The gullies on a Martian sand dune in this trio of images from NASA’s Mars Reconnaissance Orbiter deceptively resemble features on Earth that are carved by streams of water. However, these gullies likely owe their existence to entirely different geological processes apparently related to the winter buildup of carbon-dioxide frost.
Scientists at the University of Arizona, Tucson, and at Johns Hopkins University Applied Physics Laboratory, Laurel, Md., compared pairs of images from before and after changes in such dune gullies. They determined that the changes occur in Martian winter, during periods of carbon-dioxide frost, rather than during warmer seasons when frozen water, if present, might somehow melt and flow.
Each of the three images here shows an area about 1.2 kilometers (three-fourths of a mile) across. The dunes lie inside Matara Crater, at 49.4 degrees south latitude, 34.7 degrees east longitude. The images are portions of observations by the High Resolution Imaging Science Experiment (HiRISE) camera on the Mars Reconnaissance Orbiter. HiRISE took the top one on March 14, 2008, which was mid-autumn in Mars’ southern hemisphere, the middle one on July 9, 2009, in the first half of the next southern-Mars summer, and the bottom one on October 4, 2010, in the late part of the following (and most recent) winter season.
Illumination is from the upper left. Gullies run leftward downhill from a dune crest in the upper right corner.
Arrows indicate places where changes appeared between observations. Each year, the alcoves at the dune’s crest and the channel beds widened during the Martian winter as material moved down slope and lengthened the apron at the bottom. Very new deposits (formed sometime in September 2010) are visible in the bottom image as the darker material extending from the channels and obscuring the pre-existing ripples on the dune’s surface. Additionally, on the upper gully, material first filled-in part of the channel (between 2008 and 2009) and then re-incised the channel into the apron (between 2009 and 2010).
That’s what they say.
Continue reading Did you know that this is the year of the Republican Woman?
A settlement is in the works in Doe v. Mount Vernon Board of Education et al., the case in which John Freshwater, a Mount Vernon, Ohio, middle school science teacher, was accused of inappropriate religious activity in the classroom — including displaying posters with the Ten Commandments and Bible verses, branding crosses on the arms of his students with a high-voltage electrical device, and teaching creationism. The Mount Vernon News (October 27, 2010) reports that the parties have signed the agreement, which still must be approved by a judge.
If you are a teabagger or a Republican, don’t read below the fold. Just go away.
Continue reading The Oatmeal Experiment
US Representative to the House, District 3
I’m very familiar with Meffert’s stand on the issues, and agree with them fully.
State Senator District 47
Leo Foley is a centrist Democrat who has done a great job to date.
State Representative District 47A
Dittrich has been a great representative.
Mark Dayton/Yvonne Prettner Solon
Dayton will implement progressive Minnesota-like policies, and push for (or allow the legislature to develop) sane tax policies (i.e., tax the rich more, then get stuff done). The election is quite close, so every vote for Dayton counts, depending on what numbers you accept.
Secretary of State
Ritchie showed himself to be an excellent secretary of state during the … well, you remember, we need not speak of those days …
Otto is a progressive, conservation oriented highly competent auditor. Anderson, seeking to get her job back, was a moron. See this.
State Attorney General
Lori Swanson kicks ass as Attorney General
I picked Stuart based on his experience.
Close call. I’ve heard from people who know people who are people and Ive decided to support Johnson.
Soil and Water Conservation Districts 3 and 4
I am opposed to all of the candidates. I will write someone in. Any suggestions?
Mayor of Coon Rapids
Tim seems to have done a fine job, and the opposing candidate, Dave Nelson, has not allowed interviews or otherwise distributed information about himself as far as I can tell.
Interesting to look back at this now that the Arctic Ice Cap is opening up and disappearing:
A new NASA study shows that the rising frequency and intensity of arctic storms over the last half century, attributed to progressively warmer waters, directly provoked acceleration of the rate of arctic sea ice drift, long considered by scientists as a bellwether of climate change.
NASA researcher Sirpa Hakkinen of Goddard Space Flight Center in Greenbelt, Md., and colleagues from Woods Hole Oceanographic Institution, Woods Hole, Mass., and the Arctic and Antarctic Research Institute, St. Petersburg, Russia, set out to confirm a long-standing theory derived from model results that a warming climate would cause an increase in storminess. Their observational approach enabled them to not only link climate to storminess, but to also connect increasing trends in arctic storminess and the movement of arctic ice — the frozen ocean water that floats on the Arctic’s surface. Results from their study as well as what they could mean for future climate change appeared this month in the American Geophysical Union’s Geophysical Research Letters.
“Gradually warming waters have driven storm tracks — the ocean paths in the Atlantic and Pacific along which most cyclones travel — northward. We speculate that sea ice serves as the ‘middleman’ in a scenario where increased storm activity yields increased stirring winds that will speed up the Arctic’s transition into a body of turbulently mixing warm and cool layers with greater potential for deep convection that will alter climate further,” said Hakkinen. “What I find truly intriguing about confirming the link between the rise in storminess and increased sea ice drift is the possibility that new sinks for carbon dioxide may emerge from this relationship that could function as negative feedback for global warming.”
Hakkinen and colleagues analyzed 56 years of storm track data from earlier studies and annual data on atmospheric wind stress, an established indicator of storm activity, that is generated by the National Center for Atmospheric Research in Boulder, Colo. The data confirmed an accelerating trend in storm activity in the Arctic from 1950 to 2006. Acknowledging ice as a harbinger of climate change, they next analyzed ice drift data collected during the same 56-year period from drifting stations and after 1979 from drifting buoys positioned around the Arctic that measured surface air temperature and sea level pressure.
Hat tip: Todd.
… and I thought I’d share it with you …
Continue reading My close personal friend Al Franken just sent me this personal private letter