the horizon. The clouds above me are aflame. At this altitude, the sun seems close enough to touch. Like Icarus, who miscalculated the melting point of wax, I start to worry that I have come too close. It is a long way to fall, standing here eye-to-eye with the unblinking sun. But the view!
When I arrive on the peak, a mattress of billowing cumulus clouds floats above the green forest of New Hampshire, kept aloft by a cushion of warm, rising air. Stratocumulus clouds tumble across the sky at an altitude of 4,000 feet—just tall enough for a pair of snowcapped hills to jut like bedposts from the base of the gathering fog.
Overhead, separated from lower clouds by a mile of crisp, clear air, a thin sheet of altostratus flutters in the westerly breeze. Slowly, the higher clouds press down, settling like a blanket atop the cumulus. The sun is squeezed between these two layers. Already low on the horizon, ready to turn in for the night, it sends out a final burst of red rays.
A flickering prairie fire consumes the sky. The clouds broil, a sudden kaleidoscope of red and orange.
Tongues of fire singe the horizon from pole to pole. The sunset becomes a fiery tsunami, flooding the altostratus with orange, and leaving only the black coal of night in its wake. The clouds lunge down and snuff out the flames. In seconds, what little remains of the sunset is doused, and the summit sits snug in the mist of twilight.
TWILIGHT IS A lonely time. The owl, a night dweller, props open her dewy eyes but hesitates to spread her wings and fly. The sunshine is not quite ready to retire; it still flickers awhile below the hills.
As I walk back down from the summit of the mountain, I feel the wind hesitate. It is not quite awake, not ready to stir.
Ghost-like tufts of fog slink across the stones. Their feet sliding silently from rock to rock, these apparitions step lightly on a cushion of air, baffled by my presence here among the clouds. A mountaintop at twilight is no place for the living.
In 1846, philosopher Henry David Thoreau climbed a mountain and stood “deep within the hostile ranks of clouds.” He was alone. “It was like sitting in a chimney and waiting for the smoke to blow away,” he wrote in his journal.
I sit down to rest on an ice-crusted boulder. Am I the only warm-blooded creature above tree line, a single man in a nest of ghouls? So it seems. The air is empty, blowing cold silence across the boulders.
If I sit still, the ghosts ignore me and continue their march up the mountain. The last ghost in line tugs a ribbon of wind behind him. Sometimes the ribbon slips free from his grip and lashes out, rustling my hair, stirring the cold sedges from their sleep.
“What are you doing here?” the wind whispers. It has spotted me, an unwelcome anomaly in a sleepy world. Then the wind stills, silent, waiting for a reply.
The low sun, filtered through the fog, casts an eerie glow on grasses and stones. It is as if the ground were covered with a fine dust of orange pollen.
Tundra grass, brittle as dry straw, rustles and hisses in harmony with the wind. Autumn is here, and the alpine garden quivers with cold.
I can feel wind tug at my sleeve with unseen hands. When I look for the sun, all that is left is a dying red spray filtering through the trees. For a moment, the fog thins. Stars poke holes through the dark canopy of the evening sky. The air stiffens and chills.
BY CLIMBING THIS mountain I bring myself physically closer to the sun. But a vast chasm still hangs between me and the answers for which I am searching.
All mountains interrupt the relative flatness of Earth’s topography; they provoke weather systems to rise and flow in unexpected ways. Orographic lifting forces air to climb and cool adiabatically, abruptly changing the ratio of evaporation to condensation so that a thick fog appears. In simple words, the mountains wring the clouds dry.
Aristotle got this much right. In his often erroneous book Meteorologica, from which the science of meteorology gets its name, he states: “. . . mountains and high places act like a thick sponge overhanging the earth and make the water drip through and run together in small quantities in many places.”
On distant Mount Rainier, in Washington State, a thousand inches of snow have fallen in a single season, only a short hop—geographically speaking—from a parched, moistureless desert. The dichotomy of a cold, moist climate nestled snugly in the same corner of the map as a hot, dry climate still amazes me. How can that be? Here on Mount Washington, more than five hundred inches of crystalline ice blanketed the peak one winter, while the valley at its base only a few miles away received a tiny fraction of that amount.
This mountain where I monitor the weather is called Agiocochook, “Home of the Great Spirit,” in the language of the Abenaki Indians. It is a 400-million-year-old wedge of metamorphic rock thrust abruptly into the sky. “Killer Mountain” is how one book describes this peak. “Home of the World’s Worst Weather,” boasts another nickname.
Like any mountain, Agiocochook offers weather watchers a stepping stone to the clouds. The summit is a natural laboratory, a platform on which to study the ocean of air that thinly surrounds and protects the globe.
It is also a convenient place to study the sun. The shield of air we call the atmosphere is 18 percent thinner here than at sea level. We are that much closer to the unprotected vacuum of space, to the seemingly empty abyss through which the sun’s rays and the solar wind fly unimpeded. Sensitive instruments detect the flux of solar energy as it intersects Earth.
Aristotle correctly asserted in 340 B.C. that there can be no weather without the sun’s fire. Of course, he and his contemporaries also got a few things wrong. In one misbegotten book of scientific blunders derived from the dogma of ancient Greece, I remember seeing an unusual theory that made me smile. It claimed that the wind is set in motion by leafy tree branches that bend and sway under their own power, waving the still air like a fan. Why else does the atmosphere swirl and sigh, the ancients pondered, unless propelled by a push from supernaturally animated sticks of wood?
Unfortunately, the unknown author never explained to anyone’s satisfaction the mysterious power that makes trees move in the first place. Wiser and better-educated generations laughed at the theory, then discarded it. But Aristotle and his contemporaries still had a point. Even if their answers failed to survive the scientific advances of two dozen centuries, their questions hit the mark today.
Once we know the hows and whys of the gusty movement of air molecules across the sky, once we can explain the clockwise swirl of sinking air around a high-pressure area on a cool, sunny day, a single unanswered question remains: What is it that first stirs the wind—what starts it going?
Wind is the power of our atmosphere in action, the invisible but always driving force behind the beauty of nature. Cold fronts punch through the lower troposphere—the lowest, densest layer of the sky—powered by bitter northwest winds. Warm fronts glide gently over ridges of cooler air, bringing soft rain that lasts hours or days.
But the wind has no earthly origin. Forget the swift push of air that makes a flag snap against its pole. Pay no heed to the breeze that provides lift for the wings of birds, or the howling, moisture-laden gales of the sea that carry pollen and life from one continent to another. Despite the wind’s obvious impact on our planet’s biosphere, its story is set in motion far, far away.
If we seek to discover the true origin of wind, we must first shrug off the comfortable embrace of Earth’s atmosphere. The trek will take us through the vacuum of space, beyond the orbit of the airless moon. We must streak millions of miles past the sulfurous skies of Venus, inward toward the craterous dust of Mercury as it bakes near the sun. Soon, we find ourselves plunging toward the gravity well of a blazing star. We must shield our faces from the heat and willfully dive into gaseous flames far too hot to liquefy. They undulate across the outer shell of this middle-aged star as it drifts silently through space along the cold, dark edge of a spiraling arm of the Milky Way.
Even then, our journey is not over. In a quest to locate the origin of wind, we must sink deeper into the thermonuclear core. For the wind on Earth is born in the belly of the sun.
The sun is an atmosphere so massive that its own weight has set it ablaze. It is a 27-million-degree inferno, hot enough to smash hydrogen molecules together at unimaginable speeds until a new element—helium—emerges from the flames. Nuclear fusion powers the sun. It feeds on itself like an undying coal, consuming the binding energy of atoms for fuel. The sun’s kiln is a medieval alchemist’s dream.
Our sun is a star, all but immortal in human terms, gobbling up the passing millennia like kindling. Knock tiny Earth loose from a stable orbit and hurl it into this giant furnace and it will disappear like an ice cube dunked in boiling water. The cold Atlantic and the deep bowl of the Pacific will evaporate in half a second. The North Pole’s ice cap will shrivel and wink out of existence—a white hat whisked away in a fiery breeze. Rocks and mountains will melt into lava. Continents will turn to slag and dissolve.
And yet, at a safe distance of 93 million miles from Earth, the sun nourishes life. Its caress gently warms the rocks and stirs the breeze. Heat is radiant energy; it jump-starts the motion of air. It supplies the oomph to change water from solid to liquid to gas. Trees sway, animated by the breeze, and not the other way around. Liquid dew evaporates off grass stems and adds moisture to the sky. Cumulus clouds surge upward to cap a pleasant day; high cirrus clouds redden the horizon at dawn and dusk, heralding the weather of tomorrow to the watchful eye.
WIND IS A tool used by nature in a hopeless pursuit of equilibrium. The sun upsets the balance. Except for negligible amounts of heat generated by the molten core in the interior of Earth, by radioactive decay, by the pull and tug of the tide, and by a secondary radiation emitted from the atmosphere, the sun is the source of all heat and energy on Earth. In a single day, sunshine intercepted by our planet provides the equivalent of 700 billion tons of burning coal. And that is only a small fraction of the sun’s total energy output.
But there is a problem. The sun does not distribute its warmth evenly. Dark mud absorbs heat far better than does a snow-covered field, which with its high albedo bounces away the sunlight and stays frigid. Already a disparity emerges; the surface of the planet heats and cools in patches. The equator basks in plentiful sunlight while the poles are refrigerated. Air masses expand or contract in different locales. To complicate matters, Earth’s swift rotation creates a series of concentric rings at different latitudes, each spinning through the cycle of day and night—warm and cold—at a different speed. Meteorological charts depicting temperature and atmospheric pressure jump up or fall down chaotically depending on time and location. It is up to the wind to smooth out the bumps.
The wind never succeeds. Never.
If a small parcel of air is heated by direct sunlight, the molecules absorb the energy and expand to fill a greater volume. The air becomes lighter and more buoyant; it quickly rises through the cooler, denser air surrounding it, leaving a near-vacuum in its wake. But nature abhors a vacuum. (Aristotle got that right, too.) More air rushes in from all sides to fill the hole. Wind starts to flow.
I can see this process illustrated perfectly on the mountain slope below me. Much of the ground is covered by a lingering snow, but I notice a solitary shelf of smooth, dark rock. The sun bakes down on that shelf, which heats the air above it like a stovetop burner. A thermal is created, a river of warm air rising vertically into the sky.
A second small air mass—a cooler one—slides horizontally off an adjacent snow patch to replace the air that is rising. In time, it too will warm on the rocks and start to rise. But even before that can happen, a third air mass blows onto the vacant snow patch abandoned by the second air mass. And then a fourth parcel of air from a more distant snow patch drifts over to take its place. By heating that one small shelf of rock with its low albedo, the sun has set in motion a chain reaction. Air gusts from place to place, trying to equalize the constantly changing atmospheric pressure. I imagine the repercussions of that thermal over Mount Washington rippling from here all the way to Mount Everest and beyond. The wind never stops, not as long as the sun shines.
AIR IS NOT solid but a gas and therefore breathable, a blessing we owe to the sun. The sun replenishes the sky with heat on a daily basis. Without such a regular downpour of radiant energy, the polar ice caps would grope around the globe with icy paws until at last they touched and clamped together. In the embrace of perpetual winter, life would first retreat to a perilously thin band of warmth at the equator, until crushed at last beneath the weight of glaciers.
Snuff out the sun like a candle and Earth’s own inner heat will quickly prove inadequate. Oxygen liquefies at 297 degrees below zero Fahrenheit. Air yields to solid ice at minus-360, a point at which both oxygen and nitrogen crystallize and collapse, tumbling from the sky like snow.* The 400-mile-thick atmosphere quickly compresses, accordion-like, into a thin, deadly frost on Earth’s now bitterly cold surface.
As the atmosphere dwindles, the wind withers. The oceans freeze solid. First a thin white sheet will appear on the surface; then waves will petrify, stiff and motionless like a snapshot. Ever deeper the ice presses and grows down into the murk where eyeless fish swim in a panic. A few bastions of life survive close to the heat of underwater geothermal vents. But in time, the last drop of liquid water hardens into stone. Life in the sea is extinguished.
On the surface, the wind becomes visible for the first time—but no one is left alive to see it. Air condenses to droplets; the atmosphere briefly ripples and flows. Streams of liquid air cascade over dead continents, rippling down ice-plugged river basins. Soon these new streams, too, freeze solid. The airless vacuum of space settles now like a cold blanket on the land. The wind is gone forever.
MUCH LIKE WIND on Earth, the ocean of plasma deep in the sun is fluid-like—it rises, stirs, and flows. Heat from deep in the sun’s core surges upward like a geyser through the radiative and convective zones to breach the photosphere, the cooler surface layer we see—but dare not look at directly—from Earth.
Sir Isaac Newton stared for hours at the sun’s image in a mirror in 1663, hoping to decipher and understand the nature of light. He tried to drink in the sun’s secrets with his eyes. A knife of light and heat carved the sun’s image on his retinas. He did not go blind, but salty tears of pain streamed across his pale skin. “To recover the use of my eyes [I] shut myself up in my chamber made dark three days together and used all means to divert my imagination from the Sun,” he wrote in warning.
The photosphere—the outer rim of the sun—burns at a maximum of only 11,000 degrees Fahrenheit, cooler even than lightning in the stormy skies of Earth—almost mild in comparison to the inferno at the sun’s core.
The sun is a yellow orb that never blinks save twice a day, at dawn and dusk. We see only the outermost edge of the daystar. Sometimes the sun’s face is blemished by dark pools of sunspots, relatively cold but at 6,700 degrees still furious enough to melt skyscrapers into puddles of steel. The wispy gasses of the corona, visible only during a solar eclipse, burn even brighter, at three million degrees.
Here at the photosphere is where the forces that produce wind and weather launch themselves into space toward the tiny blue and green satellite called Earth, a bright speck nearly lost among the stars.
THE SOLAR WIND is not a wind in the ordinary sense. It explodes as a stream of protons and other charged particles to flood the cosmos. The solar wind radiates in all directions; only a tiny fraction spills out of the sun at an appropriate angle to reach and intercept the Earth.
The solar wind races at speeds of up to 600 miles per second, accelerating as it spews outward into space. A solar flare—a storm of unusual intensity erupting from the sun’s depths—increases the power of the solar wind. This sudden outpouring of energy hits Earth like a wave crumbling against the shore.
Solar wind penetrates our upper atmosphere and sprinkles the sky with ions. These charged particles—molecules of nitrogen and oxygen with an unbalanced ratio of protons and electrons—slice through our planet’s pale gaseous skin and make the unseen air become visible. They release visible wavelengths of light upon shedding the extra energy and returning to their natural state. We see air molecules hit by bursts of solar energy as the northern lights—aurora borealis—candelabra lit high in the ionosphere, 60 to 80 miles above the surface, where the air is far too thin to breathe.
Alien and full of mystery, the northern lights ignite miles above the highest cloud. These shimmering lights puzzled the ancient Vikings, who believed the aurora originated in mysterious cities at the Pole, earthbound Valhallas inhabited by the gods. Who could have guessed that what they saw in the icy night sky above the arctic circle was actually the earthly residue of monstrous storms on the sun?
Sheets of dancing flame fill each aurora. Viewed from a mountaintop, the aurora shimmers and gleams, a thin veil of incandescence wrapped around the occasional shooting star.
THE SUN’S RAYS hit Earth squarely only at the equator and in the tropics. There, the sun perches in the zenith at noon and easily penetrates the atmosphere with abundant heat. At the poles, the angle of incidence is much greater (due to the curvature of Earth and the 23.5-degree tilt to the planet’s axis) and the sun’s rays hit the ground at a slant. The sun appears much lower in the sky; as a result, sunlight makes a longer passage through the atmosphere and its energy is diluted. The oblique angle at which it strikes Earth’s surface also spreads its energy over a greater surface area, bringing the region little warmth. Hold a flashlight perpendicular to a wall, and its light will be bright and focused over a small circle. That represents sunlight at the equator. Now tilt the flashlight (or the wall). Suddenly, the same amount of light—the same energy—must cover a larger area. It weakens in intensity, just like the slanted sunlight at the poles.
Air climbs away from the warmth of the tropics, launching itself into the sky with a burst of energy, then sinking again near the poles. Cold and warm air masses rub together above the surface, pushing and shoving for territory like armies at war. The ebullition of their contact is what we call wind.
Although the planet’s rotation siphons the wind off in odd directions and makes it swirl, in a process we call the Coriolis effect, it is the uneven heating of Earth’s surface that sets the whole process in motion. The wind stirs under the yellow eye of its creator, the distant sun.
ONE MORNING I saw a layer of altocumulus press down on the rising sun like a thumb, squashing it into the shape of a square. Pinched between the clouds and the ground, the sun ruptured; red and yellow streams spilled into the sky. At last, singed by fire, the heavy lid of clouds blackened and lifted away, allowing the sun to roll off the horizon. And so the cycle was renewed, and the endless chase of dusk and dawn revived for yet another day.
AS DAY YIELDS TO NIGHT, BOTH THE WEATHER AND THE MOOD of the sky must change. An entire hemisphere points to the stars, effectively switching off the sun.
Night is the time of screech owls and shadows, of grunts and stealthy footsteps by unseen creatures. Human beings have always feared the night—we lock our doors, shut our eyes, and hide. But why?
We cannot escape. The planet spins eastward along the equator at 1,038 mph (1,670 kph), a rotation which whisks away the blue hue of daylight and the lingering vermilion sunset, replacing both with an utter absence of color. The entire circumference of 24,900 miles turns once. The air vanishes, gone, invisible. A solid black dome appears in its place, speckled by starlight, lit only by the subtle radiance of the Milky Way.
“Twinkle, Twinkle, Little Star” is a old French folk song readapted by Wolfgang Amadeus Mozart, who wrote new words in German and composed several piano variations before moving on to bigger and better orchestrations. But what causes stars to twinkle in the first place? Mozart probably didn’t know or care, and most of the children still singing his nursery rhyme don’t stop to wonder. But the question has some bearing on the science of meteorology. It illustrates a curious and important fact about the 400-mile-thick atmosphere twirling endlessly around our bodies, rising far overhead to the brink of space.
The starlight we see takes a long journey before it enters our sky. Waves of light spurt off the photospheres of distant suns and streak across the universe for uncounted millennia. Eventually, inevitably, a few of these tendrils of luminosity enter our solar system: photons from Betelgeuse, Rigel, Polaris, Vega, and the 2,500 other stars visible to the naked eye, plus billions more that require magnification to be seen. Silently, they all pass through the stacked layers of air that surround the Earth: the exosphere, thermosphere, mesosphere, stratosphere, and troposphere.
No one hears starlight arrive and, for most of the sleeping inhabitants on the dark side of Earth, no one sees it. But careful eyes can still detect the Earth’s atmosphere after dark. It shimmers. Above it, the stars seem to twinkle and gleam.
The arrival of starlight is announced by visible fluctuations as light waves travel through banded layers of air, each one separated from the others by sharp changes in temperature and density. At each boundary, light refracts at an angle, in much the same way sunlight will bend if it passes from air into water. Place a spoon in a glass of water, and it will appear disjointed at the liquid’s surface—an illusion. In the sky, many such boundaries exist. Far above us, the loops and meanderings of a thousand coils of wind crisscross the sky with increasing complexity. And somehow the glimmering starlight must cut through. These feeble beams, which have shone steadily for a trillion trillion miles, in the last ten miles of the journey suddenly wink and quiver in the night, bent and refracted by changes in the temperature—and therefore in the thickness, the density—of air. In space, stars do not twinkle. The fact that they tremble so suddenly in the night sky tells us that our atmosphere is intact. It tints the heavens with little color and no warmth.
I watch for a while as the flickering beacon of Polaris hangs dim and cold in the north. It winks sleepily. The temperature tonight is chilly for July. Cold Canadian air sinks through the troposphere, spreads south, and flows down the slopes of mountains along the east coast of the United States. It pools in sleepy valleys, including the tree-rimmed village in New Hampshire where I live. Sluggish breezes stir unseen, unfelt, in the hour before dawn.
“RED IN THE morning, sailors take warning” is an old adage that glides easily off the tongue, as well it should; generations ago, the ability to read the sky’s mood in colors and hues meant life or death. A fisherman at sea who ignored the warning signs of a looming storm often lost more than just his catch.
“Red at night, shepherd’s delight” is another old saw. But why is a red sky at night sometimes a boon, a hallmark of good weather, while the same crimson clouds at dawn bring danger?
Even the Bible brings up the matter. In the King James version, in Matthew 16:2–3, no lesser authority than Jesus remarks, “When it is evening, ye say, It will be fair weather: for the sky is red. And in the morning, It will be foul weather to-day: for the sky is red and lowering . . .”
This morning at the eastern edge of the forest, the sun’s rays cut through the atmosphere at a slant. They illuminate wispy clouds called cirrus uncinus in the west. These ice-crystal clouds ripple and flow four to six miles above the surface like airborne tresses of gossamer hair, stroked and combed by the jet stream. Beneath them, but still far above the ground, altocumulus clouds advance from the western horizon. Air molecules and microscopic water droplets scatter the low, incoming sunbeams enough to accentuate one extreme of the spectrum, painting the clouds red. Combine that observation with the fact that weather systems in mid-latitudes usually travel west to east, nudged along by the planet’s rotation and the direction of the jet stream, and the mystery is solved. The angled rays of the easterly sunrise strike and color the advancing edge of a storm system approaching from the west; it has yet to arrive.
At sunset, the opposite holds true. If the sun sets in the west and illuminates high clouds in the east—or else it pinkens a dry, dusty air mass in the west carrying no threat of rain—chances are that the storm has already passed us by. The moisture-laden clouds continue to push to the east, out to sea, and a less-humid air mass takes their place.
Sailors and shepherds aren’t the only people concerned with colorful hues at dawn and dusk. “Evening red and morning gray, two sure signs of one fine day,” reads a popular rhyme from Europe. “A red sun has water in its eye,” I remember hearing as a child. “Evening gray and morning red sends the traveler wet to bed. Evening red and morning gray sends the traveler on his way.” Even William Shakespeare monitored changes in the weather. In Venus and Adonis, he writes:
A red morn, that ever yet betokened
Wreck to the seaman, tempest to the field,
Sorrow to shepherds, woe to the birds,
Gust and foul flaws to herdmen and to herds.
This morning, my earnest intention to climb a mountain may be stymied by the very color of the sky. In Shakespearean terms, the red dawn I see bodes ill. A low-pressure system is approaching from the Great Lakes, so the clouds will gradually thicken and lower until at last they dump moisture in the form of rain on the umbrellas of the Northeast.
In preparation for this deluge, I stuff a bulky waterproof rain parka into an easily accessible pocket of my backpack. I would prefer to hike light, but better safe than sorry. I head out the door, walkingstick in hand. Today’s events will test the accuracy of old proverbs about red skies. Will I need my rain gear, or not? Folklore and the wisdom of past generations say yes.
As I leave, a friend provides yet another example of folk wisdom, arguing simply, “If you take it, you won’t need it. But if you don’t, you’ll wish you had it.”
So perhaps I’ll try an experiment: weather folklore versus Murphy’s Law. Which will prevail?
AT 5 A.M., when the cock crows and songbirds chirp and chatter, their melodies reverberate in waves. Twilight thaws the sky. Sunshine extinguishes the stars, one by one. Soon the first gush of blue soaks the air. The clouds blush.
My itinerary today is to leave Crawford Notch and hike across the backbone of the Presidential Range, taking pictures as I go—up Mount Eisenhower, Franklin, and Monroe, and at last to the Lakes of the Clouds, perched above tree line in the shadow of Mount Washington. The sharply angled rays of the sun at this early hour offer the best opportunities for photography. As I watch, the sun pours down with a steady supply of sharp white flame. But I don’t see pure white—white is really all possible colors mixed and jostled together—nor do I witness a splintered rainbow of hues. I see a simple yellow orb in a blue sky.
Air is the substance of wind; it inspires a daily cycle of color from black to red to blue. Throughout the day, the wave frequency of blue light causes it to bounce and ricochet off oxygen and nitrogen molecules more often than any other color. “Preferential scattering” is the technical term. Ping! Bounce! Backward and forward, right and left—and soon the whole sky is frenzied with blue. The only way to escape is to duck your head and shut your eyes. So dominant is the blue wavelength that for most of each day the supposedly whitish sun burns with a soft, steady yellow, deprived of its azure hues.
“Why is the sky blue?” children ask their parents, who often stumble and stutter over an answer they learned decades ago and promptly forgot. The process is called Rayleigh scattering. Blue light has a shorter wavelength than red light, which causes it to scatter more easily in the atmosphere. The simplest way to picture this phenomenon is to employ an analogy. The smaller a person is, the bigger small objects appear. Just imagine a tiny ladybug crawling across a wool carpet. (I could see one on my living room floor as I packed my gear this morning.) To a tall human being, the rug looks flat and smooth; it is easy to walk across. But the ladybug discovers that the rug is a landscape rippling with hills and valleys—each carpet fiber is a mountain to traverse. The ladybug is small enough to detect every thread.
In the atmosphere, blue light flows with a wavelength of 0.4 micrometers, among the shortest in the visible spectrum. It is therefore short enough to “bounce” off the tiny oxygen and nitrogen molecules. Because the wavelength of red light is “larger” at 0.75 micrometers, it cuts through the clear air unimpeded—like a human striding across a rug.
A more interesting question is: Why is the night sky black? I was tossing and turning all last evening, somehow unable to sleep because I knew I must wake up early to prepare for this hike across the Presidential Range. To pass the time, I looked up at the stars and wondered.
An astronomer named Heinrich Olbers first asked the question, now known as Olbers’ paradox, in 1826. To him, a dark night sky seemed impossible. If the universe is all there is, forever unchanging, and the stars continue to pump heat into the cosmos for all eternity, then there should be no way to “lose” excess heat. The universe does not come equipped with a heat sink. Therefore, the nighttime sky should be blazing with light, as more and more heat pours out of the stars with nowhere to go.
But the sky is dark at night. Why? Olbers speculated that interstellar space is full of dust which absorbs the energy of distant stars. That provided only part of the solution. The true answer did not arrive until the middle of the twentieth century, with the Big Bang theory and our awareness of an expanding universe.
The universe “cools” itself by occupying a larger and larger volume. Meteorologically speaking, the explanation to Olbers’ Paradox is related to the question “Why does air get colder the higher up it goes?” In Earth’s troposphere, air cools adiabatically by expanding as it rises. Simply put, as a parcel of air reaches higher elevations, the number of molecules surrounding it decreases; as a result, so does the pressure. Elbow room appears, and the molecules spread apart. But expansion is motion, and motion requires work. Work is energy, and energy is heat. By expanding, the parcel of air cools naturally—and internally, with no loss or gain of heat to the surrounding air. It is a simple dictum of physics, vital to understanding weather on Earth. The dry adiabatic lapse rate of air causes it to cool 5.4 degrees Fahrenheit for every 1,000-foot increase in elevation. “Moist,” saturated air cools at a rate of 3.5 degrees per 1,000 feet. And on a much grander scale, a similar principle affects the heat output of stars in an expanding universe. A static universe—one which never changes size—should eventually blaze with light and heat in all directions, day or night. I prefer the universe we have.*
So far this morning, the blue tint of daybreak is pale and weak; it has not yet fully spread across the sky. The hour is still too early. In the east, deeper shades of red, orange, and yellow converge around the upper crescent of the newly risen sun. Cloud droplets, too small to see easily with the naked eye but still larger than air molecules, help scatter red wavelengths. Overhead, the sky’s rim now presses down on the sun and pinches it between two hills. The orb bulges, like a fruit squeezed for its pulp. As the sky clamps down, the colors of dawn spray in all directions.
CUMULUS CLOUDS STAMPEDE across the skyline a few hours after sunrise, but so far my rain gear stays safely stowed in my backpack. Red and orange hues long ago faded from the sky. The air is now a smooth, watery blue.
I pass a hand through a parcel of air in front of me and try to imagine the ping-pong cacophony of blue wavelengths swirling through my fingers. The action creates a cool breeze, evaporating a layer of sweat clinging tightly to my skin.
I have climbed halfway up a mountain in a corner of New Hampshire, hoping for a better view of the sunset, which is scheduled to arrive punctually at half past eight. My camera and tripod are dutifully at the ready. But the sun still has a long length of sky to tumble and roll through before it lands again on the horizon.
The trail winds up to the summit, a light-brown strip of color distinct from the surrounding gray rock, eroded by the footsteps of thousands of hikers who have trodden the path before me. I scan the white banners of clouds for signs of the advancing storm system. Cirrus uncinus clouds quickly yield to an icy gauze of cirrostratus far overhead. Wind whispers out of the southeast, never a good sign. In fact, a halo of light now circles the sun, refracted by six-sided ice crystals in the clouds. The optical phenomenon is a harbinger of a warm front, signifying a warm air mass slowly overtaking and sliding over the top of cold air. It is sure to bring precipitation. “The circle of the sun wets the shepherd,” I recall.
High on the mountain, hovering at eye level, a harmless cluster of cotton-ball cumulus belies the threat of higher clouds and the insinuations of the southeasterly breeze. According to the National Weather Service forecast, a storm will hit the mountain not long after the sun falls asleep at half past eight. Hopefully, that will allow me and dozens of other hikers plenty of time to get to shelter—if reports over the weather radio, interrupted by loud bursts of static, stay true. But nightfall will turn fierce and rainy with all the heat and fury of July. Much to the disappointment of shepherds, a red sky at dusk is unlikely to occur.
As the hours pass, low-level cumulus clouds cast shadows in the valleys and darken the lower hills. We hikers have climbed among them. Just as young children stand on tiptoe to touch a leaf on a high branch, so we now stretch our limbs and try to brush against the woolly bellies of clouds.
Standing at an altitude where the cumulus clouds frisk and play, I shield my eyes from the sun and peer into the east. Clear air stretches for 95 miles. But below me, a milky gray undercast—stratocumulus—fills the entire valley. Rippling clouds separate distant peaks like islands, drowning the lowest hills in fog.
“Doesn’t it look like we could just walk across the clouds from mountain to mountain?” sighs a tall hiker with a red bandanna wrapped around her forehead. As she passes by, she points with the tip of her walkingstick to the nearest peak, thrust like a volcanic island above a choppy sea of cloud.
Table of Contents
|PART I: AN OCEAN OF AIR||3|
|1. Born in the Belly of the Sun||5|
|3. A Ladder to the Sky||35|
|4. Fire in the Sky||42|
|5. Music of the Spheres||53|
|6. Fresh Air||61|
|7. Calling the Clouds Names||70|
|PART II: SEASONS||83|
|8. Tiptoeing Through Autumn||85|
|10. Snow and Ice||100|
|11. Cold Spring||114|
|12. The Invasion of Summer||128|
|13. Spirit of the Winds||139|
|PART III: EXTREME MEASURES||153|
|14. Tying Down the Wind||155|
|15. The Big Wind||166|
|16. Dancing the Tango with Mother Nature||177|
|17. Adventures in Weather||185|
|18. Going to Extremes||195|
|19. Chasing the Sun from Pole to Pole||206|
What People are Saying About This
Eric Pinder’s enthusiasm for weather watching is contagious. He takes you to the mountaintop and shows you the secrets of the sky.
(Jan DeBlieu, author of Wind: How the Flow of Air Has Shaped Life, Myth, and the Land)
Tying Down the Wind is a book I have been hoping to discover for a long time. In the admirable tradition of Chet Raymo, Eric Pinder mixes strong science with a highly readable, witty, and often lyrical style. By mixing in his own experiences as a weather observer atop Mount Washington, one of the world’s truly remarkable mountains, he makes even the most complex meteorology come vividly alive. I highly recommend this book to anyone interested in nature’s great mysteries.
(McKay Jenkins, author of The White Death: Tragedy and Heroism in an Avalanche Zone)
Eric Pinder pulls off the astonishing feat of turning the science of meteorology into the stuff of grand drama and stirring poetry. After reading this book, I found myself squinting up at the sky with new appreciation-and deeper understanding. A wonderful marriage of art and science, this book is entertaining and impressive in every way.
(David Laskin, author of Braving the Elements)
MARK TWAIN ALWAYS HAD PLENTY TO SAY ABOUT THE weather, particularly New England weather. "Cold!" he once wrote. "If the thermometer had been an inch longer we'd all have frozen to death."
Perhaps his most famous quotation is a phrase he borrowed from Charles Dudley Warner, a Hartford, Connecticut, newspaper editor, in 1897: "Everybody talks about the weather, but nobody does anything about it."
Twain wasn't the only one who thought that way. An old joke still making the rounds in the North Country (which humorist Bill Bryson recalls in A Walk in the Woods) is about how winter seems nine months long, followed by "three months of not-so-good sledding."
I've lived in the Northeast all my life, through heat waves and blizzards, thunderstorms and freezing rain, so I'm no stranger to the vagaries of weather. But even as a child I always wanted to know more. In answer to Mr. Sam Clemens' complaint, I didn't want just to talk about the weather--I wanted to do something about it.
"What is wind?" is a question I first asked myself--with the intent of writing about it--while walking through a woody corner of Massachusetts on a frosty autumn evening at the age of 24, listening to invisible breezes sift and surge through the pine branches. This book is the end result of my attempt to find the answer.
IN THE SPRING of 1995, I left Massachusetts and seized an opportunity to investigate the wind like never before. Where better to study the science of meteorology than on a rime-crusted mountaintop at an observatory devoted specifically to that purpose? So I journeyed to a summit where the wind never stops howling and snow falls in July.
My intention was to stay for only a season (the "not-so-good sledding" one, which most people call summer). Little did I know that for years to come I would live there and once almost die there.
Something in the wind gripped my imagination and refused to let go.