Q. Why does a spectacular sunset so often follow a late-afternoon thunderstorm?
A. Some of the important factors in a photo-worthy red-orange sunset after a storm include timing, cloud patterns, the scattering of sunlight, and air quality in the lower atmosphere, according to the Storm Prediction Center of the National Weather Service and the National Oceanic and Atmospheric Administration.
Most thunderstorms occur in the late afternoon or the evening, close to sunset, when radiant heating and atmospheric instability have reached their peaks. In the aftermath of such a storm, midlevel and high clouds may be left behind, especially cirrus and altocumulus clouds that are ideal as a canvas for painting by the sun’s last rays.
Sign Up for the Science Times Newsletter
Every week, we'll bring you stories that capture the wonders of the human body, nature and the cosmos.
Water-filled clouds in the lower atmosphere will have been depleted by the storm.
Those last rays are mostly red or orange because the longer path that light takes through the atmosphere as the sun’s angle becomes ever lower means that the wavelengths of other colors have been scattered away.
Contrary to popular belief, clean air scrubbed by a storm lets more red rays reach the viewer than dirty air would.
Dust and smog at low levels would scatter the light too much for an ideal sunset. (High-level particles like those left by a volcanic eruption, can, however, cause a red afterglow.) question@nytimes.com.
A great “might have been” for the universe, or at least for the people who study it, disappeared Friday.
Last December, two teams of physicists working at CERN’s Large Hadron Collider reported that they might have seen traces of what could be a new fundamental constituent of nature, an elementary particle that is not part of the Standard Model that has ruled particle physics for the last half-century.
A bump on a graph signaling excess pairs of gamma rays was most likely a statistical fluke, they said. But physicists have been holding their breath ever since.
If real, the new particle would have opened a crack between the known and the unknown, affording a glimpse of quantum secrets undreamed of even by Einstein. Answers to questions like why there is matter but not antimatter in the universe, or the identity of the mysterious dark matter that provides the gravitational glue in the cosmos. In the few months after the announcement, 500 papers were written trying to interpret the meaning of the putative particle.
On Friday, physicists from the same two CERN teams reported that under the onslaught of more data, the possibility of a particle had melted away.
“We don’t see anything,” said Tiziano Camporesi of CERN, the European Organization for Nuclear Research and a spokesman for one of the detector teams known as C.M.S., on the eve of the announcement. “In fact, there is even a small deficit exactly at that point.”
His statement was echoed by a member of the competing team, known as Atlas. James Beacham, of Ohio State University, said, “As it stands now, the bumplet has gone into a flatline.”
“This is the success of science, this is what science does,” he added.
Dr. Camporesi said, “It’s disappointing because so much hype has been made about it.” But, he added, noting that the experimenters had always cautioned that the bump was most likely a fluke, “we have always been very cool about it.”
Collision Course
It was the longest, most costly manhunt in science for an elusive particle that was said to be key to the workings of the universe. For a generation of physicists, it was an appointment with history.
By Jeffery DelViscio, Catherine Spangler and Soo-Jeong Kang on March 4, 2013. Photo by Denis Balibouse/Reuters. Watch in Times Video »
The new results were presented in Chicago at the International Conference of High Energy Physics, ICHEP for short, by Bruno Lenzi of CERN for the Atlas team, and Chiara Rovelli for their competitors named for their own detector called C.M.S., short for Compact Muon Solenoid.
The presentations were part of an outpouring of dozens of papers from the two teams on the results so far this year from the collider, all of them in general agreement with the Standard Model.
The main news is that the collider, which had a rocky start, exploding back in 2008, is now running “swimmingly” in CERN’s words, producing up to a billion proton-proton collisions a second.
“We’re just at the beginning of the journey,” said Fabiola Gianotti, CERN’s director-general, in a statement.
But perhaps nature has not gotten the memo.
The non-result has further deepened an already deep mystery about the famous Higgs boson, which explains why other particles have mass, and whose discovery resulted in showers of champagne and Nobel Prizes four years ago.
The Higgs, one of the heaviest elementary particles known, weighs about 125 billion electron volts, in the units of mass and energy favored by particle physicists — about as much as an entire iodine atom. That, however, is way too light by a factor of trillions according to standard quantum calculations, physicists say, unless there is some new phenomenon, some new physics, exerting its influence on the universe and keeping the Higgs mass from zooming to cataclysmic scales. That would mean new particles.
“We have seen the Higgs, we expect to see something else,” said Lisa Randall, a Harvard particle theorist who was not part of the CERN experiments. Hence the excitement over the December bump. Its mass, about 750 billion electron volts, was in the range where something should happen.
“It would have been great if it was there,” Dr. Randall said. “It is the sort of thing they should be looking for if we want to understand the Higgs.”
It sounds simple: If something has a big carbon footprint and you get rid of it, you eliminate those carbon dioxide emissions. Right?
But it’s not always that easy. In a recent study published in The Journal of Industrial Ecology, researchers at the Center for Environmental Strategy at the University of Surrey in England estimated the annual carbon footprint of crime in England and Wales, and found that reducing crime could actually cause society’s overall carbon footprint of society to increase.
The findings illustrated the rebound effect, which describes how reducing the emissions of greenhouse gases in one area can lead to more emissions in the aggregate, because of direct or indirect effects. It’s something that policy makers have often been encouraged to consider when they set out to reduce emissions.
No comments:
Post a Comment