September 25, 2014
Three years ago I posted this. It’s such good and useful information that I thought I’d share it again! #TBT?
The Science of Color in Autumn Leaves from the United States National Arboretum explains that process that starts the cascade of events that result in fall color is a growth process that starts in late summer or early autumn. When the nights get long enough, a layer of cells called the abscission layer forms that begins to block transport of materials from the leaf to the branch.
During the growing season, chlorophyll is replaced constantly in the leaves. Chlorophyll breaks down with exposure to light in the same way that colored paper fades in sunlight. The leaves must manufacture new chlorophyll to replace chlorophyll that is lost in this way. In autumn, when the connection between the leaf and the rest of the plant begins to be blocked off, the production of chlorophyll slows and then stops. In a relatively short time period, the chlorophyll disappears completely.
This is when autumn colors are revealed. Chlorophyll normally masks the yellow pigments known as xanthophylls and the orange pigments called carotenoids — both then become visible when the green chlorophyll is gone. These colors are present in the leaf throughout the growing season. Red and purple pigments come from anthocyanins. In the fall anthocyanins are manufactured from the sugars that are trapped in the leaf. In most plants anthocyanins are typically not present during the growing season.
As autumn progresses, the cells in the abscission layer become more dry and corky. The connections between cells become weakened, and the leaves break off with time. Many trees and shrubs lose their leaves when they are still very colorful. Some plants retain a great deal of their foliage through much of the winter, but the leaves do not retain their color for long. Like chlorophyll, the other pigments eventually break down in light or when they are frozen. The only pigments that remain are tannins, which are brown.
The explain that because the starting time of the whole process is dependent on night length, fall colors appear at more or less the same time every year and are not overly dependent on temperature, rainfall or other factors, other than the fact that weather can shorten or prolong the show by stripping leaves from trees.
Lots more fall color on Michigan in Pictures!
April 11, 2014
In “A sad day” for Michigan bats: White-nose syndrome found in 3 counties, Michigan Radio reports:
The Michigan Department of Natural Resources today confirmed the presence of white-nose syndrome in three counties: Alpena, Dickinson and Mackinac.
White-nose syndrome is blamed for the deaths of six million bats in 27 states and five Canadian provinces since 2006. In some places where the fungus outbreak has taken hold, 90% of the bats have died.
“We anticipated that this day would come. It’s not unexpected. But it’s still a sad day,” says Dan O’Brien, a state wildlife veterinarian. “Once this fungus gets into a bat hibernacula it’s going to be there, current evidence suggests, for a long time.”
The fungal disease could have a big impact on Michigan’s economy. Wildlife biologists estimate bats have a roughly $1 billion impact on the state’s agriculture industry by eating harmful insects.
“At this point, there is no effective treatment for WNS and no practical way to deliver the treatment to millions of affected bats even if treatment existed. Rehabilitation of bats is prohibited in Michigan because of the potential for the exposure of humans to rabies,” said O’Brien. “The best thing the public can do when they find a dying or dead bat is to leave it alone and keep children, livestock and pets away from it.”
Bat die-offs can be reported through an observation report on the DNR website at www.michigan.gov/wildlife or by calling the DNR at 517-336-3050.
More animals on Michigan in Pictures.
April 5, 2014
For as long as we know, celestial signs have been read to signify calamity and change, and apparently the total lunar eclipse in the early morning hours of April 15, 2014 that kicks off a two-year tetrad of lunar eclipses is no exception.
We’ve been receiving a number of inquiries about Blood Moons in 2014 and 2015. The Blood Moons most people are asking about are not part of astronomy. Their origin is religious, at least according to Christian pastor John Hagee, who wrote a 2013 book about Blood Moons. However, both astronomers and some proponents of Christian prophesy are talking about the upcoming lunar tetrad – a series of total lunar eclipses – which begins on the night of April 14-15, 2014. We at EarthSky don’t have any special knowledge about the purported Blood Moons of Biblical prophesy. But, since they’re moons, and since people are asking us, we wanted to reply.
The full moon nearly always appears coppery red during a total lunar eclipse. That’s because the dispersed light from all the Earth’s sunrises and sunsets falls on the face of the moon at mid-eclipse. Thus the term blood moon can be and probably is applied to any and all total lunar eclipses…
Both astronomers and followers of certain Christian pastors are talking about the lunar tetrad of 2014-2015. What is a tetrad? It’s four successive total lunar eclipses, with no partial lunar eclipses in between, each of which is separated from the other by six lunar months (six full moons)
We’re not experts on prophecy of any kind. But we’ll tell you what we know about the new definition for Blood Moon that has raised so many questions recently.
From what we’ve been able to gather, two Christian pastors, Mark Blitz and John Hagee, use the term Blood Moon to apply to the full moons of the upcoming tetrad – four successive total lunar eclipses, with no partial lunar eclipses in between, each of which is separated from the other by six lunar months (six full moons) – in 2014 and 2015. John Hagee appears to have popularized the term in his 2013 book Four Blood Moons: Something is About to Change.
As if we didn’t have enough to look forward to on April 15th! Read on for lots more. The four eclipses are this one, October 8 2014 and April 4 & September 28, 2015. Here’s the eclipse viewing times for Michigan – times for other time zones can be found on EarthSky.
The April 15th eclipse begins at 2 AM Eastern time when the edge of the moon first enters the amber core of Earth’s shadow. Totality occurs during a 78 minute interval beginning around 3 o’clock in the morning on the east coast, midnight on the west coast. Weather permitting, the red moon will be easy to see across the entirety of North America.
Eastern Daylight Time (April 15, 2014)
Partial umbral eclipse begins: 1:58 a.m. EDT on April 15
Total eclipse begins: 3:07 a.m. EDT
Greatest eclipse: 3:46 a.m. EDT
Total eclipse ends: 4:25 a.m. EDT
Partial eclipse ends: 5:33 a.m. EDT
Michael took this photo of the lunar eclipse on February 20, 2008. View it bigger and see more in his The Moon slideshow.
More of the moon on Michigan in Pictures!
March 12, 2014
The Earth Science class for educators at Michigan Tech has an online textbook on Michigan Geography & Geology that’s pretty cool. The chapter on the Ledges at Grand Ledge includes At the Edge of an Ancient Ocean that talks about the rocks that make up The Ledges and begins:
The rocks at Grand Ledge are significant for several reasons. Grand Ledge is an “oasis” of bedrock in an “ocean” of glacial drift that blankets the Lower Peninsula, providing geologists a window into the distant past. The diverse set of sedimentary rocks contains a wealth of information on the plants and animals that dominated the Pennsylvanian Period, about 320 to 290 million years ago. The characteristics of the rocks allowed geologists to reconstruct the changing environment that marked the demise of a great inland ocean. The rocks have been quarried and hold economic value. Lastly, Grand Ledge is scenic and enjoyed by hikers, paddlers, and climbers.
Nearly all students of Michigan geology make a pilgrimage to Grand Ledge at some point in their careers. Good exposures of sedimentary rocks are rare in the Lower Peninsula. Not only are the rocks well exposed but they offer an opportunity to test your skills in identifying a variety of sandstones, some shale and limestone, and even 2 coal. The rocks are exposed in a few abandon quarries and in exposures along the Grand River. To get a good look at the rocks you will need drive between exposure north and south of the river. But don’t be discouraged; the distances are short.
As always in geology, the best place to start is at the base of the stratigraphic section, the oldest rocks. The lower part of the section contains shale, siltstone, and type of sandstone called greywacke. The shale is gray and so fine-grained that you cannot see the mud-sized particles that compose it. If you are brave, you might put a tiny piece in your mouth and push it around a bit. Shale feels smooth, almost creamy, a result of the mud. The shale is also soft and erodes to relatively gentle slopes. Shale is exposed at the base of the layers at the Face Brick Quarry. Think of the light-colored siltstone as a silty shale. You might rub the rock against your thumb and see if any small, visible grains come loose. Again, a taste test might be in order. Siltstone will leave a 3 gritty feel in your mouth. Siltstone is exposed at the base of the rock layers at the American Vitrified Quarry. The greywacke is a greenish-gray colored sandstone and the sand grains are visible to your unaided eye, no tasting required. With a hand lens you can see the rock is made of a mixture of sand sizes, what geologists call poor sorting, and a variety of sand compositions, including quartz, feldspar, mica, and fragments of pre-existing rocks. Greywacke is exposed just above the beach at the Face Brick Quarry.
More winter wallpaper on Michigan in Pictures.
March 11, 2014
NOAA’s current space weather forecast reports an M Class (moderate) solar flare from solar region AR2002. Spaceweather.com adds that AR2002 has destabilized its magnetic field, making it more likely to erupt, and that NOAA forecasters are estimating a 60% chance of M-class flares and a 10% chance of X-class flares during the next 24 hours. X-class flares are major solar events that can spawn incredible auroras visible far to the south of us, planet-wide radio blackouts and long-lasting radiation storms. Click to Space Weather for a video of AR2002 development.
While there’s not much chance of a major event, I thought it was interesting that 25 years ago this week, one of the most significant solar storms in memory created a spectacle in the skies as it demonstrated the power and danger of solar weather to modern society. A Conflagration of Storms begins:
On Thursday, March 9, 1989 astronomers at the Kitt Peak Solar Observatory spotted a major solar flare in progress. Eight minutes later, the Earth’s outer atmosphere was struck by a wave of powerful ultraviolet and X-ray radiation. Then the next day, an even more powerful eruption launched a cloud of gas 36 times the size of the from Active Region 5395 nearly dead center on the Sun. The storm cloud rushed out from the Sun at a million miles an hour, and on the evening of Monday, March 13 it struck the Earth. Alaskan and Scandinavian observers were treated to a spectacular auroral display that night. Intense colors from the rare Great Aurora painted the skies around the world in vivid shapes that moved like legendary dragons. Ghostly celestial armies battled from sunset to midnight. Newspapers that reported this event considered the aurora, itself, to be the most newsworthy aspect of the storm. Seen as far south as Florida and Cuba, the vast majority of people in the Northern Hemisphere had never seen such a spectacle. Some even worried that a nuclear first-strike might be in progress.
…Millions marveled at the beautiful celestial spectacle, and solar physicists delighted in the new data it brought to them, but many more were not so happy about it.
Silently, the storm had impacted the magnetic field of the Earth and caused a powerful jet stream of current to flow 1000 miles above the ground. Like a drunken serpent, its coils gyrated and swooped downwards in latitude, deep into North America. As midnight came and went, invisible electromagnetic forces were staging their own pitched battle in a vast arena bounded by the sky above and the rocky subterranean reaches of the Earth. A river of charged particles and electrons in the ionosphere flowed from west to east, inducing powerful electrical currents in the ground that surged into many natural nooks and crannies. There, beneath the surface, natural rock resistance murdered them quietly in the night. Nature has its own effective defenses for these currents, but human technology was not so fortunate on this particular night. The currents eventually found harbor in the electrical systems of Great Britain, the United States and Canada.
You can read on for more about how the storm spawned a power outage in Quebec and pushed US systems to the brink of collapse. If you want to totally geek out on auroral science, check this article out about how the Earth’s magnetosphere actually extends itself to block solar storms.
February 15, 2014
You may have seen one or more of these incredible ice photos making the email round as Lake Michigan or Lake Huron ice. The Snopes.com article above says that they and many more were taken Antarctic base of Dumont D’Urville by Tony Travouillon in 2002. A shout-out to TC weatherman Joe Charlevoix who posted a story earlier in the week debunking the hoax!
While we don’t have that level of brilliant blue, our ice does get bluish. Via Shawn Malone at the Earth Science Picture of the Day, I found an informative article by Larry Gedney about blue ice & snow that says:
It is a common misconception that the blue color exhibited by glaciers, old sea ice, or even holes poked into a snow bank is due to the same phenomenon that makes the sky blue–light scattering. But nature has more than one recipe for producing the color blue. In frozen water and in the sky the processes are almost the reverse of each other.
A blue sky results when light bounces off molecules and small dust particles in the atmosphere. Because blue light scatters more than red does, the sky looks blue except in the direction of the sun (particularly when the sun is near the horizon and the blue light is scattered out of the sunlight, leaving the red color of sunrises and sunsets).
When light passes through ice, however, the red light is absorbed while the blue is transmitted. Were the operating process scattering as in the atmosphere, then the transmitted light would be red, not blue. However, because of the large size of snow grains and ice crystals, all wavelengths of visible light are scattered equally. Scattering therefore does not play an appreciable role in determining the color of the transmitted light.
It takes an appreciable thickness of pure ice to absorb enough red light so that only the blue is transmitted. You can see the effect in snow at fairly shallow depths because the light is bounced around repeatedly between ice grains, losing a little red at each bounce. You can even see a gradation of color within a hole poked in clean, deep snow. Near the opening, the transmitted light will be yellowish. As the depth increases, the corer will pass through yellowish-green, greenish-blue and finally vivid blue. If the hole is deep enough, the color and light disappear completely when all the light is absorbed.
The color of ice can be used to estimate its strength and even how long it has been frozen. Arctic Ocean ice is white during its first year because it is full of bubbles. Light will travel only a short distance before it is scattered by the bubbles and reflected back out. As a result, little absorption occurs, and the light leaves with the same color it had when it went in.
There’s more (lots more) on water, snow & ice from the University of Alaska, Fairbanks.
Heather took this photo at Point Betsie last weekend. View it bigger and see more in her Winter slideshow.
February 8, 2014
The other night I came across an incredible video tour of the International Space Station by Commander Sunita Williams of NASA before she departed for Earth. It’s one of the most amazing things I’ve ever seen and does so much to make the experience of living, working and moving in space a lot more tangible.
Commander Williams is a big part of what makes this video so engaging. She guides you through the corridors of the space station with a skill for explanation that I have seldom (if ever) seen. If she were born a hundred or so miles to the east, she’d be a Michigander. She wasn’t though, so I guess it might not be true what my grandmother told me about Ohio. Read her blog of the mission at NASA. (great photos)
Kudos to Commander Williams, and to everyone who worked across national and other divisions to make the ISS a reality. This video really made my day and I hope it makes yours – click to watch on YouTube!
About the photo, Kevin writes:
The International Space Station flies through the constellation Orion in the skies over downtown Grand Rapids, Michigan on a chilly and windy October evening.
This was a low pass in the southern sky (maximum altitude 34 degrees) so I decided to drive downtown to see if I could get a shot as the spacecraft flew over the buildings. I had done something similar in March of 2010, and figured if I could do it once, a second time wouldn’t be a problem.
Using timings and coordinates from Heavens Above via their Android app, I was able to determine where the flyover would begin and end. I set up my camera and did a few test shots before the actual time, and was ready by the time ISS was visible over the south-southwestern horizon.
I timed it so the light from the station would already be in the FOV of the lens, and opened the shutter until it disappeared a short time later. Then it was home to the computer to see if I could make anything out of the image. I guess I did.
Who says you can’t do astrophotography from the city? :)
More nighttime photos on Michigan in Pictures.