Archive | December, 2011

Imaggeo on Mondays: Sky-high dancing lights

26 Dec

Sky high by Taro Nakai, distributed by EGU under a Creative Commons licence.

This photo, taken in early 2011 at Murphy Dome, a mountain in Fairbanks North Star Borough in the US state of Alaska, shows a beautiful natural phenomena known as aurora.

Auroras, also called northern lights in the Northern Hemisphere, are stunning light displays visible mainly at high latitudes. There, it is easier for energetic particles from the Earth’s magnetosphere and solar wind to follow the planet’s magnetic field lines and collide with atoms of gas in the atmosphere. These interactions release photons of different colours, depending on the gas the energetic particles interact with. The result? Awe-inspiring colourful curtains of light dancing in the skies.

The photographer, Taro Nakai, is a micrometeorologist at the International Arctic Research Center, University of Alaska Fairbanks. He took this shot for a beautiful time-lapse movie, available from his YouTube channel.

“Murphy Dome has an elevation of 776 meters, and since it is located in a cold subarctic area, the top of this mountain is so-called alpine tundra. Therefore, there are no tall trees and we can see the unobstructed view of the spectacular northern lights,” said Nakai.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

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Imaggeo on Mondays: Volcanic twilight

19 Dec

Volcanic twilight by Robin Campion, distributed by EGU under a Creative Commons licence.

Mount Etna, located in the east coast of Sicily in Italy, is one of the most active volcanos in the world and is home to spectacular eruptions. This photo, taken by Robin Campion from the Université Libre de Bruxelles in Belgium, shows bright-red lava and a smoking scoria cone on the upper east flank of the volcano during an eruption in 2006.

“Fast-flowing lava flow was erupted from an eastwards trending fissure connected to the southeast crater. The crater itself was subject to short-lived (a few hours) episodes of intense explosive activity, separated by 2-3 days of repose and mild ash emissions,” Campion described.

Interestingly, the scoria cone seen in the picture is now buried under several meters of lava erupted this year by the southeast crater.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Imaggeo on Mondays: Lonely Tree

12 Dec

The Lonely tree. Image by Alexandre M. Ramos , distributed by EGU under a Creative Commons licence.

The photograph was taken near to Üetliberg in Switzerland. The Üetliberg mountain is close to Zurich and part of the Albis mountain range.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Meet EGU at the American Geophysical Union Fall Meeting

5 Dec

Are you attending the AGU Fall Meeting in San Francisco 5th-9th December? If so come and visit the EGU booth in the Exhibition Hall Tuesday, 6 December – Thursday, 8 December 0930h – 1800h and Friday, 9 December 0930h – 1330h in Booth 1428, near the AGU Marketplace. You can search a map of the exhibition hall online.

In attendance will be the Executive Secretary, the current Science Communications Postdoctoral Fellow and the Media and Communications Officer of the European Geosciences Union.

Imaggeo on Mondays: Forest Fires

5 Dec

Forest Fires. Image by Sandro Makowski, distributed by EGU under a Creative Commons licence.

Slash and burn activity in Southern Ecuador. The photo was the taken during field work at the San Francisco valley, a microcatchment in the province of Zamora, south-east of Ecuador. The valley is the study area of the DFG research unit FOR 816 “Biodiversity and Sustainable Management of a Megadiverse Tropical Mountain Ecosystem”.

The picture shows firemen trying to fight a forest fire which went out of control soon after its ignition by local farmers. As usual, every year thousands of hectares of forests are burned in the Amazon during the dry season. This burn event took place in November 2010, which was a particularly dry year in the Amazon.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Geosciences column: Why are jet streams not good wind energy sources?

2 Dec

Commercial airlines know jet streams well. Planes often hitch a ride on these strong, high-altitude atmospheric winds, which blow from west to east, to fly faster, and they are the reason why long-haul easterly flights (such as those between the US and Europe) are quicker than the corresponding westerly journeys.

Scientists are also familiar with these fierce and persistent winds, which occur at altitudes of 7 to 16 kilometres and have velocities from 90 to several hundred kilometres per hour. Some have even suggested we could harvest wind power from jet streams by developing appropriate airborne technology such as large kite-like wind-power generators. A group of researchers from the US and Australia estimated in 2007 that this potential renewable energy source could provide roughly 100 times the global demand of energy.

But research published this week in Earth System Dynamics, a journal of the European Geosciences Union, challenges this assumption. Lee Miller and collaborators from the Max Planck Institute for Biogeochemistry in Jena, Germany, calculated the maximum extractable energy from these streams to be about 200 times less than previously reported. They also warned that extracting wind power in this way can result in significant climate impacts.

Airborne wind-power generators: to remain science fiction? (Source: AlphaGalileo)

The scientists pointed out that the high velocities of jet streams are not the result of a strong power source but are consequence of the near absence of friction high up in the atmosphere, as it is well-known in meteorology. The group shows in their calculations that, in fact, it takes very little power to accelerate and sustain these winds.

“It is this low energy generation rate that ultimately limits the potential use of jet streams as a renewable energy resource,” said Axel Kleidon, the study’s leader, in a press release.

A maximum of 7.5 terawatts (7.5 trillion watts), less than half of the 2010 global energy demand of 17 terawatts, can be extracted from jet streams, they determined. Previous studies arrived at much higher values because they used the wind velocity to estimate wind power, a method the Max-Planck researchers claim is flawed.

As with other weather systems, jet streams are in part caused by the fact that equatorial regions are warmer than the poles, which are less strongly heated by the sun. The differences in temperature and air pressure between these regions drive the atmosphere into motion creating the strong winds. These differences, rather than wind speeds, are what controls how much of the generated wind can be used as an energy resource.

The authors also estimated the climate impacts of extracting energy from jet streams. Wind turbines build up resistance when harvesting energy, which alters the flow of the wind. This disruption can slow down the entire climate system of our planet when substantial amounts of energy are extracted.

If 7.5 terawatts of energy were extracted from jet streams “the atmosphere would generate 40 times less wind energy than what we would gain from the wind turbines,” said Miller in a press release.

“This results in drastic changes in temperature and weather.”

By Bárbara Ferreira, EGU’s Media and Communications Officer