The Vortex, photo by Nick Nerbonne
My corner of Northern Michigan was all abuzz last weekend due to a relatively rare meteorological phenomenon known as a “roll cloud.” Wikipedia’s entry on Arcus clouds explains:
An arcus cloud is a low, horizontal cloud formation. Roll clouds and shelf clouds are the two types of arcus clouds. A shelf cloud is usually associated with the leading edge of thunderstorm outflow; roll clouds are usually formed by outflows of cold air from sea breezes or cold fronts in the absence of thunderstorms.
…A roll cloud is a low, horizontal, tube-shaped, and relatively rare type of arcus cloud. They differ from shelf clouds by being completely detached from other cloud features. Roll clouds usually appear to be “rolling” about a horizontal axis. They are a solitary wave called a soliton, which is a wave that has a single crest and moves without changing speed or shape.
Holland’s annual Tulip Time festival returns May 7-14, 2016. They have 4.5 MILLION tulips in Holland and are reporting about 30% of tulip bloom right now – just about perfect. Stay tuned through their Tulip Tracker.
Here’s a cool video showing how they plant Windmill Island with 55,000 tulips in a matter of hours.
Music is music, ultimately. If it makes you feel good, cool.
Prince was a musician who had a huge effect on my life. I went to school near Minneapolis when he was transforming music through his own work and what he did with a host of artists. I’m very sad at his passing. Down at the bottom I have one of my favorite clips of Prince.
I’ve been lucky enough to see the northern lights dozens of times but have probably only seen purple auroras three or four times. Causes of Color explains the colors of the northern lights:
The sun radiates all visible colors, which is why sunlight appears white. The spectrum of visible light associated with the aurora is much more restricted. The aurora is caused by charged particles in the solar wind colliding with atmospheric atoms and ions. The collisions cause the electrons of the atmospheric atoms to become excited. As the electrons return to their original energy levels, these atoms emit visible light of distinct wavelengths, to create the colors of the display we see.
The color of the aurora depends on the wavelength of the light emitted. This is determined by the specific atmospheric gas and its electrical state, and the energy of the particle that hits the atmospheric gas. The atmosphere consists mainly of nitrogen and oxygen, which emit the characteristic colors of their respective line spectra. Atomic oxygen is responsible for the two main colors of green (wavelength of 557.7 nm) and red (630.0 nm). Nitrogen causes blue and deep red hues.
Most of the auroral features are greenish-yellow, but sometimes the tall rays will turn red at their tops and along their lower edges. On rare occasions, sunlight will hit the top part of the auroral rays to create a faint blue color. On very rare occasions (once every 10 years or so) the aurora can be a deep blood red color from top to bottom. Pink hues may also be seen in the lower area of the aurora. In addition to producing light, the energetic auroral collisions transmit heat. The heat is dissipated by infrared radiation, or transported away by strong winds in the upper atmosphere.
Ross took this on August 10th last summer. He says “The Northern Lights over Moskey Basin in Isle Royale National Park. This is the first time in my life I have seen a bright purple aurora develop.”
Wikipedia says that the the Lapeer County Courthouse is the oldest original courthouse structure still in use in the state of Michigan, and one of the ten oldest in the nation.
The City of Lapeer’s history page adds:
Folklore claims Lapeer was derived from the naming of the south branch of the Flint River, which flows northwestward over quite a long distance of rocky bed in Lapeer County. French and Indian traders frequently passed over this section of the county and through the river, ultimately naming our city for the stone that lay at the river bottom. The translation of stone in French is “LePierre”; the English translation of Canadian French accent of this word is “Lapeer”. The river was named Flint, synonymous with stone.
Lapeer County was once part of the Northwest Territory. By an ordinance of the Congress of the United States passed July 13th, 1787, the whole of the territory of the United States lying northwest of the Ohio River, though still occupied by the British, was organized as the Northwest Territory. In January of 1820 the County of Oakland was formed. Governor Lewis Cass set Lapeer County’s boundaries on September 18th, 1822, although it remained part of Oakland County until it was organized. Lapeer County officially became a county on February 2nd, 1835.
I simply love Atmospheric Optics for nearly everything about lights in the sky. Regarding secondary rainbows or “double rainbows” they say that the secondary is nearly always fainter than the primary, with colors reversed and more widely separated:
Light can be reflected more than once inside a raindrop. Rays escaping after two reflections make a secondary bow.
The secondary has a radius of 51º and lies some 9º outside the primary bow. It is broader, 1.8X the width of the primary, and its colours are reversed so that the reds of the two bows always face one another. The secondary has 43% of the total brightness of the primary but its surface brightness is lower than that because its light is spread over its greater angular extent. The primary and secondary are are concentric, sharing the antisolar point for a center.
About this particular rainbow from April 2, 2016, Gerry writes: “Double rainbow from the other night after the storms. The weather in Michigan can change quickly, from rainbows to snow. Yep, that’s Michigan.”
More rainbows on Michigan in Pictures.
EarthSky says that later this month we’ll see a pair of comets, including the closet comet approach in two-and-a-half centuries:
A pair of comets showing very similar orbits are approaching Earth, and astronomers will use radio-telescopes to obtain radar images, while advanced amateurs may capture images of each of the twin comets. While both will pass at a safe distance, one of them will have a record-breakingly close flyby. Comet s was already known to be passing by Earth on March 21, 2016 at a distance of 3,290,000 miles (5.3 million km). This is about 14 times the Earth-Moon distance, and, taken by itself, sets no record.
Comet P/2016 BA14 (Pan-STARRS) will safely pass Earth on March 22,2016, passing even closer than comet 252P. Comet P/2016 BA14 flyby will be at just 2,199,933 miles (3.5 million km) or about 9 lunar distances, which is very close for a comet. In fact, this comet – P/2016 BA14 – will set a record as the third-closest known comet to pass our planet in recorded history.
…First place goes to Comet D/1770 L1 (Lexell). Comet Lexell went at just 5.9 lunar distances on July, 1770. That was about 1,410,100 miles (2.3 million km), so close that Charles Messier noted the comet’s coma looked about the size of four times the apparent size of a full moon.
Read on for lots more and do yourself a favor and subscribe to their email newsletter!
Ken took these stitched photos of Comet Pan-STAARS along with two Iridium satellite flares back in April of 2013. View his photo bigger, see more in his Skies Above slideshow and definitely follow him at Ken Scott Photography on Facebook for photos as these comets make their passes.