In summer we live out of doors and have only impulses and feelings, which are all for action . . . we are sensible that behind the rustling leaves, and the stacks of grain, and the bare clusters of the grape, there is the field of a wholly new life, which no man has lived; that even this earth was made for more mysterious and nobler inhabitants than men and women.
Heat Lags and Dog Days
Water warms more slowly than land, but even land takes time to absorb solar heat. This means that although the longest day of the year is June 21, it isn’t until the last week of July that summer heat climaxes. (A week later marks the peak temperature of North America’s southern Great Lakes — 21°C). In western Europe, the heat lag is shorter, more like a month, so the hottest days are in July. In San Francisco, because of the cold Pacific gyre, the summer lag is almost two months. Their warmest weather peaks in mid-August to September.
Chronologically speaking, the exact middle of summer falls on August 6, halfway between the June solstice and the September equinox. In Italy, they celebrate the height of summer nine days later, on August 15, with Ferragosto, a holiday that has a 2,000-year pedigree. In North America, the spell of hot, still weather around this time is referred to as the “dog days” of summer, a phrase you’d think originated from the behavior of dogs during heat waves: they lie down and pant. Actually, the phrase comes from the ancient Greeks and refers to the 40 days of summer, from July 3 to August 11, when the dog star Sirius rises above the southern horizon. This is also often the period of least rainfall in the northern hemisphere due to stable high-pressure cells setting up over temperate zones.
During heat waves, especially under a jet stream pattern locked in place, a temperature inversion can form and make things even hotter. It’s a reversal of the usual adiabatic trend of the atmosphere to get cooler with altitude. Instead, a layer of warm air forms at an altitude of 2,000 to 3,000 feet and traps relatively cooler air beneath, sometimes for weeks on end. I say “relatively cooler,” because during a heat wave, the temperature of the first thousand feet of the atmosphere can get very hot indeed. One sweltering July in 1995, Chicago, Illinois, suffered through a weeklong heat wave caused by an inversion layer. On the 15th of that month, the city recorded a daytime high of 37°C. The ERs were flooded with patients suffering from heat stroke and dehydration. But as heat waves go, that was mild.
The world’s longest recorded heat wave struck down under, in western Australia. The citizens of Marble Bar watched their thermometers climb to 38°C every day for five months, starting in November 1923 and lasting until early April, 1924. (It must have been one scorcher of a Christmas.) The hottest day on record wasn’t in Australia though; it was in Kuwait, in a small town called Mitribah. There, on July 21, 2016, the daytime high reached a searing 54°C.
People have always complained, “It’s not the heat, it’s the humidity,” although no one had accurately measured that subjective experience until it was quantified by two Canadian meteorologists in 1979. J.M. Masterton and F.A. Richardson took the dew point as the index of humidity relative to the temperature and produced a scale that was more accurate than the American heat index system, which is based on relative humidity alone. Their humidex reading is a single temperature, in Celsius or Fahrenheit, which accurately reflects how our bodies sense the heat. For example, if the temperature is a sultry 30°C and the dew point is a relatively dry 15°C, then the humidex number is close to the actual temperature at 34°C. But if the dew point is raised to 25°C, then the humidex number is a whopping 42°C.
Often the only relief from daytime heat is the cooling that night brings. As Henry Wadsworth Longfellow observed in his notes, “Oh! how beautiful is the summer night, which is not night, but a sunless yet unclouded day, descending upon earth with dews and shadows and refreshing coolness.” In clear weather, even during the most extreme heat wave, the temperature starts to fall at sunset and continues to fall overnight until it reaches its lowest point just before dawn, usually a drop of 7°C. If there are clouds at night, then the cloud layer traps the heat and the temperature drops more slowly, or not at all. Which is why people like to spend their dog days at the lake or by an ocean.
Even in the absence of prevailing winds, a large body of water will set up its own cycle of winds during hot weather. If the land is hotter than the water, there will be an onshore breeze as the updraft over the land draws in cooler air from the lake or ocean. Conversely, if the body of water is warmer, then an offshore breeze will set up at night as cooler air from the land is drawn into the updraft from the water. That’s one reason why people vacation by lakes and oceans. And by mountains.
Dry air cools adiabatically with height, so there’s immediate relief from the heat the higher you go. Mountains also amplify any prevailing wind the same way that tall buildings funnel air around them to blow your umbrella inside out. As well, even the stillest summer night can be interrupted by another kind of breeze altogether, a surprisingly strong, cool wind that flows down mountainsides. These katabatic winds are the result of cool air collecting on the mountain heights. Because cold air is heavier than warm air, the air begins to flow down the slopes like water off a roof, gaining momentum, not to mention heating adiabatically, as it descends. On a big mountain, these flows can become gale force winds, cool on the inclines and warm in the valleys. I’d like to imagine that is where Lucy Maud Montgomery’s lovers met in her novel The Blue Castle: “It was rapture enough just to sit there beside him in silence, alone in the summer night in the white splendour of moonshine, with the wind blowing down on them out of the pine woods.”
Autumn
“’Tis the last rose of summer,
Left blooming alone;
All her lovely companions
Are faded and gone.”
Thomas Moore
There is something exhilarating about the first cool days of autumn in the northern temperate zone. It’s not just because it’s back to school with new shoes and colored pencils; it’s because we are mammals. Autumn is our native season. We came into our own in the cool forests and savannahs of the Pliocene-Quaternary glacial period. In fact, all the temperate mammals underwent a final spurt of evolution at about the same time — dogs, cats, squirrels, chipmunks, hedgehogs, porcupines, bears, deer. And now, as the nights get cooler, they grow new fur coats to get them ready for winter. Change is coming, and every one of us mammals feels it in our veins.
Autumn has a definite fin de siècle ambience, but it also holds urgency; the preparation for the deep freeze gives it a sense of purpose. The chill air quickens the pace, and for many this is their favorite season. In “The Autumnal,” the poet John Donne insists, “No spring, nor summer beauty hath such grace, / As I have seen in one autumnal face.” And Percy Bysshe Shelley was definitely a believer. In “Hymn to Intellectual Beauty,” he wrote, “There is a harmony / In autumn, and a lustre in its sky, / Which through the summer is not heard or seen, / As if it could not be, as if it had not been!”
With the warm, serotinal weather continuing in September, the deserted beaches become a poignantly vacant stage for summer’s last drama, its decline. Arthur Symons’s poem “At Dieppe” (written in 1895, when Dieppe was a holiday destination, not a Second World War landing beach) catches the deserted-resort mood perfectly: “The gray-green stretch of sandy grasses, / Indefinitely desolate; / A sea of lead, a sky of slate; / Already autumn in the air, alas!” The same mood pervades Matthew Arnold’s poem “Rugby Chapel,”
Coldly, sadly descends
The autumn evening. The field
Strewn with its dank yellow drifts
Of withered leaves, and the elms,
Fade into dimness apace,
Silent; hardly a shout
From a few boys late at their play!
There is a pensive, meditative distance in these poems. But the atmospheric machinery of autumn is anything but languorous. As the northern hemisphere’s polar cell enlarges its fr
igid kingdom at the expense of the temperate mid-latitude Ferrel cell, the jet stream begins its 800-mile slump southward. By mid-autumn, it is already 400 miles south of its summer position, and northwest breezes are bringing the first cold nights. The leaves begin to turn, and, as fall progresses, their color deepens until the polychromatic autumn foliage takes on an almost hallucinatory ambience. In his book Songs: Set Two — A Short Count, the American poet Ed Dorn refers to the fall colors he witnessed once when crossing the border from upstate New York into Canada: “We done the crossing of the border / In the lysergium of September.”
I also feel the mammalian tug, the thrill of autumn, though it is outweighed by tremendous nostalgia for my favorite season, summer. For the poetic soul, the autumn can instill a vast, pathetic fallacy of lost paradise and poignancy, a mourning of departed love. It is unclear, for instance, if Alfred, Lord Tennyson was writing about summer or a lost love — or both — when he wrote,
Tears, idle tears, I know not what they mean,
Tears from the depth of some divine despair
Rise in the heart, and gather to the eyes,
In looking on the happy autumn fields,
And thinking of the days that are no more.
The same ennui infuses Paul Verlaine’s poem “Chanson d’automne”: “The long sobs / Of the violins / Of autumn / Pierce my heart / With monotonous languor.”
There is an even subtler reading of autumn, one that invokes the slightly spooky, somnambulistic ambience of late October and early November, when the short days yield to the somber empire of twilight. Ray Bradbury evokes the mood precisely in his short story “The October Country”:
That country where it is always turning late in the year. That country where the hills are fog and the rivers are mist; where noons go quickly, dusks and twilights linger, and midnights stay. That country composed in the main of cellars, sub-cellars, coal-bins, closets, attics, and pantries faced away from the sun. That country whose people are autumn people, thinking only autumn thoughts. Whose people passing at night on the empty walks sound like rain.
I think that the height of poignancy is not reached in September, during long walks on deserted beaches or passing by an abandoned amusement park on a rainy afternoon, but later, during “Indian summer” — summer’s aftershock, that last blast of warm weather in late October. In Europe, it’s called St. Luke’s summer or St. Martin’s summer, heralding a period of fine, warm weather that falls between October 18 and November 11. It is summer’s last hurrah.
Although fall officially lasts from September 21 to December 21 in the northern hemisphere (March 21 to June 21 in the southern hemisphere), winter’s invasion can often start with an overnight dusting of snow in October or November. Winter ends the seasonal cycle of evolution. It is the great null space that resets the clock to zero, just as it did in prehistory 700 million years ago, when a glacial age nearly eradicated life on our planet.
When I was young, during the first snowfalls of late autumn, I imagined herds of wooly mammoths gathering in the frosty gloom at the foot of glaciers, blue-green cliffs of ice that towered a mile high. And as the great mountains of ice ground their way southward, they crushed everything beneath them into powder and slush.
10
A Cold Place
Winter and the Ice Ages
“It was so cold I almost got married.”
Shelley Winters
A few days after Christmas, on a whim, you accept an invitation from a friend to celebrate New Year’s Eve at his cottage. When you board the bus in the early afternoon, it’s sunny and cold. The forecast calls for a high of -10°C with a light southwest wind, though a polar front is predicted to move in that evening. An hour later, as the bus reaches the turnoff from the highway, the wind picks up, and it’s beginning to snow, probably lake-effect snow flurries. You realize that the polar high must be moving in faster than predicted. Within another hour, it’s snowing heavily, and your bus seems to be the only vehicle on the road. You walk to the front and ask the driver how much longer to your transfer. “Fifteen minutes,” he says, and then adds, “There’s a weather advisory. I hope you’ve got something warmer than that coat. Those shelters can get pretty cold this time of year.” You tell him you don’t expect you’ll be waiting very long — the connecting bus is scheduled to arrive less than half an hour after you get dropped off.
At the transfer, the snow is so heavy you can barely make out the shelter in its headlights. After the bus leaves, it is surprisingly quiet — the silence of heavy snow. The shelter, built to resemble a cheery log cabin with three walls and a roof, is empty of passengers. You sit down to wait. It’s really cold. You take out your phone but there’s no service. You’re beginning to regret not wearing a heavier coat. At least you have a scarf and gloves. After an hour, you begin to wonder if the bus is coming. No cars are passing by. Have the police closed the highway? Night is closing in. Another hour passes, and you decide to start walking to get somewhere warm, back down the road. Wasn’t there a gas station near the turnoff?
You take a sweater out of your pack and pull it on along with an extra pair of socks. Setting off down the road into the accumulating snow, which, you notice with some alarm, is already up to your ankles, you realize you’re not dressed at all properly for this deep freeze — your coat is too light and your gloves are thin leather. You should have brought a hat. At least you’re wearing winter boots. You calculate how long it will take to walk back to the turnoff from the highway. Three, maybe four hours. The wind on your face is so cold it burns. With the arrival of the polar front, the temperature has already fallen below -15°C. Adding in the wind chill, it feels more like -22°C.
You plod on into the blowing snow. Sometimes you’re not sure where the road is, and twice you slip and fall. Daylight fades to night. Your phone’s flashlight only illuminates a dense cone of falling snow. You can see better when you switch it off. You try checking the time, but you’re shaking too hard. You’re well into the first stages of hypothermia.
Extreme cold is much more lethal than extreme heat. The British medical journal The Lancet analyzed the cause of death data from 13 northern and temperate countries between the years 1985 and 2012 and found that 5.4 million were from hypothermia. A higher percentage of these deaths were men, because men are more susceptible to hypothermia than women. But the physiological process follows the same course for both sexes.
Without a hat, you’re losing 10 percent of your body heat through your head. The snow has been building up in your hair, turning into a dripping helmet of ice that trickles down your neck. After an hour and a half outside, improperly dressed as you are, your core body temperature has fallen to 35°C, which is why you are shivering uncontrollably and violently. Your muscles are now cooling and tightening, causing you to walk in a stiff-legged, lurching gait.
You recall a passage from a book on meditation you read years earlier, about a monk who was tested by his master in the middle of winter to see how well he could control his metabolism. On a bitterly cold night, the master chipped a hole in the ice of a frozen river, and the naked acolyte sat beside the hole in the lotus position. The master dipped a blanket in the water and draped it over the shoulders of the acolyte who, over the next hour or so, had to dry the sheet with body heat. The master dipped the sheet in the icy water once more and the whole process was repeated until the acolyte had dried the blanket three or four times.
The reminiscence makes you feel chillier still. Your hands, even though you’re holding them under your armpits, throb painfully. They have cooled to 18°C. The outside temperature continues to drop as the polar front establishes itself. It is -20°C; with the wind chill factored in, it’s -27°C. At -28°C, exposed skin will freeze within 10 minutes. The tip of your nose is already numb, but something more insidious is happening. Now, for every degree that your core temperature drops below 35°C, your cerebral metabolism rate drops 4 percent. Your though
t processes are becoming irrational, and you are starting to suffer brief periods of amnesia. You are very cold, very tired. You have no idea how far you’ve come when you realize what a fool you’ve been. Why not let the insulating properties of the snow work for you. You’re too tired to keep walking anyway, and it’s too far to walk back to the bus shelter. Besides, you can hardly keep standing.
At the side of the road, you scoop out a hollow in snow and lie down, fluffing some snow over your body. Your core temperature is 32.2°C. Despite your snowy duvet, it’s falling a full degree every 30 minutes. When you reach 31°C, the shivering stops. A few minutes later, you have an overpowering urge to urinate. Your kidneys are being swamped by the overflow of fluid that the cold is constricting out of your extremities. This is the second last thing you’ll remember. At 30°C, your heart rate becomes irregular and slows. You begin to hallucinate voices, city sounds, flashes of light. These are accompanied by a sensation of growing warmth. Fortunately, you lose consciousness and don’t experience the paradoxical sensation of burning fever that often overcomes those whose core temperature falls below 29°C, which is why frozen hypothermia victims are sometimes discovered with few or no clothes on. They’ve torn them off in an ironic, and fatal, frenzy.
You’re lucky. You regain consciousness in a hospital room. Two teenagers on snowmobiles discovered you by pure serendipity when the vapor plume from one of your very occasional exhalations was caught in their headlights. By that time you’d been completely buried in snow except for your small exhalation vent. Fortunately, the emergency doctor who treated you knew what to do. Cutting into your abdominal cavity, she inserted two catheters, one to inject warm saline solution and another to drain it after the warmth had irrigated your stomach and intestines. Gradually, very gradually, she increased the flow of warm fluid, knowing that if she raised your temperature too quickly, you’d go into cardiac arrest and die.
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