Friday, September 1, 2017

Texas Torrents—and Insurance’s Perfect Storm

Hurricane Harvey dropped nearly 52 inches of rain on southeastern Texas and beyond. Standard home and business insurance policies exclude flood damage as a named peril. Few people are covered by separate flood insurance policies. And key parts of the National Flood Insurance Program are set to expire on September 30, unless....  

On August 30, Tropical Storm Harvey blasted through the single-storm total rainfall of any storm ever recorded in the continental United States: 51.88 inches over Cedar Bayou. All equivalents to the 24.5 trillion gallons dumped onto Texas and Louisiana are staggering. That volume exceeds Houston’s average annual rainfall in less than a week. It approximates 15 percent of the volume of Lake Erie. That’s a year’s flow over Niagara Falls. It's enough to cover the entire state of Arizona a foot deep.
Thousands of square miles were flooded by Hurricane Harvey. More than 80 percent of these homes are not protected by flood insurance. Credit: The Washington Post

The nation’s attention is riveted on Houston as the fourth largest city in the nation and the center of the country’s petroleum industry. But as history reminds us: Harvey is flooding areas far beyond Houston. It is also devastating the lives of people in surrounding areas of Texas with three and four feet of water: in a fateful echo of the 1913 flood, Dayton, TX was deluged with an unfathomable 49.23 inches. Louisiana and neighboring states were also hard hit—including locations impacted by Hurricanes Katrina and Rita almost exactly 12 years ago (see “How Does Hurricane Harvey Compare with Katrina?” and “Katrina + 10: Once and Future Disasters”).
Harvey dumped more than four feet of rain on Dayton (!),
Texas; see video on YouTube

Hearts and prayers go out to the hundreds of thousands of people displaced from homes and workplaces with nowhere to go as the water itself has nowhere to go. Already talking heads are estimating recovery will take years—as indeed it did after Katrina. 

However, if shivering flood sufferers are consoling themselves by clinging to a warm hope that their homeowner’s or business insurance will make them whole, the chilling reality is: some things have not changed since 1913. They may be dead in the water. 

Scary facts to contemplate:

Home and business insurance policies do not cover flooding 
Indeed, typical policies almost always have a specific exclusion not only for flooding but for any type of groundwater intrusion—including from such ordinary causes as backed-up sewer mains or snow melt from high drifts piled against foundations. Obtaining protection against any source of groundwater requires a separate flood insurance policy. 

One reason private insurers eschew covering flooding on their own is that, unlike such disasters as fire that often affect only one or a few houses in a residential area, flooding can devastate square miles at a go: as of August 31, Harvey has inundated nearly 29,000 square miles with at least 20 inches of rain, and many times more area at lesser but still monumental volumes of water. Thus, major floods represent a terrific risk to an insurer. 
Harvey inundated tens of thousands of square miles to
unprecedented depths. Credit: The Washington Post 

Recognizing that, in 1968 the U.S. government instituted the National Flood Insurance Program (NFIP), now managed by the Federal Emergency Management Agency (FEMA). The NFIP makes federally backed flood insurance available in communities that agree to adopt and enforce floodplain management ordinances to reduce the community’s (and thereby also the nation’s) overall risk of future flood damage. NFIP coverage is up to $250,000 for the structure and $100,000 for the contents of a home.

To ascertain flood risk in various locales and to price premiums, the NFIP conducts surveys and studies along coastlines, waterways, and other places to identify areas prone to floods or flood-related hazards (such as storm surges, tidal waves, mudslides, flood-induced erosion, etc.). Such flood risk zones are plotted on Flood Insurance Rate Maps (FIRMs). These maps focus on identifying Special Flood Hazard Areas (SFHA): areas having a 1% or higher chance of flooding in any given year, also stated as being at risk of flooding during a “1-in-100-year flood.” 
Harvey has been rated as a once-in-a-
millennium event. Credit:
The Washington Post

The only homeowners required to obtain a flood insurance policy are those who choose to live in a SFHA—that is, within the area of a hundred-year flood. For better or worse, flood insurance for everyone else is optional (and most agents don’t even discuss it with clients unless asked, and might pooh-pooh it if asked). 

Because flood insurance is not universally required like other homeowner and auto insurance, people underappreciate their true risk—indeed, perhaps are lulled into a false sense of security that they have no risk.

Woe to them, because…

…flood risks are greater than most think
Many people did not take probability theory in high school math (or don’t remember it if they did). So here’s an eye-opening refresher news flash: a 1-in-100-year flood is virtually guaranteed to occur far more often than once a century. Indeed, the way the mathematics of probabilities works out, during the course of a 30-year mortgage of a property in a SFHA, there is a 26% chance the home will be flooded. That’s better than one chance in four, folks. Them’s betting odds. 

A similar situation also holds true for supposedly lower-risk regions, such as those designated as 0.2% zones (a 1-in-500 flood). And nothing about the odds indicates when. Indeed, two 100-year or 500-year events could—and have—happened in back-to-back years: Harvey itself is Houston’s third 500-year (or greater) flood in three years after its two Memorial Day floods in 2016 and 2015.
Two dozen so-called 500-year floods have befallen various
places in the United States since 2010.
Credit: The Washington Post
The rainfall intensity of Harvey is now rated as a 1-in-1,000-yearflood event for Houston—that is, a flood of such great magnitude as having just a 0.1 percent chance of happening in Houston in any year. 
Upshot: either because of ignorance of the actual risk or of the necessity for a separate policy or because the insurance is optional, only a meager 12 percent of U.S. homeowners nationwide carry flood insurance. The percentage is a bit higher in the south (especially in Florida), but even in flood-prone Houston more than 80% of homeowners have not seen fit to take out flood insurance. 

That means that for four out of five Houstonians, their Harvey-ravaged homes are likely a dead economic loss. If they choose to rebuild, it could mean bye-bye to retirement savings…

(FWIW, tornadoes, high winds, and hail may be covered by standard homeowner policies, depending on the policy and the insurer, but earthquake damage is also often excluded; the only way to know for sure is to check your policy. It is also important to ensure that the limits to your coverage are high enough to realistically cover the cost of repair or replacement.)  

Key parts of the National Flood Insurance Program are due to expire
Unless reauthorized or extended by Congress, come September 30 (2017), the NFIP can no longer write any new flood insurance policies; moreover, 
existing policies would continue only until the end of their one-year terms, and then terminate. The authorization of appropriations to continue mapping flood hazards also would expire, including any programs to update older flood maps to take into account the effects of development or climate change. And the authority for the NFIP to borrow funds from the Treasury—to, among other things, make good on claims submitted from Tropical Storm Harvey—would be reduced from $30.425 billion to $1 billion. For details, see the July 25, 2017 Congressional Research Service report R44593 Introduction to the National Flood Insurance Program (NFIP).
Top 10 flood insurance payouts.
Credit: Insurance Information Institute

But that’s not all. Long-term, many experts are convinced that the current structure of the NFIP needs thoughtful comprehensive reform (for example, see U.S. Government Accountability Office, report GAO-17-425, Flood Insurance: Comprehensive Reform Could Improve Solvency and Enhance Resilience, April 2017). In part because of the huge multi-billion-dollar hits of Hurricanes Katrina and Rita in 2005 and of superstorm Sandy in 2012, which dwarfed more “average” losses in other years, the NFIP is now in significant debt for the payout of claims and other expenses, because premiums are insufficient to cover losses. As of March (2017), the NFIP owed the U.S. Treasury $24.6 billion. 

Existing premiums do not reflect the full risk of actual losses to floods, especially in the context of rising sea levels and trends toward increasing intense rain events—a shortfall that increases the federal exposure to risk. At the same time, affordability of premiums has been a political hot potato, especially from people who want or need to stay in an SFHA for whatever reason: because it’s all they can afford, or because they enjoy a great view, or because the property has been in the family’s hands for generations, or simply because they do not grasp the magnitude of their actual physical risk. 

Sea level rises, coastal cities sink, rainfalls intensify
Houston, the Gulf Coast, and much of the entire east coast is facing a triple whammy as the result of measured and predicted climate change.

First, global sea level is rising—and quickly: 3.4 mm per year. A few silly millimeters may not sound like much, but that rate amounts to 1.3 inches per decade worldwide. There are two causes, both stemming from the warming of the planet: first, the oceans (which are absorbing 90 percent of the warming) expand as the result of absorbing thermal energy (thermal expansion is how non-digital mercury or liquid fever thermometers work); second, the volume of water in the oceans is increasing as Arctic and Antarctic ice sheets melt.
Just since 1993, in less than 25 years, sea level around the entire planet has risen 3.4 inches, Credit: NASA

Second, there’s an increased likelihood of more powerful hurricanes with higher wind speeds. Moreover, as warmer air can hold more moisture, even milder tropical storms are likely to bring increasingly intense rainfalls.

Third—and less appreciated, but in some places more significant—the land on which many coastal cities are built is subsiding (sinking) as the result of the pumping of fossil fuels and groundwater from underground reservoirs. When the fluids are removed, the overlying ground layers sink lower, exacerbating the effects of flooding from higher sea levels. Nowhere is that as pronounced as in the cities of, wait for it, Houston and Galveston

A Hurricane Harvey is not necessary for a disaster
Even before Harvey, insurers have been growing increasingly concerned about this juggernaut “perfect storm” confluence of events. In April (2017), the American Academy of Actuaries concluded: “There is an increasing awareness among various constituencies (regulators, legislators, consumers, insurers, real estate agents) that too many uninsured homes are subject to devastating losses from flood events, and the NFIP alone cannot solve the problem. This is true today, and will be even more true if changing conditions result in rising sea levels and/or more extreme rainfall events in the future.” (The National Flood Insurance Program: Challenges and Solutions, April 2017, p. 77)
Far less rain than Harvey dropped on Houston can cause record flooding in colder northern regions of the nation. A century of weather data indicate that intense rainfall events over the Ohio Valley and Midwest are increasing both in frequency and intensity. Because the Easter 1913 storm system brought the flood of record to Indiana and Ohio, data from it set a benchmark for the question “how bad could ‘extreme’ become?” (see “Benchmarking ‘Extreme’”) Credit: NOAA; Trudy E. Bell
It is time for clear-sighted recognition of the reality of the stark words of FEMA itself, “Everyone lives in a flood zone.” 

Floods can happen in unexpected places—even places where rainfall is not intense, or even is completely absent. In the U.S. Southwest, for example, flash floods from cloudbursts in distant mountains can rush through downstream desert areas that haven’t seen a drop of rain (that’s why campers should never set up a tent in an arroyo or dry stream bed even if the banks look like an attractive shelter from wind). Flash floods in downstream dryer areas can also happen with springtime melting and bursting of upstream ice dams. In urban areas, the construction of impermeable surfaces such as parking lots and pavements increase the speed of runoff and impede the absorption of rains into soils—and the hardening of riverbeds or coastlines with riprap (concrete blocks) can redirect flooding onto neighboring lands. 

And as anyone who has endured a household flood can attest, even a little bit of water can wreak thousands of dollars in property damage: just imagine what flooring, furniture, and electronics would need to be repaired or replaced in your own home if your living room and bedrooms were ankle deep in muddy floodwater contaminated with sewage and chemical toxins. Moreover, water has so much mass that even two feet of rushing water can sweep away a car (as well as ruin the engine and interior).
Square miles of flooding in Dayton, Ohio, from the 1913 flood. Then, as now, homeowner insurance did not cover flooding, so the flood victims on the hilltop in the foreground were likely watching the drowning of their life's savings. Credit: Dayton Metro Library

Upshot: most of us are at greater risk of financial loss from flooding than we recognize. Even though no one anticipates having a house fire or getting into an auto accident or needing surgery, most adults recognize that the risk of such events is not zero, and that any such event could be financially catastrophic (assuming we lived); so we routinely carry homeowner, auto, and medical insurance to protect ourselves against financial ruin. Even if we never make a claim, we rest easier at night with peace of mind—and if disaster falls, we are thankful that our loss is limited to just a deductible. 

Yet somehow we don’t recognize our same non-zero physical and financial risk to flooding—even if we live near coastlines or other water, as much of the nation does. Strong economic and risk-reduction arguments could be made in favor of encouraging all homeowners, renters, and business owners to mitigate their risk to floods as they already do against other risksboth to protect themselves and to ensure the viability of national flood insurance while keeping premiums low. 

©2017 Trudy E. Bell

Next time: Desperate Medicine

Selected bibliography
Bell, Trudy E., The Great Dayton Flood of 1913, Arcadia Publishing, 2008. Picture book of nearly 200 images of the flood in Dayton, rescue efforts, recovery, and the construction of the Miami Conservancy District dry dams for flood control, including several pictures of Cox. (Author’s shameless marketing plug: Copies are available directly from me for the cover price of $21.99 plus $4.00 shipping, complete with inscription of your choice; for details, e-mail me), or order from the publisher.

Tuesday, August 1, 2017

The tornado and the eclipse(s!)

Three reasons for visiting Makanda, Illinois: 1) retracing the path of the 1913 Easter Monday tornado, 2) witnessing the upcoming total eclipse of the sun on August 21, and 3) witnessing another total solar eclipse on April 8, 2024.

[Inspired by this remarkable geographical coincidence, this historical research blog will take an unusual foray into an astronomical topic of intense current public NEW! total solar eclipse report: see section "Mad dash to Wyoming" near bottom of post]

Don’t let anyone convince you otherwise: the difference between a 99 percent partial solar eclipse and a total solar eclipse may be just 1 percent of the sun’s surface, but it’s 100 percent of the experience. And that difference is what makes some people spend thousands of dollars to pursue the moon’s shadow to the remotest regions of the globe, just to experience a few minutes of totality. I should know: I’ve chased five (5) total eclipses of the sun to Mexico, the Arctic, the Sahara, the South Pacific, and Montana.
The upcoming total solar eclipse
of August 21, 2017, will pass
right over Makanda, Illinois—
a town devastated by a fatal
1913 tornado on Easter Monday,
March 24. Credit: NASA

Through sheer dumb luck, the total eclipse of the sun coming up midday on Monday, August 21, 2017—a celestial event that’s been so widely publicized over the past few months that literally millions of people are planning to congregate along the 70-mile-wide path of totality from coast to coast from Oregon to South Carolina—happens also to pass over a rural region in southern Illinois just a few miles southeast of Carbondale, Illinois, a region that in 1913 was sent spinning during the Great Easter storm system. 

‘The winds of destruction’
Easter weekend 1913, the front pages of major newspapers across the country widely reported the devastation and fatalities of the EF4 Good Friday tornado that ripped through Lower Peach Tree, Alabama, and the similarly violent Easter Sunday tornadoes that roared through Omaha, Nebraska, and Terre Haute, Indiana.

But buried on the back pages of national papers are brief squibs documenting how the monumental Great Easter 1913 storm system loosed a dozen other tornados that roared through half a dozen other states over several days that fateful long Easter weekend. Only rural local newspapers reveal the full story of lives snuffed out or ripped apart, where everyone knew everyone else so well that the geographical locations of individuals’ homes did not need to be specified to readers the next morning.

Path of the Makanda tornado, plotted from accounts in four southern Illinois newspapers, was about 25 miles long.

One of them was the Makanda tornado. It first touched the earth just west of Makanda (some five miles southeast of Carbondale) around 7:20 PM near nightfall Easter Monday evening, March 24. Amid an intense crashing lightning storm, terrifying low black clouds, and torrential downpour, roof timbers of the Walker house collapsed onto the marital bed, killing Mrs. Walker and breaking the legs of her husband. At the Patrick house, 11-year-old Reva was ejected 250 yards, her body an unrecognizable bloody mass when finally discovered by her seriously injured parents.

After demolishing at least three dozen houses in Makanda, the tornado hurled some 21 cars of the Illinois Central Freight No. 51 into a ravine near Boskeydell, destroying the cargo of bacon, automobiles, and other merchandise, and tearing up a quarter mile of double track. The engineer, who miraculously escaped with little injury, recounted how he felt the engine lift up two feet before dropping back onto the track.

Although the Makanda tornado made
the front pages of local southern Illinois
The Herrin News and The
Marion Evening Post, it was back
page news in national newspapers.
Then, the “winds of destruction” (in the words of the Murphysboro Republican-Era) roared off northeast for another 25 miles, alternately leaping up and swooping down to the ground. En route, it claimed a third life—that of 8-month-old Mildred Altman in a Big Muddy mining camp, when she and her young parents were blown from their home when it was destroyed. Near the end of its path, the tornado wreaked almost as much destruction in Whiteash as in Makanda.

Thomas Grazulis in his classic 1991 two-volume reference work Significant Tornadoes rates the Makanda twister as an F-2 (equivalent to an EF-2 in today’s extended Fujita scale). But he did not appear to find information on its size. Several southern Illinois newspapers, however, were very specific that its path of destruction, depending on locale, ranged in width from 100 yards to a quarter-mile. Based on that data compared with the other Easter Sunday tornadoes that visited death and destruction on Nebraska and Missouri that Grazulis estimated to be EF-3 and EF-4, I can’t help but wonder whether the Makanda tornado was at least as violent as an EF-3.

In the mournful days that followed, the residents of nearby Carbondale, thankful at their own lucky escape, donated to a relief fund started by that larger town’s Daily Free Press. Within days, the fund had raised more than $500 (equivalent to maybe $10,000 or $15,000 today) for the tornado victims—at least a start for emergency care.

The “Great American Eclipse,” August 21, 2017
Now for something completely different in this historical research blog…

The earth is the only planet in the solar system from which it is possible to see a total solar eclipse: humans are extraordinarily lucky that, as seen from earth, both the moon and the sun look nearly the same size. And by a remarkable coincidence of geography, not one but two total eclipses of the sun will be visible from Makanda, Illinois—one this month and one less than seven years later!

Makanda will be crossed by the path of totality for not just this August 21, 2017 total solar eclipse, but also for another one less than seven years later, on April 8, 2024. And Carbondale, Illinois, (the biggest town near Makanda) is planning a big celebration for them both. Credit:
In recognition of that geographical coincidence, here are a few simple “eclipse appreciation” tips from a totality junkie for what has been dubbed the “Great American Eclipse.” (In case you’re suffering whiplash by the leap from 1913, FYI by profession I am a science journalist, writing frequently about astronomy and telescopes—indeed, for my first two years as an undergraduate, I was a physics major intending to become an astronomer before I ultimately switched majors to history.)

In the simplest terms, a solar eclipse happens when the moon comes directly between the sun and the earth, so that the moon’s shadow sweeps across the earth as the moon travels in its orbit and the earth rotates on its axis. Most solar eclipses are seen as partial—where the moon covers only a third or half the sun’s surface. The sun is so bright that most people (unless told ahead of time) likely wouldn’t notice any dimming effects—or would likely just think a cloud had passed in front of the sun—until more than 90 percent of its light is blocked.

But if you happen to be in a location near where the umbra—the darkest center of the moon’s shadow—sweeps by, you can see the eclipse as total: the moon blocks ALL the light from the sun’s brilliant surface. And that is when, for a precious few minutes, the magic happens.
On August 21, the moon will come directly between the earth and the sun. Credit: B&H Photo
Most solar eclipse websites correctly emphasize the importance during the partial phases of not looking directly at the sun to avoid irreversible damage to the retina, unless you wear ISO-approved special sun-filter eyeglasses (which are widely available for cheap or even for free from astronomy clubs and other outlets).

Another even safer option is watching the partial phases by projecting an image of the sun from a pinhole or cheap lens onto a screen. The hole in the side of the tube is big enough so several people can view the sun’s image on the screen at the same time.
Make your own totally safe sun viewer to watch the partial phases of the August 21 solar eclipse! This crude but utterly safe solar projector cost only about 50 cents in materials: half a pair of +1.00 diopter reading glasses from Dollar Tree. I followed the basic instructions given at this excellent web page (adapting to the fact that their viewer was rectangular and mine triangular). The left photo shows the whole viewer, which is about 40 inches long and can be propped up against any convenient object. The top right close-up picture shows the arrangement of the single eyeglass lens at the top of the viewer; when the sun’s crescent gets thin and dim, the small aperture (a circular hole in an index card from a standard hole punch) can be slid away to expose a larger half-inch hole that admits more light. The bottom close-up picture shows an image of the sun as projected onto a screen made from a white index card at the bottom end of the viewer.

Once the eclipse becomes total, then for up to a precious two-and-a-half minutes (depending on how close you are to the center line of the path of totality), it will be safe to look up without protection and behold the sun’s corona—its ghostly, feathery, pearly outer atmosphere—haloing the black disk of the moon.

The bizarre, the strange, the unexpected
Don’t despair if you don’t have sun-filter glasses or a solar projector. Or even if you do, don’t limit yourself to looking just at the sun. You can still watch the crescent of the sun get narrower and narrower if you keep aware of your surroundings—especially when the sun is getting more than 90 percent covered. 

Curl your forefinger against the base of your thumb to form a pinhole small enough to project an image of the thin crescent sun onto the palm of your other hand. Or cross the spread fingers of one hand over the fingers of the other to project a grid of crescents onto the ground. Or look on the ground under a leafy tree to see a host of crescents from sunlight through the leaves—or crescents on a woman’s shoulders projected through the loose weave the brim of a tropical straw hat.
Shadow of a tree on the siding of a house revealed hundreds of solar crescents photographed by Ed Morana in 2012 when the thousands of leaves formed many tiny pinhole projectors (get to a bigger version of this photo by scrolling down to near the bottom of this Vanderbilt University page)

In the few minutes just before and after totality, you may become aware of a flickering out of the corners of your eyes. If so, keep alert for the still-mysterious shadow bands: long, faint, low-contrast stripesof shadow that run over the ground, scurrying over people and trees, giving one the sensation of being at the bottom of a sunlit pool with shadowy ripples. FWIW, in my experience, shadow bands have been more evident if an eclipse happens on a sparkling clear day and almost nonexistent on a hazy or cloudy day.Some videos of shadow bands in recent eclipses appear on YouTube.
Drawing of shadow bands during
the 1870 total solar eclipse in
Mabel Loomis Todd’s
1894 book
Total Eclipses of the Sun.

The last few minutes right before totality, you can watch the landscape dim almost from moment to moment, darkening to a steely or even teal green—a shade of sky I’ve never seen in any other natural setting. I’ve never had the luck to be around animals or birds as totality approaches, but numerous people have recounted how wildlife instinctively prepares for sleep as if night were approaching.

When the last 1 percent of the sun’s brilliance is finally blocked by the moon, totality drops with astonishing swiftness—like a cloak or blanket falling across the earth. This is the climactic moment for which eclipse-chasers wait and plan and dream for months or years. Overhead, the sun’s silvery outer corona glows in pearly glory, its gossamer shape and structure differing markedly from one eclipse to another—sometimes compact and round, sometimes broad and spiky.

But if there are partial clouds, don’t despair. Some clouds can give rise to spectacular effects.

As the sun gets increasingly covered, keep an eye toward the west-northwest—the direction from which the umbra (the dark central portion of the moon’s shadow in which it is possible to see a total solar eclipse) will be racing toward you. For the south Pacific eclipse, I was on the deck of a cruise ship on a partly cloudy day. As the umbra raced closer, clouds in the west began to be tinged with sunrise pink—which spread across the western horizon and darkened rapidly like a fast-moving thunderstorm. There was something thrilling and inexorable about the spreading, darkening clouds that made me want to run before the shadow, like running from ocean waves rolling toward a beach. One person likened it to a “visible wind.”
In the right environment, clouds can enhance
the beauty of an eclipsed sun, as shown
in this photo of the 2016 eclipse by
astronomer Dennis Mammana using just
an iPhone {scroll down to near the end of this page)
Moreover, since the moon’s umbra is relatively small—only 70 miles across for this eclipse—during totality you may see its edges as soft yellows, oranges, and reds surrounding the horizon for all 360 degrees. The colors may be most evident if you are atop a hill with no buildings or trees blocking the horizon.

Hands down, the most remarkable experience I had with clouds was an early morning winter eclipse when the sun was rising over Montana snow. The sky was filled with thin cirrostratus clouds—high, translucent clouds of ice crystals—that washed out the delicate details of the corona during totality. Those winter ice clouds, however, created a multicolored rainbow-like halo circling the partially eclipsed sun.

But the real jaw-dropper was at the end of totality. As the umbra raced eastward, the eastern horizon darkened and the western horizon lightened. Then suddenly—because the high thin clouds acted as a rear-projection screen—the clearly defined trailing edge of the moon’s shadow lifted up off the western horizon and rose across the sky. And the instant the umbra’s edge transited the sun, the diamond ring broke out—that dramatic instant when the first brilliant edge of the sun just begins to peek through mountains and valleys along the moon’s edge, ending totality.

There’s a whole body of psychology on “peak experiences”—and it’s undeniable that to many people observing a total solar eclipse is often a fantastic physiological high. People’s reactions range from euphoria to tearful longing. I’ve been flooded with one or the other during each of the five eclipses I’ve beheld. It’s one of the reasons I want my daughter to experience this one. 

So on August 21, get yourself into the path of totality and look up: give yourself time simply to watch our magnificent universe unfold.

PROJECT: Make your own solar eclipse!
In the upcoming August 21 solar eclipse, the vast penumbra (from within which partial phases can be seen) will engulf the entire country—but the eclipse can be seen as total only from a narrow path where the 70-mile-wide umbra sweeps from west to east. But what are the penumbra and umbra? After all, isn’t a shadow a shadow? Why can’t the eclipse be seen as total from everywhere?
Neat GIF from NASA shows how the large penumbra and the tiny umbra (tiny black dot) will sweep across the country on August 21. Credit: NASA
To illustrate the umbra and penumbra during a solar eclipse, I conceived a simple demonstration—which could make a great (non-messy!) project for middle school students.

First, I made a circular “new moon” by cutting out a 3-inch disk of cardboard (I traced a circle around a small Mason jar lid, then cut along the lines; thin cardboard like a cereal box is easiest to cut, but an index card does not work because the disk needs to be opaque enough to block sunlight). Next, one sunny early morning (by 7 AM in late July) when the sun was streaming in through a window across my living room, I stuck the cardboard disk to the window (two loops of Scotch tape sticky side out worked great, as it allowed the disk to be repositioned as the sun moved).
Around 7:30 AM when sun was streaming across my living room, I stuck the 3-inch cardboard “moon” onto the east-facing window at the far left. The shadow of the “moon” cast onto the opposite wall at the far right created an artificial miniature solar eclipse.
Then I looked for the disk’s shadow on a wall or floor across the room. Voilรก! Instant “lunar shadow” in a miniature solar eclipse, complete with darker umbra in the middle surrounded by a lighter penumbra! I was surprised and gratified how well both showed. Also, the sun angle changed fairly fast (as the sun rose because of earth’s rotation), making it possible to observe how the “lunar” shadow changed when it fell onto surfaces at different angles and at different distances from the “moon.” 
Close-up of the shadow of the artificial “moon” some 20 feet away clearly shows a darker central umbra surrounded by a lighter penumbra. (Note that the shadow of my hands with camera smartphone is much sharper, because they were only a couple of feet from the wall.) I deliberately included the light switch sharply focused to demonstrate that the fuzziness of the shadows is real and not just an out-of-focus image.

There really are two types of shadows—and on a sunny day, you have undoubtedly seen both the umbra and penumbra of your very own sun-shadow countless times without realizing what they were. Indeed, the penumbra is what makes the edges of your shadow fuzzy instead of sharp.

The basic reason is simple: The sun is close enough to earth that it has a good-sized diameter in the sky. Thus, every point on the sun—not only its center but also all around its edges—emits light from a slightly different angle as seen from any object on earth. So only the middle of your body blocks the light from all across the sun. But the edges of your body don’t, because the sun’s diameter effectively allows light from different parts of the sun to “wrap around” your body just a little ways.

This is easy to visualize—and to see in a demonstration—if you imagine that the sun emits light only from two separate points on opposite sides of its disk, each casting its own shadow of your body onto a wall: where the shadows intersect in the middle and are darkest, that is the umbra; where each shadow falls alone is the lighter penumbra.

Two halogen desk lights a few inches apart cast two shadows of me on the opposite wall. Where the two images overlap is the umbra. A viewer within the umbra looking back toward me would see that my body eclipsed both lights (the equivalent of a total solar eclipse). But a viewer within the lighter penumbra on either side would see only one light eclipsed (the equivalent of a partial eclipse).

This same thing happens with the moon during a solar eclipse (see diagram). Because the sun emits light from slightly different angles from points all over its entire face, the moon blocks rays from some points without blocking rays from other points. Where all those shadows overlap in the center is the small, dark umbra. It is surrounded by a much vaster halo where rays of sunlight  from other parts of the sun still penetrate the shadows: that is the penumbra.

In addition, the moon is far enough away from earth that its darker inner umbra shrinks to a small cone only some 70 miles wide (for this eclipse), while its penumbra expands to several thousand miles wide. That effect was also illustrated with the artificial “moon” and the real sun, as seen in this last photo.

The farther the moon is from the earth, the smaller the umbra becomes. That was clearly shown when the artificial “moon” shadow landed on my front door, which was about 10 feet farther from the window than the wall with the light switch. The central umbra shrank while the penumbra grew wider.

By the way…
For the August 21 eclipse, a distressing number of websites make misleading claims. Some sites assert it’s the first total solar eclipse visible from the United States for over a century. That’s patently false. There have been close to a dozen. The last was February 26, 1979, whose path of totality swept through the northwest (including Montana, from where I saw it) and then up into Canada. Before that, totality for the eclipse of March 7, 1970 swept across Mexico and up the U.S. east coast. And on January 24, 1925, New York City itself south of 96the Street was inside the path of totality.

What’s actually unusual about August 21’s eclipse is that it’s the first since June 8, 1918, that the entire path of totality across North America falls within the borders of the continental 48 states without also traversing parts of Canada or Mexico.

Regardless, take the kids out of school and cash in a vacation day: a total solar eclipse is totally worth it. Remember, you must be somewhere inside the path of totality to see a total eclipse—and 99% is not, repeat NOT the same as total.

NEW 8/28/17: Mad dash to Wyoming
I was not in Carbondale, IL (which had mixed luck with clouds)—indeed, was in Nebraska. I had originally hoped to photograph the eclipse over the copper dome of the 19th-century Boswell Observatory at Doane University in Crete (where I had been doing some research a few days earlier for my current book contract on 19th-century U.S. observatories) but all weather reports predicted clouds and thunderstorms. The best weather odds seemed to be in eastern Wyoming, more than 500 miles west.
Doane U professor Brad Elder supervising my pouring of molten
speculum metal into a 2-inch mold for a mirror of the type
Isaac Newton used in a small telescope. Credit: Roxana Bell

So at 3AM on Monday, Doane professor Brad Elder and his wife Amanda Kuhl—who two nights earlier had fired up the foundry in their driveway and let my daughter and me pour 2-inch mirrors out of molten speculum metal!—picked us up from our motel and headed west at 80 mph, apprehensive about thick ground fog reducing visibility in the Platte River valley for tens of miles. 

We arrived at Road 12 and U.S. Hwy 85 about 25 miles south of Lusk, WY, about half an hour before first contact, relieved that fog had melted into general haze. Already several thousand campers, SUVs, and cars were lining US 85 with cameras already aimed sunward. Among the hundreds of vehicles, we easily found a spot on a rise only a few hundred yards from the center line of the path of totality, with a clear view to the northwest and southeast, hoping to see the approaching lunar shadow. 
Roxana and Amanda with Karl Esch’s safe solar
viewer after partial eclipse had begun.
Credit: Trudy E. Bell

Brad, Amanda and Roxana had never seen a total solar eclipse (before this one, I was five for five). Although we occasionally glanced upward thru eclipse glasses, mostly we watched the partial phases using an ingenious solar viewer built and shipped to me by a longtime friend and sometime coauthor Karl Esch, who was himself eclipsing in Oregon. 

We all hoped to see the flickering that heralded shadow bands, but saw nothing (in part, I suspect the haze washed them out), but were delighted with the abundance of crescents falling on our shoulders through straw hats. 

Then totality dropped, and we gazed euphorically up into the midnight blue heavens at the feathery white corona surrounding the black disk of the moon It was over far too quickly. 
Brad, Roxana, and Amanda gazing
up at totality (I was lying on the
ground, my knee at left accidentally
in image). Credit: Trudy E. Bell
People in other cars were grinning and in a festive mood and patient in the exiting traffic. We encountered no price gouging reported from other areas. Thunderstorms moved closer and rain was falling when we got back to Crete at 11 PM, 20 hrs and 1,050 miles after our adventure began (although at eclipse time there were only patchy clouds in Crete so some of the city actually did get to enjoy the celestial spectacle). I quipped to Brad that we had averaged 52 mph even when we were standing still gazing awestruck up at the sun! 

Looking ahead now for the next total solar eclipse to cross the U.S. (plus Mexico and Canada) on April 8, 2024—up to 4 minutes and 28 seconds, nearly two minutes of totality longer than this last one at maximum duration! And again, Carbondale is in the path!
©2017 Trudy E. Bell

Next time: Texas Torrents--and Insurance's Perfect Storm

Selected references

I am a contributing editor for Sky & Telescope, so filed a report the night of August 21 about my own mad adventure chasing the moon’s shadow—see reports from all along the path of totality on S&T’s eclipse web page.

Indispensable for helping you plan where to go see the eclipse (and plot what roads you may need to outrun clouds) are two complementary publications by longtime NASA eclipse expert Fred Espenak  and meteorologist Jay Anderson (I bought both, springing for the color print versions, and glad I did). One gives a lot of detail and discussion of locations and the other is a detailed road atlas for the entire path of totality.

Note that in some regions (such as eastern Oregon) crushes of crowds are anticipated, whereas other areas may be less trammeled. If possible, make reservations in advance and plan to get to your chosen spot at least the night before: because of unexpected traffic, don’t count on making a one-day driving blitz trip into the path of totality. Note also that some individuals and businesses are engaging in predatory price gouging, whereas others are opening public spaces for a celebratory sharing of the heavenly spectacle with their fellow humans. Above all, drive safely.

More detailed accounts of striking phenomena seen during my own five total solar eclipses, see “Chasing the Moon’s Shadow,” Science Probe 1(2): 80–90, 121, April 1991.

The Princeton Art Museum is celebrating the eclipse with an online exhibit called “Transient Effects,” celebrating the eclipse paintings of artist Howard Russell Butler early last century. An introductory video to eclipses and Butler narrated by exhibit curator Rolf Sinclair is here. (I was a consultant, especially for historical expeditions, writing and supplying some of the images for “Expeditions that ‘Discovered’ the Sun).

For additional accounts on the adventures of 19th-century eclipse expeditions, see “TheVictorian Space Program and “Ingenuity in the Moon’s Shadow.”

Grazulis, Thomas P., Significant Tornadoes, 1880-1989. St. Johnsbury, VT: Environmental Films, 1991. Classic and fascinating two-volume reference detailing virtually every U.S. tornado F2 and greater for more than a century. Grazulis now runs The Tornado Project.

Bell, Trudy E., The Great Dayton Flood of 1913, Arcadia Publishing, 2008. Picture book of nearly 200 images of the flood in Dayton, rescue efforts, recovery, and the construction of the Miami Conservancy District dry dams for flood control, including several pictures of Cox. (Author’s shameless marketing plug: Copies are available directly from me for the cover price of $21.99 plus $4.00 shipping, complete with inscription of your choice; for details, e-mail me), or order from the publisher.