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THE WEATHER, DAWN AND A BUTTERFLY’S FLUTTER
“EVERYBODY TALKS about the weather…” is sometimes attributed to Mark Twain, though just as nobody does anything about it, nor has this quote ever been verified as Twain’s. No matter, because the London Review of Books, November 5, 2015, encouraged weather talk by way of “Bright Blue Dark Blue” by Rosemary Hill, a review of Weatherland: Writers & Artists Under English Skies, a new book by Alexandra Harris.
Weatherland: Writers & Artists Under English Skies, by Alexandra Harris, Thames and Hudson, 2015.
Harris notes that changing seasons of ancient man were matters of ritual, but day-to-day weather was something to be endured, nothing more. It wasn’t until the late Middle Ages that concepts like “spring” were used. The “Bright Blue Dark Blue” of Hill’s title refers to illuminations in manuscripts of the era, bright blue skies in daylight, dark blue at night.
Scenes from the life of David in the Winchester Bible, c 1160 – 1180. Image from The Morgan Library and Museum.
Today, Hill observes that incessant talk about the weather is a myth, flattering “the notion of the English character being mildly eccentric—in a fundamentally likeable way.” On the other hand, people all around the world enjoy talking about the weather.
Before continuing, though, it’s useful to make clear the difference between weather and another term much in the news, climate. Weather refers to the day-to-day atmospheric phenomena of temperature, humidity, precipitation and the like. Climate refers to an accumulation of these data over extended time: years, decades, centuries, millennia.
Weather forecasting is highly probabilistic. Climate science, like any science, isn’t ever a done deal either.
True to its title, the book Weatherland: Writers & Artists Under English Skies discusses the weather and its appearances in English art and literature: Geoffrey Chaucer’s “Averylle with his shoures soote” and Charles Dickens’ fog, to name two.
This got me thinking of that old saying, “It’s always coldest just before the dawn.” In fact, I’ve even heard weather forecasters refer to this as “radiant cooling.” Whatever is this?
An internet search reveals explanations, some of them bizarre. But the Solar Semi-diurnal Tide appears a cogent one. Overnight, the air cools because of a lack of sunlight. However, its temperature is also affected by the Earth’s surface retaining heat of the previous day and radiating it back into a layer of atmosphere. The result is a moderated decrease in air temperature overnight—until just before dawn.
“It’s coldest just before the dawn.”
With the Earth’s rotation, the warming at dawn proceeds from east to west. This atmospheric difference in temperature disrupts that layer of radiated warmth and drops the air temperature, albeit only momentarily until the sunlight’s warmth overwhelms the effect. It’s enough to see a drop of a few degrees just at sunrise.
Another of my favorite weather phenomena is the Butterfly Effect. Coined by American mathematician and meteorologist Edward Lorenz, the Buttterfly Effect postulates how the flutter of a butterfly’s wings in the Amazon could lead, weeks later, to a blizzard in Duluth.
Edward Lorenz, 1917 – 2008, American mathematician and meteorologist, Professor Emeritus at MIT from 1987 until his death.
A key discovery of Lorenz was the non-linear nature of most atmospheric phenomena. Loosely, changes needn’t be proportional. What’s more, he investigated the concept of such dynamical systems being stable or unstable.
A system is structurally stable if it’s unaffected by nudges; mathematically, this means that small perturbations have no effect on the general behavior of trajectories. As an example, if a system exhibits damped behavior (like a free pendulum), it’ll continue to be damped even with changes of startup conditions. It’s structurally unstable if arbitrarily small perturbations (for instance, the butterfly’s flutter) can lead to marked changes later on (that is, the blizzard).
Like life, the weather isn’t structurally stable. ds
© Dennis Simanaitis, SimanaitisSays.com, 2015ll
Simanaitis Says 
Erik Larson also mentioned the butterfly effect in his book “Isaac’s Storm”, about the 1900 Galveston hurricane/flood disaster. Another worthy weather book is “de-fin-ing the wind” by Scott Huler, who entertainingly describes the development of the Beaufort Scale.
I’d always heard that quote attributed to a columnist at the Hartford Courant. Google turned this up:
http://quoteinvestigator.com/2010/04/23/everybody-talks-about-the-weather/