18 Miles

by Christopher Dewdney

  As usual, the Romans put their own stamp on the Anemoi, although mostly it was only a shift of nomenclature. The god of the north wind, Boreas, became Aquilo, while the south wind, Notus, became Auster, from which Australia and the aurora australis are derived. For the Romans, Auster took on the additional responsibility for the sirocco, with its heavy cloud cover and humidity. Zephyros, god of the west wind, became Favonius, and the divisional winds were known collectively as the Venti, to which the Romans added Tempestates, the goddess of storm winds.

  All of the Anemoi found themselves portrayed on one of the most singular monuments to meteorology ever constructed in the late classical period of Greece. It was a fusion of mythology, chronology and the budding science of forecasting.

  The Architecture of Wind

  The Tower of the Winds, an eight-sided marble clock tower built by Andronicus of Cyrrhus in the second or first century BCE, still stands in the Roman Agora in Athens. It is 39 feet tall and 26 feet in diameter with a sundial on each face. When it was operating, it contained a water clock and was surmounted by a wind vane, a bronze figure of Triton whose trident pointed in the direction of the prevailing wind. (Wind vanes became very popular among well-heeled Romans. Within a century, the grandest villas in Rome boasted their own personal wind vanes, some of which connected to a pointer contained in a compass on the ceiling of the room beneath. The first meteorological instruments.)

  The Tower of the Winds is aligned to the true points of the compass, with four sides of the octagon facing the cardinal directions and the other four sides bisecting them. Atop each of these facets is a sculpted depiction of the wind god that presides over that direction. They are winged, flying from left to right. We see Notus with his inverted water jug and Boreas blowing through a large shell. Lips holds the stern of a ship while a seminude Zephyros carries a host of flowers.

  Vitruvius probably wrote The Ten Books on Architecture during the reign of Augustus, a hundred years or so after the construction of the Tower of the Winds. The exact date is disputed. Some say he wrote it during the reign of Nero. What is known is that he was an ambitious, talented architect, who courted the favor of Rome’s patrician classes, particularly the Caesar, to whom The Ten Books on Architecture is dedicated.

  In a chapter called “The Directions of the Streets; with Remarks on the Winds,” he draws upon the writings of the Greek philosopher Hippocrates, who, five centuries earlier, wrote that towns or cities “that lie toward the risings of the sun are likely to be healthier than those facing the north and those exposed to the hot winds” and that their “inhabitants are of better complexion and more blooming than elsewhere . . . They are clear-voiced, and with better temper and intelligence than those who are exposed to the north.”

  In a similar vein, Vitruvius maintained that “cold winds are disagreeable, hot winds enervating, moist winds unhealthy.” This is entirely in keeping with Italy’s long and fraught relationship to draughts, winds and humidity, which has come down to us today virtually unaltered. I’ve taken train rides in Italy on unbearably hot days where not a single window in my coach could be opened for fear of someone getting sick from the draught. Vitruvius goes on to use the ill-aligned town of Mytilene, on the island of Lesbos in Greece, as an example of bad planning. It looks like a lovely place, but the positioning is all wrong: “In that community when the wind is south, the people fall ill; when it is northwest, it sets them coughing; with a north wind, they do indeed recover but cannot stand about in the alleys and streets, owing to the severe cold.

  Villa of the Winds

  The caves of Costozza in the Berici Hills of Vicenza have been celebrated by poets as sources of inspiration and divine insight since Roman times, but it was only during the Renaissance that Costozza’s caves realized their climate-control potential. An opportunistic architect connected them to the adjacent Roman quarries and created an ingenious underground network of tunnels and caves. These formed a system of ventilation ducts that supplied three villas — Villa Eolia, Villa Trento-Carli and Villa Trento-Buoni Fanciulli — with the Renaissance version of central air.

  The architect in question was Francesco Trento, who built the first of his three villas, Eolia, in 1560. It still stands in Costozza, an unremarkable, squarish edifice that is rescued by its more opulent interior — a large hall surmounted with a domed, frescoed ceiling. On the floor in the center of the room (now a restaurant) is an ironwork grate through which the wind rises from the subterranean networks. The grate forms the oculus, or window, on the ceiling of an eight-sided chamber beneath the hall (currently the restaurant’s wine cellar), which contains eight empty niches in each of the walls. Just beneath these niches are inscribed the names of the local winds: Borea, Euro, Sirocho, Austro, Garbin, Zefiro, Maestro and Tramot.

  In these names, we can decipher a mixture of Greek, Roman and local names. Borea might be a variation of bora, the cold, northeaster blowing out of the Alps; in Euro, we can recognize the Greek god of the east wind. Sirocho, of course, refers to the sirocco, the infamous southeasterly wind. Austro is probably a variant of Auster, Roman god of the south wind. Garbin is more mysterious, because the garbin is a Spanish southwesterly wind that blows from the Atlantic whilst the libeccio is an Italian southwesterly wind coming from the Mediterranean. Perhaps the Spanish term was an artifact from the period of Spanish rule. Zefiro, reminiscent of Zephyros, is probably the west wind of the western Adriatic, and Maestro is a strong summer northwesterly wind that blows in the same region. Tramot is probably a derivation of tramontana, the cold Alpine north wind.

  Trento elaborated the natural air-conditioning theme with his next construction, the Villa Trento-Buoni Fanciulli, which not only had an underground wind channel but also a network of vertical conduits embedded within the walls that conducted cool, moist air to various rooms. These remarkable innovations were the architectural wonders of the time. “As I have experienced, nothing but a Terrestrial Paradise is sensed in these freshly ventilated rooms,” wrote Francesco Barbarano, a priest and historian who chronicled the wonders of Trento’s villas. They did more than refresh, however: they also embodied the Renaissance’s architectural fascination with pneumatology, the science of enhancing the vitality of air and, along with it, the human spirit. Trento’s Eolia and Fanciulli were ville spiritali.

  The classical principles of proportion and elegance combined with the science of air (pneuma) and wind (spirit) saw their Renaissance apogee in the Villa Rotunda, completed by the architectual genius Andrea Palladio in 1566. Situated atop a hill, with four grand loggia and pediments facing the cardinal directions, the Villa Rotunda recalls Andronicus’s Tower of the Winds. The Villa Rotunda had a cooling chamber à la Trento beneath the central rotunda that vented upward through a grate. The cool air then rose through the room, exiting via an oculus at the peak of the rotunda. This passive central air system provided constantly flowing cool air in the summer for the lucky owners of Palladio’s architectural masterpiece.

  Famous Winds:

  from the Föhn to the Sirocco

  “It has now blown for these six days without intermission; and has indeed blown away all our gaiety and spirits; and if it continues much longer, I do not know what may be the consequence.”

  Patrick Brydone,

  Scottish traveler, 1776

  One of the directional winds inscribed on the eight-sided apse beneath the floor of Villa Eolia is notorious. It is the Siroch, known today as the sirocco. If Trento had built his pneumatic edifice a little further north, in the Alps, then another local wind might have usurped the infamous sirocco, namely the föhn, a regional wind with a fearsome reputation and a complex genesis.

  When large, humid air masses are pushed up the windward sides of tall ranges, such as the Alps or the Rockies, the mountains wring out every drop of moisture. This is because air expands as it rises in the lower pressure of altitude. In the thinner air, the molecules spread out and vibrate more slowly. But th
e molecules need energy to expand, and so the air cools in spite of the fact that no heat has been removed from it. It’s a sleight of hand of physics called adiabatic cooling. When the air is moist, the cooling process is slowed down. When it’s drier, adiabatic cooling speeds up.

  The side effect of adiabatic cooling is rain and snow. Any moisture in an air mass that is pushed up the side of a mountain condenses, forming clouds that then release precipitation. A moist air mass will wreath a mountain summit in rainy gloom, called orographic rainfall. Under special conditions, after being thrust over the top of the mountains, the dry air rushes down the leeward side. It recompresses as it sinks and gains heat in a reverse adiabatic reaction that is amplified by the dryness and rapid descent of the wind, sometimes warming by 10°C for every 3,281 feet in altitude. By the time this fast moving air hits the lower slopes of a mountain, it can be up to 40°C warmer than the ambient temperature of the valley.

  In the Alps, this hot mountain wind is called the föhn, the “witch’s wind.” The föhn spawns wildfires and conflagrations in summer and melts snow in winter. It always seems to be accompanied by human complaints — migraines, insomnia and worse. Some hospitals in Switzerland and Bavaria postpone major surgery during a föhn because rates of postoperative deaths from heavy bleeding and thrombosis increase statistically at those times. Literally an ill wind.

  In the Rocky Mountains, a similar kind of descending mountain wind, called a chinook, is famous for radical winter temperature swings. A chinook can be so dry and warm that it evaporates the snow in a process called sublimation (passing directly from a frozen to a gaseous state without melting first). In Lethbridge, Alberta, it is not unheard of for snow to evaporate at the rate of 12 inches per hour during a chinook. And the speed of the transition can be even more extraordinary. One day in January 1943, a chinook in the aptly named town of Rapid City, South Dakota, raised the temperature from -20°C to 7°C in less than five minutes. On January 15, 1972, a chinook took Loma, Montana, from -48°C to 9°C, a change of 57°C in less than 24 hours.

  It seems meteorologists are inordinately fond of confusing monikers, particularly when it comes to related phenomena. Not only can you have adiabatic cooling and heating on mountains according to elevation, you also get anabatic and katabatic winds. An anabatic wind is warm wind that’s blowing up the slope of a mountain and is caused by solar heating of the slope. A katabatic wind is one that blows air from a high elevation down a slope. The infamous Santa Ana winds of southern California are katabatic winds descending from the great arid plains northeast of the Sierra Nevada Mountains. The winds are so dry that, as they slide down the valleys of the Sierra Nevadas, they pick up heat as quickly as a föhn, making them blast furnace-hot by the time they hit Los Angeles and San Diego.

  Santa Ana winds fan the flames of southern California’s biggest wildfires. And like the föhn of the Alps, they also influence people’s temperaments. In his short story, “Red Wind,” Raymond Chandler wrote that on a night when the Santa Ana blows, “every booze party ends in a fight. Meek little wives feel the edge of the carving knife and study their husbands’ necks. Anything can happen. You can even get a full glass of beer at a cocktail lounge.”

  Other mountain winds are not so warm. The cold, dry mistral that howls down the Rhone River valley, reaching speeds of 93 miles per hour, ruins holidays in the French Riviera and the Gulf of Lyon. It has been doing so for thousands of years. Around 10 CE, the Greek geographer Strabo called it “an impetuous and terrible wind which displaces rocks, hurls men from their chariots, breaks their limbs and strips them of their clothes and weapons.” In contemporary times, it has been known to knock down brick chimneys, blow roofing tiles off homes and even topple railway freight cars.

  Not all ill winds are caused by mountains. There is another wind, a native of southern Europe and the Middle East, which is conjured mostly in the spring by low-pressure systems moving eastward across the Mediterranean. These lows snare hot, dusty, air funneled up from the Sahara desert and the Arabian Peninsula, supercharge it with humidity and then blow it inland.

  In Morocco, it is called leveche; in Tunisia, it is known as the ghibli; in Egypt, as the khamsin; in Iraq, it is called the shamal; in Israel, sharav; and in southern Europe, it is referred to by its Arabic name, sirocco. No one gives it good reviews. The Georgian-era travel writer Patrick Brydone devoted more than a page of his popular 1776 book A Tour through Sicily and Malta, in a Series of Letters to William Beckford Esq., of Somerly in Suffolk to the sirocco, talking about the lassitude, the headaches and the ennui it evokes in tourists. The local population is not immune either:

  A Neopolitan lover avoids his mistress with the utmost care in the time of the sirocc, and the indolence it inspires, is almost sufficient to extinguish every passion. All works of genius are laid aside, during its continuance; and when anything very flat or insipid is produced, the strongest phrase of disapprobation they can bestow, is that it was written in the time of the sirocc.

  A French acquaintance of Brydone’s complains, “‘Ah, mon ami,’ said he, ‘I am near to death, I, who never knew the meaning of the word ennui. Mais cet exécrable vent, if it lasts even two days more, I will hang myself.’”

  Two years before these lamentations were published, in County Meath, Ireland, Mary Beaufort, wife of Daniel Augustus Beaufort, gave birth to a boy who was destined to become master of the wind.

  The Beaufort Scale

  At first glance, it would seem that wind speed over water doesn’t get the same respect as wind speed over land. Why is it measured in knots instead of miles or kilometers per hour? It’s almost as if lakes and oceans render the exact velocity of wind a little more nebulous or approximate. Is the normal scale of wind speed no longer applicable near large amounts of water? What is it about water that makes such measurements subject to this strange conversion, like a foreign currency? Well, it all hinges on reference points. In order to measure wind speed accurately you need a fixed, immovable point, and that is hard to find in the open sea.

  On water, everything is relative — your ship is moving in one direction, the waves are moving in another and the currents beneath your bow are moving in yet another. So, maritimers use the Beaufort scale, which, as it turns out, is an ingenious way of accurately measuring a vessel’s speed.

  Daniel Beaufort was a Protestant clergyman and a member of the Royal Irish Academy. He was a first-rate classicist, a scholar, a society man and a crack cartographer, publishing in 1792 the most accurate map of Ireland. Unfortunately, he was also improvident. His young family had to keep moving to avoid the bailiff. They relocated six times in Ireland and England during the first 16 years of his son Francis’s life.

  As a result, Francis’s education was compromised, with one notable and critical exception. In 1788, at the age of 14, he attended classes led by Dr. Henry Usher, professor of astronomy at Trinity College Dublin. The classes were held inside the recently constructed Dunsink Observatory. Here he learned the nature of the stars, the constellations and planets. Through the great Dunsink telescope, he saw the crescent of Venus, surveyed lunar mountains and viewed the moons of Jupiter. He learned how to use a sextant to calculate his exact position on the global grid of longitude and latitude.

  Usher was a spectacular influence on the young Beaufort, honing his powers of scientific observation. In a celestial journal that Francis kept at this time is a description of a lunar halo, a sure sign of impending rain.

  On the 12th December, 1788 at a little after 11 o’clock I saw a circle around the moon at a distance of about 8’ or 9’ the breadth of it was a semi (diameter) of the moon it consisted of three shades, the internal one that next the moon was a lightish purple, next that a light red, and next a greenish yellow.

  A year later, Francis’s father secured a berth for him aboard the Vansittart, a three-masted frigate bound for Batavia in the Dutch East Indies (present-day Jakarta). It was the inauguration of his naval ca
reer. Three weeks into the voyage, Francis was named the official midday latitude observer. Indeed, the 15-year-old was so proficient with a sextant that he revised the official cartographic position of the city of Batavia by three miles. He was correct.

  Disastrously, a few days after leaving Batavia for the return voyage, the Vansittart struck a shoal that had been improperly marked on the nautical charts and sank. Beaufort survived the wreck and made his way back to England to enlist in the Royal Navy just in time for war with France. He rose rapidly through the ranks of the British navy; by age 22, he was appointed first lieutenant of the Mediterranean-based warship HMS Phaeton. There, in the fall of 1796, the Phaeton attacked and captured a Spanish brig. Beaufort was one of the first to jump aboard the enemy vessel, where he was shot at point-blank range with a musket, riddled with shrapnel from an exploding grenade and set upon by a saber-wielding Spaniard who delivered two heavy blows to his head.

  Again he survived, but he was laid up for weeks with a musket ball in his left lung and more than a dozen other wounds. A few years later, in 1805, he was given his first command. His vessel, the HMS Woolwich, was assigned to conduct a hydrographic survey of the coast of South America. This was followed by many more hydrographic surveys, and it was during these expeditions that he developed his first versions of his wind force scale, as well as rough notes for his book on forecasting at sea eventually entitled Weather Notation.

  In 1812, his Royal Navy surveys found him in the eastern Mediterranean commanding the HMS Frederickstein on a mission that also included patrols against local pirates. In June, a landing party from his ship was fired upon by pashas, and Beaufort went ashore to rescue his crew. As they were returning to the ship, a sniper shot Beaufort and the ball shattered his hip. He convalesced onboard for months and eventually returned to England, but he never saw active sea duty again, although he remained in the navy. In 1829, he was appointed hydrographer to the Admiralty; and in 1846, he was promoted to rear admiral. By 1838, the British navy adopted his wind force scale, which is still used by all seagoing vessels.