October 3, 2015
As we wait for the fall color season in Michigan to kick off, here’s a look back to last October and my annual rework of one of the most popular posts on Michigan in Pictures, the Science of Fall Color. If you already know the words you can sing along – have a great weekend folks!
Many think that cool weather or frost cause the leaves to change color. While temperature may dictate the color and its intensity, it is only one of many environmental factors that play a part in painting deciduous woodlands in glorious fall colors.
…The process that starts the cascade of events that result in fall color is actually a growth process. In late summer or early autumn, the days begin to get shorter, and nights are longer. Like most plants, deciduous trees and shrubs are rather sensitive to length of the dark period each day. When nights reach a threshold value and are long enough, the cells near the juncture of the leaf and the stem divide rapidly, but they do not expand. This abscission layer is a corky layer of cells that slowly begins to block transport of materials such as carbohydrates from the leaf to the branch. It also blocks the flow of minerals from the roots into the leaves. Because the starting time of the whole process is dependent on night length, fall colors appear at about the same time each year in a given location, whether temperatures are cooler or warmer than normal.
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.
Temperature, sunlight, and soil moisture greatly influence the quality of the fall foliage display. Abundant sunlight and low temperatures after the time the abscission layer forms cause the chlorophyll to be destroyed more rapidly. Cool temperatures, particularly at night, combined with abundant sunlight, promote the formation of more anthocyanins. Freezing conditions destroy the machinery responsible for manufacturing anthocyanins, so early frost means an early end to colorful foliage. Drought stress during the growing season can sometimes trigger the early formation of the abscission layer, and leaves may drop before they have a chance to develop fall coloration. A growing season with ample moisture that is followed by a rather dry, cool, sunny autumn that is marked by warm days and cool but frostless nights provides the best weather conditions for development of the brightest fall colors. Lack of wind and rain in the autumn prolongs the display; wind or heavy rain may cause the leaves to be lost before they develop their full color potential.
OK, sorry to share a novel with you. Might have to change the name of the blog to “Michigan in a Whole Bunch of Words with a Picture.”
PS: I have to think that it doesn’t look the same there this year due to the crazy storm they are still recovering from.
Tons more fall photos on Michigan in Pictures.
September 26, 2015
NASA Science reminds us that this Sunday night (Sep 27) and into the early hours of Monday, the full Harvest Moon will glide through the shadow of Earth, turning the Harvest Moon a golden-red color akin to autumn leaves:
The action begins at 9:07 PM Eastern Time on the evening of Sept 27th when the edge of the Moon first enters the amber core of Earth’s shadow. For the next three hours and 18 minutes, Earth’s shadow will move across the lunar disk.
Totality begins at 10:11 PM Eastern Time. That’s when the Moon is completely enveloped by the shadow of our planet. Totality lasts for an hour and 12 minutes so there is plenty of time to soak up the suddenly-red moonlight.
The reason the Moon turns red may be found on the surface of the Moon itself. Using your imagination, fly to the Moon and stand inside a dusty lunar crater. Look up. Overhead hangs Earth, nightside facing you, completely hiding the sun behind it. The eclipse is underway.
You might suppose that the Earth overhead would be completely dark. After all, you’re looking at the nightside of our planet. Instead, something amazing happens. When the sun is located directly behind Earth, the rim of the planet seems to catch fire! The darkened terrestrial disk is ringed by every sunrise and every sunset in the world, all at once. This light filters into the heart of Earth’s shadow, suffusing it with a coppery glow.
Click through for more including a video Science Cast of how it all works.
Kevin is the go-to moon-and-astronomy guy on Michigan in Pictures, delivering great photos and info. He shares this about the Harvest Moon:
The “Harvest Moon” is the name traditionally given to the full moon that occurs closest to the autumnal (fall) equinox. The Harvest Moon usually comes in September, but (on average) once or twice a decade it will fall in early October. At the peak of the harvest, farmers can work into the night by the light of this moon.
At this time of the year also occurs the “Harvest Moon Effect”. Usually the moon rises an average of 50 minutes later each night, but for the few nights around the Harvest Moon, the moon seems to rise at nearly the same time each night: just 25 to 30 minutes later across the U.S., and only 10 to 20 minutes later for much of Canada and Europe. Corn, pumpkins, squash, beans and wild rice are now ready for gathering.
August 31, 2015
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.
August 19, 2015
The National Park Service has opened a formal public comment period that will close on August 29, 2015 regarding future management options for wolves in Isle Royale National Park. The wolf population has plummeted because of a lack of gene flow from the mainland and park management is considering an array of options. If you have commented before, do it again as anything preceding the current comment period is now considered informal input and won’t be considered further.
Moose have important effects on island vegetation, including forest cover, and wolves are the only moose predator on the island. The wolf population on Isle Royale is very low. With their long-term survival on the island in question, the moose population is likely to increase in the short term (5-10 years), which could result in impacts to vegetation and forest cover because of over-browsing.The six plan options they lay out in this PDF are:
- No-action alternative: Current management would continue; the park would not actively manage vegetation or the moose and wolf populations
- Introduce wolves once: Reestablish wolves on the island by bringing in new wolves one time to mimic a migration event; no moose management
- Maintain both species: Maintain populations of moose and wolves on the island, which could include wolf reintroduction or augmentation
- Introduce wolves once and reduce the moose population: Reestablish wolves on the island by bringing in new wolves one time; reduce moose density if/when the wolf population is no longer impacting the moose population and moose herbivory is having a demonstrated impact on park resources
- Reduce moose population: No wolf reintroduction or augmentation; reduce moose density if/when the wolf population is no longer impacting the moose population and moose herbivory is having a demonstrated impact on park resources
- Intensively manage the moose population: No wolf reintroduction or augmentation; intensively manage moose population to a low level; potential for direct vegetation restoration through seed gathering and planting on offshore islands
Click over for more and to comment.
The Wolf Moose Project on Isle Royale is the longest continuous study of any predator-prey system in the world. Rolf Peterson began leading the wolf moose project in the early 1970s, and remains a world authority on wolves and moose. About this photo he says:
It was a remote camera photo that I set up. It shows the alpha male in the Chippewa Harbor Pack in 2009, revisiting the remains of a moose the pack killed in the adjacent pond the previous autumn. The wolves managed to yank the remains out of the pond the next summer and consume the rotting carcass.
You can view this photo background bigtacular and follow the Wolves & Moose of Isle Royale on Facebook for updates.
More wolves on Michigan in Pictures.
August 10, 2015
The annual Perseid Meteor Shower peaks August 11-13 and is the closest thing to a sure thing in when you’re talking meteor showers. The Perseids kick out 10+ meteors per hour at peak, and the darker your setting, the more you will see. EarthSky has detailed tips & diagrams about this summer favorite in Everything you need to know: Perseid meteor shower:
Start watching in the second week of August, when the Delta Aquarid meteor shower is rambling along steadily, reliably producing meteors each night. Then keep watching in the second week of August, when the Perseids are rising to a peak. The Perseid shower is known to rise gradually to a peak, then fall off rapidly afterwards. In early August (and even through the peak nights), you’ll see them combine with meteors from the Delta Aquarid shower. Overall, the meteors will be increasing in number from early August onward, and better yet, the moonlight will diminish until the new moon on August 14, 2015.
Don’t rule out early evenings. As a general rule, the Perseid meteors tend to be few and far between at nightfall and early evening. Yet, if fortune smiles upon you, you could catch an earthgrazer – a looooong, slow, colorful meteor traveling horizontally across the evening sky. Earthgrazer meteors are rare but most exciting and memorable, if you happen to spot one. Perseid earthgrazers can only appear at early to mid-evening, when the radiant point of the shower is close to the horizon.
As evening deepens into late night, and the meteor shower radiant climbs higher in the sky, more and more Perseid meteors streak the nighttime. The meteors don’t really start to pick up steam until after midnight, and usually don’t bombard the sky most abundantly until the wee hours before dawn. You may see 50 or so meteors per hour in a dark sky.
An open sky is essential because these meteors fly across the sky in many different directions and in front of numerous constellations. If you trace the paths of the Perseid meteors backward, you’d find they come from a point in front of the constellation Perseus. But once again, you don’t need to know Perseus or any other constellation to watch this or any meteor shower.
Read on at EarthSky for lots more and I hope you get a chance to enjoy Michigan after dark this week – it’s worth it!!
View Ken’s August 2012 composite of 8 meteors taken over an hour at the Grand Traverse Lighthouse on Cathead Bay bigger, see more in his massive Skies Above slideshow and head over to Ken Scott Photography on Facebook for a Perseids photo from last night!
PS: You can see a timelapse clip from this night on YouTube too!
July 15, 2015
Anyone remember Hipstamatic? This is a shot of Pluto in Dave Kirby’s cool installation of the planets along the TART trail in Traverse City (created prior to the de-planetization of Pluto). I don’t usually feature my own photos here, but I had to find something to celebrate NASA’s historic 3,000,000,000 mile journey to Pluto:
After a decade-long journey through our solar system, New Horizons made its closest approach to Pluto Tuesday, about 7,750 miles above the surface — roughly the same distance from New York to Mumbai, India – making it the first-ever space mission to explore a world so far from Earth.
“I’m delighted at this latest accomplishment by NASA, another first that demonstrates once again how the United States leads the world in space,” said John Holdren, assistant to the President for Science and Technology and director of the White House Office of Science and Technology Policy. “New Horizons is the latest in a long line of scientific accomplishments at NASA, including multiple missions orbiting and exploring the surface of Mars in advance of human visits still to come; the remarkable Kepler mission to identify Earth-like planets around stars other than our own; and the DSCOVR satellite that soon will be beaming back images of the whole Earth in near real-time from a vantage point a million miles away. As New Horizons completes its flyby of Pluto and continues deeper into the Kuiper Belt, NASA’s multifaceted journey of discovery continues.”
More science on Michigan in Pictures.