A Rainbow Primer


Incomplete, photo by Jamie MacDonald

I’ve never found a better website for information about rainbows and other optical phenomena than Atmospheric Optics. They have information about all flavors of rainbows including the primary rainbow, and explain that rainbows are disks of light rather than sets of coloured rings:

Early morning and late afternoon are the best times to see them because the sun must not be too high. Rainbows are always opposite the sun and their centres are below the horizon at the the antisolar point. The lower the sun the higher is the bow.

Red is always outermost in the primary bow with orange, yellow, green and blue within. Occasionally, when the raindrops are small, fainter supernumerary arcs of electric greens, pinks and purples lie just inside the main bow.

A rainbow is not just a set of coloured rings. The sky inside is bright because raindrops direct light there too. The primary bow is a shining disk brightening very strongly towards its rim.

About this particular rainbow, Jamie writes:

This is the first time I have ever seen part of a rainbow in open skies. Look to the sky above the barn and you can just make out the missing portion of the rainbow.

View his photo bigger and see more in his Landscapes slideshow.

More rainbows on Michigan in Pictures!

#TBT: Comet Biela and the Great Michigan Fire of 1871

House fire

House fire, photo by Ogedn

“The proponents of the cometary explanation cite many fascinating details confirmed by eye witness reports: the descent of fire from the heavens, a great ‘tornado’ of fire rushing across the landscape and tearing buildings from their foundations, descending balls of fire, a rain of red dust, great explosions of wind accompanied by blasts of thunder, buildings exploding into flame where no fire was burning, and a good deal more.”

We all probably know of Mrs. O’Leary’s cow and the Chicago Fire that burned over three miles of the city to the ground, but perhaps you’d care to take “Fires beginning October 8, 1871” for $500? Four fires began 144 years ago on this day in 1871: the Great Chicago Fire, the Great Michigan Fire, the Peshtigo (Wisconsin) Fire and the Port Huron Fire.

I’m going to let the crew of thunderbolts take it away with an excerpt from their fascinating feature The Comet and the Chicago Fire:

Contrary to popular folklore, the Chicago fire is not the worst in U.S. history. It was not even the worst to occur on October 8 that year. The same evening—in fact, at the same time, about 9:30—a fierce wildfire struck in Peshtigo, Wisconsin, over 200 miles to the north of Chicago, destroying the town and a dozen other villages. Estimates of those killed range upward from 1200 to 2500 in a single night. It was not the Chicago fire but the simultaneous “Peshtigo Fire” that was the deadliest in U.S. history.

And there is more. On the same evening, across Lake Michigan, another fire also wreaked havoc. Though smaller fires had been burning for some time—not unusual under the reported conditions—the most intense outburst appears to have erupted simultaneously with the Chicago and Peshtigo fires. The blaze is said to have then burned for over a month, consuming over 2,000,000 acres and killing at least 200.

Concerning the Michigan outburst, it is reported that numerous fires endangered towns across the state. The city of Holland was destroyed by fire and in Lansing flames threatened the agricultural college. In Thumb, farmers fled an inferno that some newspapers dubbed, “The Fiery Fiend.” Reports say that fires threatened Muskegon, South Haven, Grand Rapids, Wayland, reaching the outskirts of Big Rapids. A steamship passing the Manitou Islands reported they were on fire.

There can be no doubt that weather conditions at the time favored wildfires. But never before, and never since, has the U.S. seen such wildly destructive simultaneous conflagrations. This “coincidence”, combined with many unusual phenomena reported by eyewitnesses, has led some to conclude that an extraordinary force, one not of the earth, was a more likely “arson” than either a misbehaving cow or a regional drought.

In 1883, Ignatius Donnelly, author of Ragnarok: the Rain of Fire and Gravel, suggested that in early historic times our Earth suffered great catastrophes from cometary intruders. To this claim he added: “There is reason to believe that the present generation has passed through the gaseous prolongation of a comet’s tail, and that hundreds of human beings lost their lives”. He was referring to the conflagration of 1871.

Definitely read on for much more about the possibility of a comet’s tail, perhaps Comet Biela, fueling the fires.

Ogedn took this photo of a controlled burn by the local fire department, who practiced on this house before letting it burn. View the photo background big and see this and lots more in their slideshow.

Tons more Michigan history on Michigan in Pictures.

PS: I definitely did more research on this than I should have on this, and while the cometary theory and Comet Biela was observed to be broken apart on its pass in 1846, it may be that Biela’s Comet returned in September of 1872. In any case check the article out and also their Picture of the Day for a lot more than you’ve probably thought about.

The Science of Sand Waves, Silver Lake Dunes Edition

Sand Waves

Sand Waves, photo by Charles Bonham

Confession: I probably don’t give Silver Lake Dunes State Park enough love. What an incredible place.

In Scientific American Robert S. Anderson, associate professor of earth sciences at the University of California at Santa Cruz explains why regular, wavelike shapes form when the wind blows over the sand on the beach for a long time:

Ripples in sand, found on both beaches and dunes, are one of nature’s most ubiquitous and spectacular examples of self-organization. They do not result from some predetermined pattern in the wind that is somehow impressed on the surface, but rather from the dynamics of individual grains in motion across the surface. They arise whenever wind blows strongly enough over a sand surface to entrain grains into the wind. The subsequent hopping and leaping of these grains is called saltation. Saltating grains travel elongated, asymmetric trajectories: Rising relatively steeply off the bed, their path is then stretched downwind as they are accelerated by drag forces. They impact the sand surface centimeters to tens of centimeters downwind, typically at a low angle, around 10 degrees. It is this beam of wind-accelerated grains impacting the sand surface at a low angle that is responsible for ripples.

“An artificially flattened sand surface will not remain flat for long. (Try it on the beach or on the upwind side of a dune and see for yourself.) Small irregular mottles in the sand surface, perhaps a couple centimeters in wavelength, rapidly arise and grow once the wind starts to blow hard enough to initiate saltation. They then slowly organize themselves into more regular waves whose low crests are aligned perpendicular to the wind direction and begin to march slowly downwind. Typical ripple spacing is about 10 centimeters, whereas the typical height of the crests above the troughs is a few millimeters. The pattern is never perfect, but instead the ripple crests occasionally split or terminate, generating a pattern that looks remarkably like one’s fingerprint.

Read on for a whole lot more including Michigan Sea Grant educator Walt Hoagman explaining how the speed of wind (and water) over sand influences the waves.

View Charles’s photo background bigilicious and definitely check out his incredible Silver Lake Dunes photos.

More science, more dunes and more summer wallpaper on Michigan in Pictures.

Milky Way, Otter Creek & Sally Ride

Milky Otter

Milky Otter, photo by Heather Higham

The stars don’t look bigger, but they do look brighter.
~Sally Ride

Google reminded me this morning that today would have been astronaut & physicist Sally Ride’s 64th birthday. The Wikipedia entry for Sally Ride says that on June 18, 1983, she became the first American woman in space. Along with her NASA career, Ride also wrote a number of books aimed at encouraging children to study science, something I strongly believe that all of us should remember to do with the young girls & boys who look up to us.

To put a Michigan bow on this, be sure to check out the Women in Aviation and Space exhibit at the AirZoo in Portage. The exhibit honors women including astronaut Sally Ride and aviation pioneer Amelia Earhart. It includes original uniforms, a visual history mural, photo collages, a timeline and a unique mosaic, which includes each of the 1,102 WASP plus Jacqueline Cochran, founder of the Women in Aviation and Space organization.

Heather took this incredible shot at Otter Creek in the Sleeping Bear Dunes National Lakeshore. View her photo bigger and see more in her Night Sky slideshow.

PS: If you want to get your Night Sky fix at the Sleeping Bear Dunes National Lakeshore, check out their Your Park After Dark program this summer!

North Bar Lake

North Bar Lake by Sarah Hunt

North Bar Lake, photo by Sarah Hunt

Who’s ready for a break from snow & ice? The Sleeping Bear Dunes National Lakeshore page on the North Bar Lake Overlook says (in part):

The name describes how the lake formed: it is ponded behind a sand bar. At times, the sand bar builds up and separates North Bar Lake from Lake Michigan. At other times, a small connecting channel exists between the two lakes. North Bar Lake occupies part of a former bay on Lake Michigan. This ancient bay was flanked by headlands on both sides: Empire Bluffs on the south and Sleeping Bear Bluffs on the north. Shorelines have a natural tendency to become straighter with time. Wave action focuses on the headlands and wears them back, while shoreline currents carry sediment to the quiet bays and fill them in. Deeper parts of the bay are often left as lakes when sand fills in the shallower parts.

The same process that formed North Bar Lake also formed many of the other lakes in northern Michigan: Glen, Crystal, Elk and Torch Lakes, for example.

Here’s more about the geology of the Sleeping Bear and more about North Bar Lake, to which I’d add that the lake is a great place for skim boards because the channel between North Bar & Lake Michigan is only a few inches deep!

Sarah took this photo last summer. Click it to view background bigalicious and check out lots more of her incredible and adventurous photography at instagram.com/oni_one_.

PS: If you’re still not full-up on winter and ice, might I suggest this pic she took in this area of Sleeping Bear last week!

Foggy Morning on Portage Lake and the Tyndall Effect

Foggy morning, photo by Jiqing Fan

Wikipedia says that Portage Lake is part of the Keweenaw Waterway, a partly natural, partly artificial waterway that cuts across the Keweenaw Peninsula to provide access for shipping from Lake Superior. If you click the link you can get an aerial view.

View Jiqing Fan’s photo bigger and see more in his massive Houghton & UP MI slideshow. He writes:

Saw the fog on Lake Portage from my apartment window after I woke up today. I knew the potential this fog can bring so I darted down to the lake shore. But the fog was so heavy that the foliage on the other bank were completely blocked. Just when I was about to give up and head back for school, the fog started to break as the sun rises. And then the magic started to unfold before my eyes. Soon the fog lifted and fill the campus uphill, the entire campus was bathed in soft morning light and there were Tyndall effect everywhere! I can not think of a better way to start a day of work.

What’s the Tyndall effect you ask? The UC Davis ChemWiki explains that the Tyndall effect was identified by 19th Century Irish scientist John Tyndall.

Because a colloidal solution or substance (like fog) is made up of scattered particles (like dust and water in air), light cannot travel straight through. Rather, it collides with these micro-particles and scatters causing the effect of a visible light beam. This effect was observed and described by John Tyndall as the Tyndall Effect.

The Tyndall effect is an easy way of determining whether a mixture is colloidal or not. When light is shined through a true solution, the light passes cleanly through the solution, however when light is passed through a colloidal solution, the substance in the dispersed phases scatters the light in all directions, making it readily seen.

For example, light is not reflected when passing through water because it is not a colloid. It is however reflected in all directions when it passes through milk, which is colloidal. A second example is shining a flashlight into fog or smog; the beam of light can be easily seen because the fog is a colloid.

Yay science!

The Beauty of My Nemesis: Snowflake Edition

The Beauty of My Nemesis

The Beauty of My Nemesis, photo by pkHyperFocal

Waaaay back when I started out on the capital “I” Internet with an online publication called the Northern Michigan Journal. For over five years I edited NMJ, producing around 4 issues a year that featured some interesting work from a wide range of writers & artists.

Two of these were my friends Jerry Dennis and Glenn Wolff, a writer/artist duo who collaborated on several books.  Their first was called It’s Raining Frogs & Fishes: Four Seasons of Natural Phenomena and Oddities of the Sky, a fascinating romp through the oddities and beauties of the natural world through Jerry’s captivating prose and Glenn’s engaging drawings. You can click that link to learn more about the book from Jerry’s website. Trust me, it’s the perfect gift for the nature lover or scientist in your life!

Glenn & Jerry shared a chapter from the book with me that I published to the inaugural issue of NMJ. Here’s the beginning of Nature Baroque: Snowflakes & Crystals:

There is more to the birth of a snowflake than Aristotle’s assertion that “when a cloud freezes there is snow.” Snow is not merely frozen rain. Rain occasionally freezes, falling to the ground as sleet or freezing rain, but snow originates independent of atmospheric drops of water. Individual ice crystals for high in the atmosphere when water vapor freezes around dust or other particulates. Without particles to serve as condensation nuclei, water vapor can be cooled to -40 degrees Fahrenheit before freezing occurs. A supercooled cloud of this sort seeded with a few particles often escalates into a snowstorm. The individual crystals collect additional molecules of water vapor one at a time, building on one another symmetrically in a rapidly growing, widening circle. Temperature, wind, humidity, and even barometric pressure will determine the growth and ultimate form of the crystal. Large and elaborate crystals for at higher temperatures and humidity while, while the small, basic crystals such as those common in polar regions form when temperature and humidity are very low. As the crystals fall they bump against each other, breaking off pieces of ice that in turn serve as nuclei for new crystals. As they pass through warmer layers of air they adhere to one another, congregating into snowflakes that may contain a thousand or more crystals.

Snowflakes, then, are aggregates of snow crystals. When the temperature is near or slightly above freezing, snowflakes become wet, adhere to other flakes, and grow to two or three inches in diameter. On very rare occasions, they can grow larger yet. According to a report in a 1915 issue of Monthly Weather Review, a snowfall on January 28, 1887 dropped flakes “larger than milk pans,” measuring fifteen inches in diameter by eight inches thick across several square miles near Fort Keogh, Montana.

Only when the temperature remains consistently below freezing will complete, individual crystals fall to the ground. If the temperature of the cloud they form in and the air they descend through is warmer than 27 degrees Fahrenheit, the crystals tend to be flat and hexagonal. Between 27 and 23 degrees, they tend to be needle-shaped. Between 23 and 18 they are likely to be hollow and columnar, with prismatic sides. At temperatures below 18 they can be columnar, hexagonal, or fernlike. Virtually all have six sides. That hexagonal tendency is something of a mystery, although some scientists suggest it is produced by electrical charges in the crystals, while others say it is basic to the molecular structure of water molecules. The atoms in a molecule of H20 are arranged, in physicist Hans C. von Baeyer’s graphic description, “with two little hydrogens stuck onto a big oxygen like ears on a Mickey Mouse’s head.” Scientists like von Baeyer believe that the angle at which the hydrogen molecules protrude from the oxygen atom–about 120 degrees–causes snow crystals to grow to a six-pointed symmetry that repeats the molecular structure of water.

Read on for much more including whether or not two snow crystals are alike, heavy snowfalls and snow words & myths.

View this photo background bigtacular and see more in pk’s really, really cool Chromatic Progression slideshow.

More snow, sciencewinter wallpaper on Michigan in Pictures!

Ball Ice and the Ice Boulders on Lake Michigan

Ice Boulders by Leda Olmstead
Lake Michigan Ice Boulders, photo by Leda Olmsted

Todays post is from the “Ain’t it Cool” Department. A couple of weeks ago Leelanau County resident Leda Olmsted was walking the Lake Michigan shore in the Sleeping Bear Dunes National Lakeshore when she came across this incredible scene. TV 7&4 reports in Ice boulders roll onto shores of Lake Michigan that Leda took some photos, uploaded to the news station’s Facebook and:

Leda says she was shocked by the response. Olmsted explains, “From there it got like 800 shares and thousands of likes and overnight I had Good Morning America and The Weather Channel calling me, so it has been a really crazy weekend!”

Deputy Superintendent from the Sleeping Bear Dunes National Lakeshore Tom Ulrich says, “It’s not that it never happens and this is a once in a decade thing, it happens more often than that, but these are very large and got bigger than they normally get.”

The ice balls or boulders along the shores of Lake Michigan are about the size of giant beach balls or basketballs and weigh up to 50 pounds.

Click to watch the video from UpNorthLive with Leda.

I looked a little further into the phenomenon and found and AIR PHOTO INTERPRETATION OF GREAT LAKES ICE FEATURES by Ernest W. Marshall  in the Great Lakes Digital Library at the University of Michigan. With the help of Marshall’s information, here’s an explanation of how ball ice forms:

Ball ice consists of roughly spherical masses of slush and frazil ice that accrete in turbulent water. Frazil ice (via Wikipedia)is a collection of loose, randomly oriented needle-shaped ice crystals that form in open, turbulent, supercooled water. Lumps that form in the less turbulent zones are typically flattened discs, while those formed in the extremely turbulent zone near the shoreline ice where wave action is strongest form into spheres.

The author explains that ball ice is a feature common to all of the Great Lakes and can occur at any time during the winter where water turbulence breaks up a slush layer. You can read more about this in Great Lakes Ice Features.

More science, winter and amazing on Michigan in Pictures!

Ice Machine: How Shoreline Ice Forms on the Great Lakes

Lake Michigan Ice by Tim Wenzel

Snowball Fight Anyone?, photo by Timothy Wenzel

One of my favorite photo blogs is the Earth Science Picture of the Day from NASA. In Wednesday’s blog, Timothy wrote:

This photo, taken on January 24, 2013, illustrates how ice on Lake Michigan’s eastern shore can achieve heights of many feet; by accretion of floating snowball-size ice balls thrown upward by wave action. The maximum wave height (crest to trough) on Lake Michigan on this day was approximately 6 ft (2 m). What results is a landscape that looks almost volcanicClick here to see video of this phenomenon. Note that the lake itself is a slurry of ice and water.

Definitely check Tim’s video out! See the photo background bigtacular and see more in Timothy’s work including more photos from the day in his Weather Underground gallery.

More EPOD awesomeness on Michigan in Pictures!

Judas Carp

Club Carp by docksidepress

Club Carp, photo by docksidepress

Judas test: Will carp betray their own? on the Great Lakes Echo says that University of Minnesota researchers are working to put a new tool in the arsenal of those seeking to thwart the voracious and invasive Asian carp.

The researchers are fitting common carp, or “Judas fish,” with transmitters to lead them to other, larger schools of common carp, the station reports.

“(Carp) seem to be actually exceptionally social, they really hang out together,” researcher Peter Sorensen told the station. “We have to confirm that, but it sure looks that way.”

Watch the report from CBS Minnesota to learn how researchers hope to use the same technique to locate Asian carp populations for extermination.

Check out Matt’s photo on black and see more from Matt on Michigan in Pictures.

More fish on Michigan in Pictures.