GEOMAGNETIC STORM PREDICTED: NOAA forecasters say there is a 70% chance of G1-class geomagnetic storms on June 27th when a stream of solar wind hits Earth's magnetic field. The gaseous material is flowing from a large, irregular hole in the sun's atmosphere. High latitude sky watchers should be alert for auroras, especially in the southern hemisphere where winter darkness favors visibility. Free: Aurora Alerts.
NOCTILUCENT TORNADO: In recent nights, noctilucent clouds (NLCs) have rippled across Europe from Scandinavia to the south of France. "We have been observing NLCs every night here in N. Ireland," reports Martin McKenna of Maghera in Co. Derry. "Their brightness and complexity have been getting more advanced since the solstice, with whirls and knots glowing electric blue above a yellow midnight sunset horizon." He observed this 'noctilucent tornado' on June 25th:
"It was amazing to watch," he says. "This area then morphed into an succession of dynamic shapes--a wedge, a funnel, angel wings, an electrified smoke ring, then a long rope tornado which reached towards the horizon."
What creates these forms? The answer is "gravity waves."
Gravity waves are, essentially, waves of pressure and temperature spawned by powerful storm systems. Gravity does not vary inside the waves; they get their name from the fact that gravity acts as a restoring force that tries to restore equilibrium to up-and-down moving air. Gravity waves can propagate all the way from Earth's surface up to the mesosphere, where they imprint themselves on the the forms of noctilucent clouds. When a sufficient number of gravity waves meet, they can interfere to produce all of the structures McKenna saw--plus many more.
Summer is the season for NLCs. Summertime wisps of water vapor rise to the top of Earth's atmosphere where they wrap themselves around specks of meteor smoke. Mesospheric winds gather the resulting ice crystals into noctilucent clouds
Realtime Noctilucent Cloud Photo Gallery
MYSTERIOUS TWINNED RAINBOW: Scientists have been studying rainbows for hundreds of years, since the 17th century when Isaac Newton first explained the colorful arcs. Yet after all these years, there is one rainbow scientists do not fully understand--the "twinned bow." Jan Curtis photographed this specimen on June 21st from Cheyenne, Wyoming:
"This rare 'twinned rainbow' was perhaps the brightest rainbow I've ever seen," says Curtis. "It followed on the tails of a extremely severe thunderstorm that fortunately passed just a few miles to my north."
"Several twinned bows have been imaged, mostly during heavy showers, but currently there is no agreed explanation for them," says atmospheric optics expert Les Cowley. "They might form from a mixture of water drops and ice spheres." Indeed, Curtis reports intense hail around the time of his sighting.
"A stronger possibility is that non-spherical raindrops produce one or both bows," Cowley adds. "Surface tension forces keep small raindrops fiercely spherical but as they fall large drops are flattened by air resistance or might even oscillate between flattened and elongated spheroids."
Another striking aspect of Curtis's image is the overall double structure of the rainbow--one rainbow on the inside, another on the outside. Such double rainbows are often seen and well understood. The splitting of the inner bow into twins added a dash of mystery to this otherwise common occurance.
Realtime Space Weather Photo Gallery
ONE RING TO RULE THE STRATOSPHERE: This week, the students of Earth to Sky Calculus are in New Zealand launching cosmic ray balloons over Earth's 8th continent. To pay for the helium, they launched a ring of power to the stratosphere. Here it is floating 33 km above the Sierra Nevada mountains of central California:
You can have one for $119.95. The students are selling these rings as a fundraiser for their trip. They are made of golden-colored tungsten and inscribed with the authentic Mordor script of the One Ring.
Buy one now, and we will fly it again for you over Hobbiton, located in the North Island of New Zealand where our cosmic ray balloons will be released. Just note "Please fly it again!" in the comments section at checkout.
Each golden ring comes with a greeting card showing the ring in flight and telling the story of its journey to the edge of space. Sales support the Earth to Sky Calculus cosmic ray ballooning program and hands-on STEM research.
Far Out Gifts: Earth to Sky Store
All proceeds support hands-on STEM education