GeoLog

Imaggeo on Mondays

Imaggeo on Mondays: How do Earth’s Northern Lights form?

Imaggeo on Mondays: How do Earth’s Northern Lights form?

Aurora Borealis, which means Northern Lights are caused by electrically charged particles from the sun, which enter the Earth’s atmosphere and collide with gases such as oxygen and nitrogen. When the charged particles are blown towards the Earth by the solar wind, they are largely deflected by the Earth’s magnetic field. However, the Earth’s magnetic field is weaker at the poles and therefore some particles enter the Earth’s atmosphere and collide with gas particles. It has been found that in most instances northern and southern auroras are mirror-like images that occur at the same time, with similar shapes and colours.

Auroras can appear in many vivid colours, although green is the most common. Auroras can also appear in many forms, from small patches of light that appear out of nowhere to streamers, arcs, rippling curtains or shooting rays that light up the sky with an incredible glow. Ny Ålesund, Svalbard constitutes an ideal platform for observing and investigating Aurora Borealis thanks to the scarcity of anthropogenic light sources and the dark polar night sky.

This photo was kindly provided by Gregory Tran, who is going to be the AWIPEV Station Leader for the Overwintering period 2019-2020.

Description by Konstantina Nakoudi, as it first appeared on imaggeo.egu.eu

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: A lifeline between light and shadow

Imaggeo on Mondays: A lifeline between light and shadow

The Rapaälven making its way through the Rapadalen valley in Northern Sweden. After over a week of hiking through pure wilderness I reached the summit of Skierffe together with three friends. We were just blown away by the view and completely in awe for the beautiful shape of the rivers course… little lakes in between river channels of different sizes as well as dense vegetation forming a habitat for so many animals.. all controlled by erosion and the force of the water cycle…

A few days later we learned how difficult it is to hike through terrain like this for humans but how fast and quiet a moose can move right across the valley.

The Rapaälven is the biggest river in the Sarek National Park, the Swedish part of Lapland. Four smaller rivers (Smájllajåkkå, Mikkájåkkå, Guohperjåkkå, Áhkáåkkå) form this 75km long stream that drains around 30 different glaciers and the surrounding national park.

Description by Florian Konrad, as it first appeared on imaggeo.egu.eu

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: how short-term storms can impact our landscapes

Imaggeo on Mondays: how short-term storms can impact our landscapes

In the Sierra de Aconquija, a mountain range in the southern Central Andes of Argentina, strong storms often come and go at a moment’s notice, but they can have a long-lasting impact on the Earth’s surface.

The thunderstorm cell featured in this photo formed in less than half an hour, giving all those nearby only a few minutes to take cover. Mitch D’Arcy, a geomorphologist and postdoctoral researcher at the University of Potsdam and the GFZ German Research Centre for Geosciences, had the opportunity to witness this storm (and snap this picture!) while carrying out field work in the area.

“It was a spectacular experience, pouring heavy rain onto a very localised part of the mountain range, but it was also a hazard because the storm was quickly moving towards us with a lot of lightning. Without any trees around, we were likely targets for lightning strikes!” said D’Arcy. Luckily, he and his colleagues were able to find shelter in their truck while the huge downpour passed over them.

These kinds of thunderstorms are short-lived, but have intense precipitation rates. In this case, the temperature dropped by 14 degrees Celsius, and the storm was accompanied by heavy hail and lightning. And while these natural hazards are transient, they can have a long-term impact on the region’s landscape. Severe storms are capable of triggering landslides and floods and can relocate large amounts of sediment and debris in a short period of time.

D’Arcy is part of an international research programme called StRATEGy (Surface processes, Tectonics and Georesources: The Andean foreland basin of Argentina), which looks into how past and present climate change makes a mark on the terrain of the Argentine Andes, among other topics.

This research is essential for understanding and predicting how human-caused climate change will alter weather patterns and impact surface processes (such as how quickly sediments are eroded and transported across landscapes), according to D’Arcy. Having a better understanding of these surface processes and their sensitivity to the climate could help scientists better inform the public about how to prepare for natural hazards, such as flooding, erosion and landslides.

D’Arcy notes that it’s also important to assess how climate and weather trends will impact the sedimentary record, since it is one of the only physical records that scientists can use to examine how the Earth’s surface has change through time.

“North-western Argentina is a fascinating place to study how climate change affects surface processes, because it has experienced pronounced and abrupt changes in hydroclimate through time,” said D’Arcy. Their research has found that even subtle changes in the region’s climate have produced large changes to the surface environment, impacting how rivers take shape and how sediments move.

For example, while the Sierra de Aconquija is a semi-arid environment today, more than 12,000 years ago it used to be much wetter as a result of global climate changes. In fact, back then the mountain range was covered in glaciers and many of the basins were filled with lakes.

“It’s really important that we understand how different landscapes function and how they react to changes in climate. When we look at places like the southern Central Andes in Argentina, we find that the landscape records interesting signatures of ancient climate changes in Earth’s past. However, one of the big questions we still don’t have a good answer to, is how important are these very intense but rare storms for shaping landscapes and creating the sedimentary record from the geological past,” said D’Arcy.

By Olivia Trani, EGU Communications Officer

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: The salt mine carving into the Carpathians

Imaggeo on Mondays: The salt mine carving into the Carpathians

The image gives us a glimpse into the Slănic Salt Mine in central Romania, about 100 kilometres north of the capital city Bucharest. The region was actively mined for almost 30 years, from 1943 to 1970.

The Slănic Salt Mine is the largest salt mine in Europe, and the facility consists of 14 large chambers, each more than 50 metres high. The cavities of the mine, more than 200 metres deep, carve into the Southern Carpathian Mountains, offering a unique large-scale view into how the layers of rock beneath the Earth’s surface bend and fold. The structures featured in this image were stretched out over time as the Earth’s tectonic plates shifted, highlighting just how fluid our planet can be.

Compared to other rocks, the rock salts in this mine can change form and flow without much pressure and at relatively shallow depths. “This flow is however very slow, so that man-made cavities in salt mines deform very slowly and remain open for decades,” notes Janos Urai, a professor of structural geology, tectonics and geomechanics at RWTH Aachen University in Germany who snapped this image while visiting the mine in 2017. “We study this slow flow of salt in nature, to be able to improve predictions of the long-term evolution of nuclear waste repositories and abandoned salt caverns.

The mine is no longer used for resource extraction, but is now an active tourist destination (there are even playgrounds, pool tables and other recreational features).

By Olivia Trani, EGU Communications Officer

You can learn more about salt tectonics on the Tectonics and Structural Geology blog here:  Minds over Methods: Reconstruction of salt tectonic features

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.