Here in Vermont, when we think about significant rain events, Hurricane Irene comes to mind. Compared to Houston’s Harvey, Irene’s statistics are modest. Only about 11 inches of rain in a day or so. But here the water is concentrated in the streams between the ancient hills and mountains. That’s where the roads were built and most of the towns and villages were established. So water velocity becomes impressive and a lot of earth is moved down stream. If we had the kind of rain Houston is having, with the exception of those of us who live on hills, Vermont would have to start from scratch.
On average Houston and Vermont get about the same amount of rain a year, 45 to 47 inches. But when the water hits the ground in Houston, it behaves differently. There are no rocky streams or deep valleys for the water to follow. In Harris County, where Houston has been built, the land is flat. Houston’s 667 square miles were originally swampland laced with bayous. Houston now has 22 square miles of water and 86 of parks. The rest is paved roads (including 739.3 miles of freeways and expressways in the metropolitan area on which 71.7% of its residents drive to work alone in their cars), parking lots and air-conditioned buildings, laced with bayous and man-made water courses. So there is no easy way for the water to get out.
In 2001 parts of Houston received up to 40 inches of rain, causing what was then the worst flooding ever known in that city. In August 2005 2.5 million people, the largest evacuation in U.S. history, left Houston in anticipation of Hurricane Rita, though little damage occurred. Reports are that parts of Houston will receive a total of up to 50 Harvey inches. Perhaps because of the embarrassingly unnecessary evacuation in 2005, there was no mass evacuation this time.
For those interested in statistics about rain on Houston: Large raindrops are roughly 5 mm (a little less than ¼ inch) in diameter. They can get as large as 9 mm, but above 5 mm they tend to break up into smaller drops due to air resistance. The larger they are, the faster they fall. The terminal velocity of a large raindrop is about 9 meters per second (30 ft./second – 20 miles per hour.) Based on estimates of an average of 30 inches of rain falling on Houston over the period of Harvey’s visit there I have worked it out that approximately 1,982,190,000,000,000 (nearly 2 quadrillion) large raindrops will have fallen on Houston’s 667 square miles. This amounts to 3,473,000,000 gallons or 14.5 million tons of water.
As to the effect of climate change, increased temperatures result in increased evaporation and therefore more rain. Of course the effects vary. Most of the increase is between 30 and 50 degrees north latitude. (Houston is nearly at the 30 degree line.) Higher temperatures in dry areas simply make them dryer. In the United States annual precipitation has increased by about 6% since 1900. In the American south the increase has been 11%. Heavy downpours have increased overall, with parts of Texas experiencing an increase of 700% compared to the decade of the 1950s.
A few years ago Fieldstone Publishing created The National Audubon Society Field Guide to Weather. There are now more than 500,000 copies in print. That doesn’t make me an expert, but it gives Fieldstone a foothold in this increasingly wet subject. (You can purchase a copy here.)
We at Fieldstone Publishing extend our thoughts and support to the people and communities of coastal Texas and Louisiana at this time of unprecedented crisis.
Yours From The Field,
The hills and forests of Vermont hide thousands of forgotten apple orchards and countless wild apple trees spawned from saplings planted in the late 18th and early 19th centuries. Sheep and dairy farmers created a long-term resource that could with a little attention be transformed into a fine drink to stimulate the spirit and bring a bit of frolic to the long winters ahead.
This is a particularly good year for wildflowers and fruit. The open grassy spaces are, in August, dense with wildflowers that come to take advantage of the few years before the neglected fields return to forest -- goldenrod, milkweed, Queen Anne’s lace, wild aster, dogbane, thistles, burdock. Around the edges of these open spaces, the forest is on its way to retake our old orchard. Wild cherries, maples, poplars, and wild apples (most of which have bitter or no taste) have joined the aged and weary apples planted a century or more ago.
My task is to return all this to the elegance of a well-tended garden of Cortland and Macintosh. The first step is to wrestle the brush hog onto the three-point hitch at the back of my John Deere. It is a 15 minute two-man job that I accomplished by myself in a little over two hours. I then climbed atop the machine and strapped myself in. (The orchard is steep in places, and I imagine myself pinned beneath the tractor if I neglect the harness from which, if I miscalculate John Deere’s center of gravity, I will find myself hanging between the roll bar and the rest of the machine.)
The key to mastering and rebuilding the orchard, as often occurs to me as I beat up and down the orchard hills and into the brush above the whirling blades of the brush hog, is steel, which of course, is mostly iron. Without iron there would be no blades, no tractor, not even an axes with which to confront nature’s intention to return the orchard permanently to forest. By a stroke of cosmic good fortune, iron is created as the last stage of fusion in high mass stars, and is released into space, and ultimately some of it into rocky planets like ours, by explosions known as supernovas. I am therefore grateful to the accidents of natural law that combine to help me with our orchard.
Yours From The Field,
My first introduction to the marvels of a solar eclipse was when I was a kid, in 1950, with the release of a remake of the movie version of “King Solomon’s Mines,” about the search for an explorer who was lost in darkest Africa while seeking the fabled gold (in the book, diamond) mines of King Solomon. The story was based on a novel by H. Rider Haggard and had previously been depicted in a 1937 film staring Cedrick Harwicke and Paul Robeson. In the 1950 full color version, our hero, Stewart Granger, has been persuaded by Deboarah Kerr, to risk his life in search of her not particularly well-liked husband. Granger and Kerr fall in love, fight wild animals and cannibals, and restore a king to his throne. In the process, Granger, who has been captured by angry tribesmen, and is well informed about matters astronomical, claims to have been sent from the stars and predicts an eclipse soon to occur if they don’t release him. As all hell is about to break loose, the eclipse occurs, and everything ends well for the hero. (In the novel it is a lunar eclipse, but I have a clear memory of a technicolored solar eclipse.)
The Chinese were able to predict solar eclipses as early as 2500 BC. Two Chinese astronomers were executed for failing to predict a solar eclipse, thereby endangering the health and success of the Emperor. (Indeed, solar eclipses can apparently be dangerous to kings, as one occurred immediately prior to the death of King Henry I.) The Babylonians were able to predict eclipses by the 14th century BC. Perhaps this helped Babylon to carry on until its passing as world power about 70 years after the destruction of the city of Jerusalem and the Babylonian abduction of the Jewish leaders in the year 587.
On the other hand, a solar eclipse may be a message of calm. Not only did it calm Hollywood’s African natives, but Herodotus reports that in the year 585 BDC, armies of the Lydians and the Medes, then at war with one another, were so frightened by the midday darkening of the sun that they immediately made peace.
A little more than 1,000 years later, in the year 632, a solar eclipse marked the death of the Prophet Mohammed’s son Ibrahim. You can draw your own conclusions about the significance of that event. I note only that if Ibrahim has not died, the Sunnis and the Shiites would have nothing to quarrel about, and the Iranians and the Saudis would be friends.
On average it takes 375 years for a total solar eclipse to happen again at the same location. There will not be another one to touch the territory of the United States until April 2024. So let’s make the most of the one we have next week and see if anything unusual happens at the White House.
Yours From The Field,
I am fascinated by the fact that an extended series of extremely unlikely conditions allowed life as we know it to exist on earth. For starters, each of the known four forces at work in the universe -- gravity, the electromagnetic force (e.g. light, etc.), and the less familiar but essential weak and strong forces determining the behavior of subatomic particles -– have to be what pretty much exactly they are. If any of them were significantly different, there would be no stars, planets, air, water, trees, Broadway musicals, or essentially anything we might enjoy.
Leaping ahead, there are other improbable but essential accidents. For example, the earth was born without a moon, but one came along only a few tens of millions of years after the earth was formed. At that time there were many more planetary objects in the solar system and many collisions. One important collision kicked a piece of earth off into nearby space sending plenty of stuff into orbit around the earth, finally coalescing into the moon.
The moon is spiraling away from earth at the rate of 1.5 inches a year. Calculating backwards, which I have just done, it appears that three billion years ago, when life first came about on earth, the moon, receding at its current pace, was roughly 75,000 miles closer than it now is – 165,000 miles rather than the present average distance of 239,000 miles, and it would have been spinning around, appearing larger by half and played hell with the tides. (The moon’s orbit is eliptical and its distance from the earth varies by up to 25,000 miles.)
Fortunately, during our time here the moon is perfectly placed to preserve our existence by stabilizing the earth, giving us predictable seasons and the right tides for the success of life. By remarkable coincidence it is also the right size and distance away to block all but the outer edge of the sun when seen from the narrow path of a total eclipse, allowing us to learn much about the universe that we would otherwise not know. Think how little we would know if the sky were perpetually cloudy.
Yours From The Field,
Anticipating the solar eclipse on August 21, let’s consider the sun.
The sun is of moderate age, 4.6 billion years – coalescing as a star from dust and gas when the universe was about 2/3rds of its present age. It was originally far larger than it now is, but the inward gravitational pull of the dust and gas squeezed together to the point that the sun’s interior is 8 times the density of gold. It cooks along at an interior temperature of roughly 28,000,000 degrees Fahrenheit, and a pressure of 250 billion times earth’s atmospheric pressure, just right for nuclear fusion.
It is expected that for the next 5 billion years the sun will continue to generate energy by converting four protons (hydrogen nuclei) into a single helium nucleus, which, being slightly lighter than the four protons, releases the small difference as energy. That energy release is equivalent every second to the energy of 100 billion one-megaton nuclear bombs. After that we can expect things to change. In the end the sun will turn into a red giant, and we had better have someplace else to go, because it will grow so large that it will consume the inner planets, probably including the earth. But it may warm the moons of Jupiter quite nicely, giving us another opportunity to do things right.
For now the sun is about right for life here in Vermont. If you want to see it disappear for about 3 minutes this month, consider traveling to Salem, Oregon, where at 10:20 AM PDT it will start its overland course from NW to SE, reaching the Atlantic just north of Charleston in South Carolina at 2:48 PM EDT.
Yours From The Field,