Time

Every year, just like you, I have a “birth day,” which is a misnomer as I am not born on that day every year, although I was once. When people ask me why I don’t like to acknowledge my birthday I tell them that time is a continuum. It breezes from one tiny fraction of a second to the next without counting where (when?) it has been or where (when?) it is going. There are no fractions of seconds, of course. We made seconds up and then when those were too large, we fractionated them into as many decimal bits as we needed.

Every year, just like you, I have a “birth day,” a misnomer as I am not born on that day every year, although I was once. When people ask me why I don’t like to acknowledge my birthday I tell them that time is a continuum. It breezes from one tiny fraction of a second to the next without counting where (when?) it has been or where (when?) it is going. There are no fractions of seconds, of course. We made seconds up and when those were too large, we fractionated them into as many decimal bits as we needed. We made minutes up at some point, perhaps when hours seemed too long or work seemed too slow. We made hours up when the days passed like sap in the wintertime. Days, weeks, months and years were strongly suggested by planetary, lunar and solar phenomena. To our credit, we noticed these patterns and live our lives waiting for them to begin – or end – a hard day, a boring hour-long meeting, a cold winter, a hot-and-muggy summer, the wet season, the dry season, etc. For a nice review, have a look at this.

Typically, though, we don’t think of times much shorter than 0.17 seconds. That is approximately the time it takes to count each of the six beats (or in poetry, “feet”) in “one-Mississippi,” etc. The “one” gets sort of two beats and the “Mississippi” goes in four. If we are keyed into a speed sport, we may split things down to the tenth of a second – I’m not sure I can do this, but I’m relatively certain that people who judge these kinds of events may have a refined sense of one-tenth of a second. Then it’s down to the hundredths of a second and, although all sorts of stopwatches and “photo finish” timers work in that realm, I can’t imagine that the human mind can honestly do much more than watch as the hundredths accumulate into tenths.

There are many time intervals that are extremely difficult for humans to comprehend, though, very short and pretty long. At one end of the range, we have a unit developed in physics called Planck time, named after Max Planck, one of the brilliant theoretical physicists of the 20th Century. This unit is defined as the amount of time that it takes for light to travel one Planck length in a vacuum. A Planck length (not a piratical plank length) is very short indeed: 1.616199×10−35 meters (m), which is about 1×10−20 the diameter of a proton, which is very tiny and comes in somewhere between 0.84×10−15 to 0.87×10−15 m. It is conceived of as the shortest theoretically measurable length within an order of magnitude (or a factor of 10). How much time is a Planck time then? It is a mind-bendingly brief 5.39116×10−44 seconds. Let me show you a comparison between numbers. First, we have 1/10 second:
0.10 or 1/6 second 0.17 (the “Miss” in “Mississippi,” let’s say)

Now, let’s show a Planck time:
0.0000000000000000000000000000000000000000000538116 seconds

Brief!

To say that differently, but not necessarily more helpfully, there are about 2×10+43 of these Planck times in one second (simply the inverse of 5.39116×10−44 seconds), which is obviously a huge number (2 followed by 43 zeros). The links for Planck time and length will allow you to explore this matter more thoroughly, but both use the speed of light (c=3.00×108 m/s), the gravitational constant (G=6.674×10−11 N⋅m2/kg2) and Planck’s constant (actually, the reduced Planck’s constant, which divides Planck’s constant by 2π), which is 1.054571800(13)×10−34 J⋅s. All this to say something quite simple – Planck time (and length) is derived in a fairly straightforward way using some well-established physical constants, although with some very careful consideration by Dr. Planck. His considerations have held up well; Planck’s constant is part of any useful high school chemistry or physics curriculum.

The real takeaway here is that time and action are inextricably linked. For a Planck time to elapse, a Planck length must be traversed by a photon in a vacuum. A photon must start somewhere and, on its way to somewhere else, it must etch a Planck length in space. This linkage is pretty neat, however resolutely transfixed and “motionless” the avid reader may be in their chair. How can I say that? Are we ever still? No.

Consider the amount of time it takes to absorb one photon of the appropriate energy into the electronic shell of an atom. The photon is either moving at the speed of light (in a vacuum) or somewhere close to this speed if it is traveling through a non-vacuum medium. This modified speed of light is calculated by dividing the speed of light (c) by the index of refraction (n). The higher n is the slower the modified speed of light. Here’s a table of diminishing speeds of light:

Material Index of Refraction
Vacuum 1.0000 299,792,458 m/s
Air 1.0003 299,702,547 m/s
Ice 1.31 228,849,205 m/s
Water 1.333 224,900,569 m/s
Ethyl Alcohol 1.36 220,435,631 m/s
Plexiglas 1.51 198,538,052 m/s
Crown Glass 1.52 197,231,880 m/s
Light Flint Glass 1.58 189,742,062 m/s
Dense Flint Glass 1.66 180,597,866 m/s
Zircon 1.923 155,898,314 m/s
Diamond 2.417 124,034,943 m/s
Rutile 2.907 103,127,781 m/s
Gallium phosphide 3.50 85,714,285 m/s

If the energy of an atom and the energy of a photon, moving at whatever speed after going through whatever medium, are compatible, the photon is absorbed by the atom with an electron quantum leaping proportionately. This process takes about 1 femtosecond or 1x10−15 seconds (or 0.000000000000001 seconds). There is some infinitesimal distance involved in these transitions, but the distances, if they are meaningful at all, are on the order of Planck lengths and do not add meaningfully to the time it takes a photon to be absorbed.

Photon Absorbance transitions
Source

After that absorption occurs, a new cascade of intra-atomic events occur, each with an associated time, each a tiny bit longer, slower, more human-paced, than the absorption event. I would enumerate them, but instead, I’ll just use a picture, a table and a video for your edification.

Screen shot 2011-03-01 at 9.51.13 AM.png

Source

Table 1

Transition Time Scale Radiative Process?
Absorption 10-15 s yes
Internal Conversion 10-14 – 10-11 s no
Vibrational Relaxation 10-14 – 10-11 s no
Fluorescence 10-9 – 10-7 s yes
Intersystem Crossing 10-8 – 10-3 s no
Phosphorescence 10-4 – 10-1 s yes

Source

The other completely nuts thing to keep in mind is that every single molecule and ever single atom in your body is vibrating and rotating – continuously! Every molecule we breathe, eat, digest, incorporate into our teeming collection of collaborative molecules is doing exactly that same thing. Here is a set of nifty .gif images to help you imagine the critical turmoil going on inside (and around) us all:

Symmetrical stretching.gifAsymmetrical stretching.gifScissoring.gif

Modo rotacao.gifWagging.gifTwisting.gif

(Source: https://en.wikipedia.org/wiki/Molecular_vibration)

These represent the different modes of vibration along covalent bonds. In addition to this motion, there are the rotations of each atom at the ends of each bond – and these modes of rotation get complicated really quickly, with spin orientations and precessing (this is what a top does when it spins – the wobble is precession) around axes. It’s all really a maddening, continuous mechanism of complexity. Even if all these molecules inside us were cooled to absolute zero, the motion would continue, although slowed. And all of them are like tiny clocks running at tiny fractions of a second – at an astonishing rate of speed, at roughly 10,000,000,000,000 to 100,000,000,000,000 times per second.

But I am writing about time, not intra-atomic events, and we could all easily be lost inside an atom for the rest of time if caution is abandoned. It is part of the definition of being a chemist – getting lost in the atoms (or at least the molecules). And with phosphorescence events taking a tenth of a second (1×10-1 seconds (or 0.1 s)), we’re at the interval for phosphorescence and can almost comprehend this.

Let’s move on.

Human lives are measured in seconds as well. Nine months of gestation is 23,328,000 seconds (give or take); ask any mother and she will be able to vouch for the satisfaction and endlessness of each second. We go to first grade at 6 years or 189,216,000 seconds and graduate high school after 567,648,000 seconds. Lives get into a murky middle bit after this and people hit benchmarks at various times, but it all comes down to life expectancy in the end. The people in Monaco, one of the richest in the world, have an average life expectancy of 89.52 years, which is 2,823,102,720 seconds – almost 3 billion seconds, people, while the people of Chad, bordered by Nigeria, Niger, Libya, Sudan, the Central African Republic and Cameroon, have a life expectancy of 49.81 years – 1,570,808,160 seconds – very close to being half the average life expectancy of people in the Principality of Monaco, bordered on three sides by France and on the fourth by the Mediterranean, home of casinos, yachts and the Grand Prix. In the United States, average life expectancy is 79.68 years or 2,512,788,480 seconds, 311 million seconds less than the average citizen of Monaco; when stated that way, it seems like a huge difference, doesn’t it?

But we’re not done measuring out human life. In the U.S., we count forward from 0 (zero) B.C. and are currently in the year 2016 as I write this. Two thousand and sixteen years is composed of 63,576,576,000 seconds, only about 22.5 Monaco lifespans ago, but 40.5 Chad lifetimes ago (sort of crazy when you consider it that way). But B.C. (or B.C.E., the term used by anthropologists and anyone studying world history instead of Western European and Middle Eastern history) is just a convenient temporal interrupt in a much longer series of events.

Our species crept into the genome around 200,000 years ago – a time that dwarfs the 2,016 years B.C.E. by two orders of magnitude or roughly 100-fold (100 x). Two hundred thousand years is a whole bunch of seconds – 6,307,200,000,000 seconds, or six trillion three hundred seven billion, two hundred million seconds (the time seems more awesome when typed out as words). But we’re not done yet. Anthropologists have found lots of bones of our ancestors, our nearest relatives to the great apes appearing between 6 and 7 million years ago, 30 to 35-fold more time than for the slow evolution of Homo sapiens, or between 189.2 trillion and 220.8 trillion seconds ago (keep in mind that the 0.2 and 0.8 in those number represent 200 billion and 800 billion seconds).

But let’s keep going. The Cretaceous–Tertiary (K–T) extinction occurred around 65 million years ago; current theories favor a huge meteor striking the earth in the northern Yucatan peninsula; 2,049,840,000,000,000 seconds ago (2 quadrillion seconds). But the earth is believed to have coalesced from hot gases and particles of stardust into something like its current orbit around the sun around 4.5 billion years ago; various models move the digit after the “5” around (is it 4.49 or 4.54?), but there is general scientific consensus around the 4.5 billion figure. 4.5 billion years equals 141,912,000,000,000,000 seconds quadrillion seconds ago, and it was not a livable planet at the time.

The universe, on the other hand, is yet another order of magnitude older. There are at least five models for its age, but the weighted mean of these models puts the age at 12.94 billion years, thus giving the earth about 8 billion years to coalesce into the nasty, raging bit of heat that cooled to what we know and love now. If you do the dimensional analysis here (as I have done so often above), you get a universe that has been in existence creating stars and galaxies and solar systems and planets and moons and asteroids – and that continues to do all of those activities VERY actively right up until today – you get a universe of 408,075,840,000,000,000 seconds (408.1 quadrillion seconds). The universe has been in existence, plus or minus 2.3 billion years or so (see the link above) for 162,399,598.4 average American lifespans (one hundred sixty-two million three hundred ninety-nine thousand five hundred ninety-eight point four lifetimes).

Why have I taken you through a journey from Planck time to the age of the universe? To suggest two thoughts:

  1. When humans try to imagine events in time, all of us start getting a little foggy about the whole business when it exceeds one of our average lifespans; even then, it is a rare twenty-year-old that can imagine what it means to be forty or sixty or eighty and the eighty-year-old increasingly feels that everything happened “as if it were yesterday.”
  2. While I have divided up time into fractions of seconds at one end of the scale (the Planck time) and quadrillions of seconds at the other end of time, time is not a series of discrete events; it is continuous and seamless. If one divides a Planck time by another Planck time, the fraction of a second gets shorter – it is about 1×10-89 seconds. One can keep doing this – infinite divisibility – and never reach the continuous nature of time; it will always result in smaller and smaller fractions of time with seamless continuity of the asymptote.

It is entirely possible that we are at the measurement limits regarding the start of our universe. Our current measurements are “birth-of-universe-dependent,” that is, the phenomena that we measure to determine its age are all related to the birth of this universe, the one in which we are a tiny particle orbiting a tiny sun in a tiny solar system in a huge galaxy, which is one of countless huge galaxies (we keep on finding more galaxies) that comprise the universe as we know it SO FAR. Stephen Hawking currently hypothesizes that our universe is one such event in a multiverse. Consider a near-infinitely dense point somewhere in space-time (a “singularity”). From time to time, the density becomes too dense for the singularity to contain it and it “burps” out superfluous matter into space-time, but not in the plane and/or dimension of our universe. Sometimes, these burps are tiny and are reabsorbed by the singularity, but sometimes a new universe of some magnitude buds off and starts expanding. For additional erudition on this idea, please watch the following videos:

and/or

This is heady stuff and nearly impossible to understand, except through metaphor and analogy, without the help of advanced mathematics and profound amounts of deep thought (I am a mere chemist and find that I am boggled by these concepts, but I will not deny their allure (p.s. a mere chemist is different from the mythological mer-chemist)).

I will not get into how long this, our, universe is likely to exist. It is an imponderable but is being pondered. Let’s leave the future to those who speculate on those matters (cosmologists and physicists).To conclude, time is a dimension that is infinitely brief (or continuous) and infinitely long (or continuous). Dividing it into human events is convenient, but none of us should pretend that we understand it except by comparing it with events in our own lives. This is not always true; anthropologists, paleontologists, cosmologists, physicists, geologists live on a timeline that, by nature of their study, makes more sense to them and is relatively unlimited by average lifespans and birthdays. We should be humble when we consider the enormity of what has been observed and consider the enormity of what has been observed and consider carefully what is known while allowing that we are not done observing and trying to learn and probably will never finish unless we cease to exist altogether.

Clock

Drip…

Drip…. Drip…. Drip….

Two things happen with each drip: (1) the water falling from the roof of the limestone cavern, from the carbuncle-sized protrusion pointing towards the floor, leaves some of its soluble calcium carbonate behind; (2) the water hitting the tiny finger of wet stone on the floor of the cavern gets a brand new coating of fresh calcium carbonate added to all the previous layers that have landed there, a micron-thin slice of water with a few accreting granules of calcium carbonate each drop.

Drip…. Drip…. Drip….

Another drop, then another. Over the course of the year, perhaps 0.05 millimeters (mm) will be added to the ceiling pimple of wet stone, and another 0.05 mm to the floor finger. Or maybe there is a good bit of flowing water in this cave and the ceiling and floor protrusions will grow up to 3 mm a year. The average growth rate is estimated at about 0.13 mm/year. At that rate, the tiny finger will push skyward (although the only sky it may ever know is its mirror image growing down from above) slowly, ever so incrementally, until in in 164,123 years it has grown to the size of the tallest stalagmite currently known in the world, a stalagmite 70 feet in height located in Vietnam.

Cut a stalactite or stalagmite open and you see the additive process displayed – a portrait of how it came to be, much like the rings of a tree show its age, although in the case of these cavern formations, it shows patterns of fast and slow growth, changes in mineralization of the water, droughts and floods, a time-lapse photograph of what used to be and what is. In this phenomenal cross-section of a stalactite, the water was imbued with manganese carbonate (rhodochrosite), a mineral that often has a pink or red color. At some point in the distant past, this was a cluster of tiny white pimples pointing towards the cavern floor when, for some reason, the mixture of carbonates changed to favor manganese, the water continued to drop ever so slowly, and this family of stalactites was frozen in time.

The_Childrens_Museum_of_Indianapolis_-_Rhodocrosite_stalactite

Of course, these are simplifications; stalactites and stalagmites sometimes grow briefly, then the water course diverts and they remain short for the rest of time, or they grow in sheets and curtains if the water spills like a slow waterfall seeping through the earth above. These fascinating growths take their time, though, growing drop-by-drop, fractional bit-by-bit, until they are magnificent in their dark realms, secret until found by lanterns and humans poking through a slot in a wall behind a curtain of shrubs.

Labeled_speleothems

Slowly

Depth

Want to visit another planet? Go deep. The diversity – and strangeness – of life in the oceanic depths challenges the most fertile imaginations found in fantasy and science fiction. Bioluminescent jellies signal to their prey. Angler fish dangle a glowing morsel just above their enormous, needle-toothed jaws. Creatures both beautiful and, to our dry-land eyes, frightening. But life abounds.

When I was in middle school (quite a long time ago), I found a book in our small town library called “The Abyss.” I don’t know who authored it and cannot find it on the enormous number of websites that might reveal it to my own increasingly abyssal memory, but it was mesmerizing for a 12-year old. Full of fascinating, real-life monsters that glowed. It even had bioluminescence science fair experiments, although with reagents I could not readily obtain. While we have a huge universe spread before us in every upward direction, we understand so little of what we have on earth.

Depth

Bones

Before we started leaving our bones around to intrigue anthropologists a few billion years later, there were the cyanobacteria, which left stromatolites – precipitated calcium carbonate deposited in layers – as well as their distinct chemical footprints. Fast forward tens of hundreds of millions of years, breeze past a huge fossil record of living things large and tiny, plant and animal, bacterial and viral, and we start seeing remnants of creatures  eerily similar to ourselves.

Between 7 and 6 million years ago, the skeletons left behind were different from the great apes who also occupied east Africa. Somewhere around 2.4 million years ago (give or take a couple hundred thousand years), Homo habilis and Homo rudolfensis became distinct from the remnants predominant before then. Around 2 million years ago, the bipedal Homo erectus was living and dying in the region. Around 850,000 years ago, Homo heidelbergensis distinguished themselves. Modern humans – Homo sapiens – crept into the picture around 200,000 years ago and have been improving on the original model every since, albeit slowly. What I’ve glossed over above is actually improperly abbreviated. Read the linked sites for more information. It is an astonishing story and one that deserves consideration by every one of us.

Given that humans started documenting themselves around 5,000 years ago and can only imagine our lives much before that, we must pay attention to the remains our truly ancient ancestors left us to ponder. The people who study this realm of human knowledge proceed cautiously, carefully, trying to make rational decisions about the remains they find. It is better to listen to their stories and read their research than it is to dismiss – or ignore – this fascinating, unimaginably long and incredibly complex process outright. While no single book, documentary, research study or perspective should be accepted without careful analysis, Dr. Donald Johanson has provided an estimable contribution through the website Becoming Human.
The Things We Leave Behind

Frail

How much strength do you have in reserve? How much resilience to difficulty? When does a torrent of potential injury turn into actual harm? Where does resistance collapse into capitulation? Why are you weaker than I am or, conversely, why am I weaker than you? What insult makes us laugh or tips the scales into tears and decompensation?

The lucky among us face few true tests of these dimensions during our lives, but there are few of us who are lucky. It may even be that the lucky among us strive to feel stress just to feel, while the unlucky spend every waking minute trying to diminish the rain of blows life can mete out.

Stress and strain are as diverse a set of measures as any in the human experience. Physical stress, so well born by athletes, defeats those of us who have no particular capability to run, leap, pull, punch, throw, swat, jump, crunch, dive, dance, twirl or fly. Mental stress can often be born well by those with no physical ability at all and can bring down the most astonishing Olympian.

By analogy, the following diagram graphs stress against strain. A stress is administered to a system, whether an iron bar or a piece of plastic, a human bone or flesh, a mental grocery list or a math theorem. “Material,” whether synapse, bone or flesh, goes through elastic tests all the time. If the elasticity is exceeded, permanent deformation (or learning, to put it differently and more positively) can occur. However, lurking beyond deformation is permanent injury, fracture, capitulation.

Stress Strain Curve

http://www.cyberphysics.co.uk/topics/forces/young_modulus.htm

The history of life on this planet – and in the universe at large – is one marked by stresses that have crushed some of us, while strengthening others, have imploded stars and created new galaxies, have taken some species to extinction while allowing others to multiply beyond numbering. We are all on the cusp of unendurable weakness, but we strive on.

We are all frail; what can you endure?

Featured Image

Frail

A Brief, Mysterious Biography

I was born in 1953 to people I don’t know and raised by people I wish I knew better. I have an academic background in literature and science and have worked in positions of increasing responsibility for over thirty years in one realm of the healthcare industry.

Biographical note: I was born in 1953 to people I don’t know and raised by people I wish I knew better. I have an academic background in literature and science and have worked in positions of increasing responsibility for over thirty years in one realm of the healthcare industry. I am interested in many areas of knowledge; literature and science (obviously), but also film, art, many types of music, various episodes in our peculiar, shared, often ignored history, political behavior (rather than politics), various religions. I wish there were more time in every day and more days in every life. I have more books than I know what to do with and keep on adding things to my wishlist that I may never get to read, but it is better to be curious than not, alive than dead.

The Water Cycle

The hydrologic cycle is a central phenomenon enabling life on Earth. It is complex on a macroscopic and molecular level and functions interactively with every aspect of our biological, geological, and physical world. Its impact on humanity has anthropological, economic, environmental and social implications that are numerous.

The hydrologic cycle is a central phenomenon enabling life on Earth. It is complex on a macroscopic and molecular level and functions interactively with every aspect of our biological, geological, and physical world. Its impact on humanity has anthropological, economic, environmental and social implications that are numerous.

The Water Cycle

(“Water cycle,” n.d.)

Yet it all starts with one of the simplest of all chemical species – the water molecule. Only 3 atoms in composition, 18 daltons in mass, less than 300 picometers (282 trillionths of a meter) in diameter, its complexity is the subject of numerous books and articles. Under the right conditions, it is a solid, a liquid, a gas, an acid, a base, a neutral atom (although this is rarely true in nature), a ricocheting billiard ball as a gas and/or a component in a complex, flickering lattice of other water molecules in liquid and solid form.

The Water Molecule(Blamire, 2000)

Even with this level of complexity, it is impossible to understand the water component of the hydrological cycle without understanding that water loves to mingle with other molecules. If water encounters a solid ionic compound, like the wide range of salts found in soil, streams, rivers, lakes and oceans, it pries the ions apart and engages them in three three-dimensional ballet of solubility. If it encounters an acid, it becomes the hydronium ion in the process of dissolving the acid; if it encounters a base, it becomes the hydroxide ion in the process of dissolving the base. If it encounters reactive gases, like carbon dioxide or sulfur dioxide or nitrogen oxides, it forms carbonic or sulfuric or nitric acids. If it encounters something that is dry, like the surface of a stone or a clump of clay, it erodes and moves some of it to another location, sometimes near its origin and sometimes far away. If it encounters discrete materials, it breaks them down and mingles with them. If it encounters organic compounds, some of which are non-polar and not attracted to the water molecule, it causes them to form droplets or micelles, which are then swept along by the water. With other organic compounds, such as esters and ketones and alkenes, it reacts with them to produce polar products, which can then react with other organic compounds.

In living cells, water is the elixir in which life happens. If a tree, a cell, a human or a cat encounters water, it is sipped up and used to fortify these water-dependent structures, which collapse and turn to dust without its liquid sustenance. Water carries inorganic and organic ions; it carries phospholipids and amino acids; it carries nucleic acids and sugars; it encourages fatty acids to circle the wagons and create cell walls, across which the cell’s supplies are pumped by active and passive portals that open and close for water and its many friends. It encourages DNA to spiral inwards as the nucleotides bond and the sugar/phosphate backbone prickle outwards into the cell’s aqueous soup. Information could not travel if not for the charged molecules that water helps create and carry. But enough about water the molecule. Let’s consider water, the cycle.

Let’s pretend, for an instant, that water “starts” somewhere and continues through the cycle from this starting point. Let’s pretend it starts as precipitation. Forget for a minute that precipitation starts with clouds and clouds start with evaporation and evaporation occurs because of wind, sun, and atmospheric pressure. Forget for a moment that water precipitates as a solid now and then. Let’s just pretend it rains. What happens when it rains? Droplets of water between 0.02 and 0.25 inches in diameter reach terminal velocity of between 5 and 20 miles per hour and strike whatever is beneath them. Each raindrop is rarely pure water; for rain to occur, the vapor in clouds condenses around “a microscopic particle of smoke, dust or salt” (USA Today). In a fascinating calculation, Bob Swanson, a weather editor with USA Today, provides an estimate of the number of droplets that fall in a storm:

“Assuming an average thunderstorm is 15 miles in diameter. Assuming a circular base of the storm, the area of the storm’s cloud base is about 175 square miles. Now let’s assume that .25 inches of rain falls from the storm. This yields a total volume of rainfall of around 175 billion cubic inches. Now if we assume a spherical raindrop, the volume of an average size drop would be about 1/10,000th of a cubic inch. Dividing the total rainfall by the volume of an average raindrop gives a total number of raindrops around 1,620 trillion.”

When one also assumes that each droplet reaches terminal velocity, there is tremendous energy unleashed in a storm. Then think of all the storms that happen and all the energy from all the storms. This is a lot of force dropping out of the sky! When old leaves are struck by raindrops, they are ripped from their homes, becoming compost for new life. If dead things are struck by water, bacteria and molds help decay the creature and turn it back into nutrients, parts of other cycles of nitrogen and carbon and sulfur. If a rock or soil is struck, small amounts are displaced and move away from their source. For evidence of what rain can do, examine the Badlands of South Dakota or the gaping tear known as the Grand Canyon or the alluvial plains of South and North Carolina – created from Appalachian precipitation on mountains that were once five times as high as they are now. Yes, some of this was due to the action of rivers, but the rivers were replenished by rain.

Raindrops

(PBroks13, n.d.)

Different sizes of raindrops:

  1. A) Raindrops are not tear-shaped, as most people think.
  2. B) Very small raindrops are almost spherical in shape.
  3. C) Larger raindrops become flattened at the bottom, like that of a hamburger bun, due to air resistance.
  4. D) Large raindrops have a large amount of air resistance, which makes them begin to become unstable.
  5. E) Very large raindrops split into smaller raindrops due to air resistance.

One way that water re-enters the hydrologic cycle is through watersheds, defined as “a land area whose run-off drains into any river, stream, lake or ocean” (USEPA, June 1998, p. 1). Run-off doesn’t only occur on the earth’s surface, though. Of the 332 million cubic miles of water on our planet, 97% of it is salt water and approximately 1.7% of it is groundwater (USGS); only 46% of this is fresh water. This is replenished by seepage into the ground from the various types of precipitation. If we were to dig a perfect hole in the ground, we would find the upper layers a mixture of air and water, but lower layers would become increasingly wet. Eventually, we would reach a level where water occupies all of the space between grains of sand and gravel. This level is called the water table.

Water Table(“Water table,” n.d.)

Of course, some of the water all courses down streams to rivers and rivers to lakes and lakes to seas and oceans. Some of the water that enters streams and rivers and lakes and oceans weeps out of the ground into these bodies of water, depending on the relative elevation of the water table to the bodies of water in the area. Some of the water in the water table is pumped up for use in homes and factories as well.

The water cycle really gets complex when precipitation falls on and interacts with man-made phenomenon, like roads and highways, or human industries like oil refineries and coal-burning power plants and waste pools for cattle and swine and agricultural fields full of pesticides and herbicides and fertilizers, or human by-products like landfills or untreated waste streams from storm drains. When water, this remarkable molecule, plunges to earth and mobilizes the products of human industry, the entire water cycle becomes contaminated in the process. Water takes our waste and pollutes the rivers, lakes and oceans, creating imbalances in nutrient cycles and killing creatures that depend on a balance between water and salts, nutrients and energy to live their normal lives. Water releases volatile organic compounds from human industry and they become part of our atmosphere. Water mixes with the sulfur and nitrogen oxides and precipitate back to earth as strong acids that change the equilibrium state that nature requires for its magic.

References

Rights for use of the raindrop illustration are granted by Pbroks13 as follows: “I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.”

PBroks13. (Artist). (n.d.). Raindrop. [Print Graphic]. Retrieved from http://en.wikipedia.org/wiki/Rain

Bell, J.A. (2005). Chemistry: A project of the American Chemical Society. New York: W.H. Freeman and Co.

Flynn, D.J. (ed). (2009). The Nalco water handbook (3rd ed.). New York: McGraw-Hill Co.

Jacobson, M.C., Charlson, R.J., Rodhe, H., Orians, G.H. (2000). Earth system science. San Diego, CA: Academic Press.

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