Tag Archives: upper atmosphere

Jupiter’s Red Spot is Likely a Sunburn, Not a Blush

The ruddy color of Jupiter’s Great Red Spot is likely a product of simple chemicals being broken apart by sunlight in the planet’s upper atmosphere, according to a new analysis of data from NASA’s Cassini mission. The results contradict the other leading theory for the origin of the spot’s striking color — that the reddish chemicals come from beneath Jupiter’s clouds. (more…)

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Scientists solve a decades-old mystery in the Earth’s upper atmosphere

New research published in the journal Nature resolves decades of scientific controversy over the origin of the extremely energetic particles known as ultra-relativistic electrons in the Earth’s near-space environment and is likely to influence our understanding of planetary magnetospheres throughout the universe.

Discovering the processes that control the formation and ultimate loss of these electrons in the Van Allen radiation belts — the rings of highly charged particles that encircle the Earth at a range of about 1,000 to 50,000 kilometers above the planet’s surface — is a primary science objective of the recently launched NASA Van Allen Probes mission. Understanding these mechanisms has important practical applications, because the enormous amounts of radiation trapped within the belts can pose a significant hazard to satellites and spacecraft, as well astronauts performing activities outside a craft. (more…)

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How did a third radiation belt appear in the Earth’s upper atmosphere?

Since the discovery of the Van Allen radiation belts in in the Earth’s upper atmosphere in 1958, space scientists have believed that these belts consisted of two doughnut-shaped rings of highly charged particles — an inner ring of high-energy electrons and energetic positive ions, and an outer ring of high-energy electrons.

However, in February of this year, a team of scientists reported in the journal Science the surprising discovery of a previously unknown third radiation ring. This narrow ring had briefly circled the Earth between the inner and outer rings in September 2012 and then almost completely disappeared.

How did this temporary radiation belt appear and dissipate? (more…)

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Freezing Electrons in Flight

Using the world’s fastest laser pulses, which can freeze the ultrafast motion of electrons and atoms, UA physicists have caught the action of molecules breaking apart and electrons getting knocked out of atoms. Their research helps us better understand molecular processes and ultimately be able to control them in many possible applications.

In 1878, a now iconic series of photographs instantly solved a long-standing mystery: Does a galloping horse touch the ground at all times? (It doesn’t.) The images of Eadweard Muybridge taken alongside a racetrack marked the beginning of high-speed photography.

Approximately 134 years later, researchers in the University of Arizona department of physics have solved a similar mystery, one in which super-excited oxygen molecules have replaced the horse, and ultrafast, high-energy laser flashes have replaced Muybridge’s photo emulsion plates. (more…)

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Upper Atmosphere Facilitates Changes That Let Mercury Enter Food Chain

Humans pump thousands of tons of vapor from the metallic element mercury into the atmosphere each year, and it can remain suspended for long periods before being changed into a form that is easily removed from the atmosphere.

New research shows that the upper troposphere and lower stratosphere work to transform elemental mercury into oxidized mercury, which can easily be deposited into aquatic ecosystems and ultimately enter the food chain. (more…)

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GPS Stations Can Detect Clandestine Nuclear Tests

VIENNNA, Austria – At the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) meeting, American researchers are unveiling a new tool for detecting illegal nuclear explosions: the Earth’s global positioning system (GPS).

Even underground nuclear tests leave their mark on the part of the upper atmosphere known as the ionosphere, the researchers discovered, when they examined GPS data recorded the same day as a North Korean nuclear test in 2009. Within minutes on that day, GPS stations in nearby countries registered a change in ionospheric electron density, as a bubble of disturbed particles spread out from the test site and across the planet. (more…)

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Climate Change From Black Carbon Depends on Altitude

Palo Alto, CA — Scientists have known for decades that black carbon aerosols add to global warming. These airborne particles made of sooty carbon are believed to be among the largest man-made contributors to global warming because they absorb solar radiation and heat the atmosphere. New research from Carnegie’s Long Cao and Ken Caldeira, along with colleagues George Ban-Weiss and Govindasamy Bala, quantifies how black carbon’s impact on climate depends on its altitude in the atmosphere. Their work, published online by the journal Climate Dynamics, could have important implications for combating global climate change. (more…)

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Plasma Jets are Suspect in Solar Mystery

*Scientists take new look at solar corona* 

One of the most enduring mysteries in solar physics is why the Sun’s outer atmosphere, or corona, is millions of degrees hotter than its surface.

Now scientists believe they have discovered a major source of hot gas that replenishes the corona: jets of plasma shooting up from just above the Sun’s surface. (more…)

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