GeoLog

clouds

Imaggeo on Mondays: Inside the whale’s mouth

Imaggeo on Mondays: Inside the whale’s mouth

Often there are moments in our lives when we are reminded of the strength and magnitude of our environment, whether that’s trekking through a mountain range or gazing at the horizon from the ocean shore. Yet arguably there are few things that can make you feel as small as a particularly powerful summer storm.

“The atmosphere is undoubtedly one of the most dynamic components in the Earth System. Nothing can demonstrate the power of nature to an observer as well as a strong thunderstorm rolling in,” said Michiel Baatsen, a climate researcher at Utrecht University in the Netherlands who snapped this week’s featured photo. Besides being a climate researcher, Baatsen is also a weather enthusiast and storm chaser, fascinated by severe weather and thick towering cloud formations.

He and a team of friends will often hit the road, travelling across Western Europe in pursuit of extreme thunderstorms that pass the continent. “In these ventures, we try to capture some inspiring scenes and have been amazed many times by the things we end up seeing,” said Baatsen.

This photo was taken in June last year while Baatsen was traveling through the northeastern corner of the Netherlands. He and his friends were searching for a thunderstorm that had crossed the border from Germany, but the local humidity was relatively high, making visibility too poor to properly locate the approaching storm. “After several failed attempts to locate the approaching storms, we realised the conditions were so hazy that they completely obscured the leading cloud structures,” said Baatsen. But once the first clouds passed overhead, the conditions suddenly changed and the sky became clearer, revealing a dramatic view of the storm.

If you feel as if the storm feature in the photo is about to engulf you, you’re not alone. This kind of cloud structure is called a shelf cloud, but it’s also often referred to as a ‘whale’s mouth’, since the formations often give the impression of being consumed by a giant whale.

‘Whale’s mouth’ clouds take shape when cold, dense air surging out of a thunderstorm collides with warm air entering the storm. When the two currents make contact, the air goes upward and condenses into a thick sheet of clouds. This kind of formation appears at the leading edge of a thunderstorm, a harbinger to the incoming rainfall.

For Baatsen and his colleagues, the storm offered a short window between its first gusts and the subsequent rainfall, allowing them to observe this natural phenomenon. “With the whale’s mouth being overhead, there was a brief moment to appreciate this scene during which one was basically trapped in a cage surrounded by the rain rolling in on one side and the haze drawing away on the other side,” said Baatsen.

By Olivia Trani, EGU Communications Officer

Imaggeo on Mondays: Cumulonimbus, king of clouds

Imaggeo on Mondays: Cumulonimbus, king of clouds

This wonderful mature thunderstorm cell was observed near the German Aerospace Center (DLR) Oberpfaffenhofen. A distinct anvil can be seen in the background meanwhile a new storm cell is growing in the foreground of the cumulonimbus structure. Mature storm cells like this are common in Southern Germany during the summer season. Strong heat, enough moisture, and a labile stratification of the atmosphere enables the development of this exciting weather phenomenon.

Description by Martin Köhler, 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: Refuge in a cloudscape

Imaggeo on Mondays: Refuge in a cloudscape

The action of glaciers combined with the structure of the rock to form this little platform, probably once a small lake enclosed between a moraine at the mountain side and the ice in the valley.

Now it has become a green haven in the mountain landscape, a perfect place for an alp. In the Alps, stratus clouds opening up on autumn mornings often create gorgeous light display.

That day, some of the first light landed on this exact spot, while the mountain shadows still covered the valley bottom.

Description by Julien Seguinot, as it first appeared on imaggeo.egu.eu

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submittheir 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/.

Extraordinary iridescent clouds inspire Munch’s ‘The Scream’

Screaming clouds

Edvard Munch’s series of paintings and sketches ‘The Scream’ are some of the most famous works by a Norwegian artist, instantly recognisable and reproduced the world over. But what was the inspiration behind this striking piece of art?

The lurid colours and tremulous lines have long been thought to represent Munch’s unstable state of mind; a moment of terror caught in shocking technicolour. At the same time, scientists have recently identified the connection between the great works of artists such as William Turner and the red and orange sunsets which can be a result of the global impact of volcanic aerosols. However, research presented this week at the European Geosciences Union General Assembly in Vienna by atmospheric scientists in Oslo Norway, suggests that the painting might show us evidence of something much stranger, and rarer – nacreous clouds.

Nacreous or mother-of-pearl clouds, are an extremely rare form of cloud created 20-30km above sea level – in the polar stratosphere when the air is extremely cold (between -80 and -85 degrees centigrade) and exceptionally humid,. So far observed mostly in the Scandinavian countries, these clouds are formed of microscopic and uniform particles of ice, orientated into thin clouds. When the sun is below the horizon (before sunrise or after sunset), these clouds are illuminated in a surprisingly vibrant way blazing across the sky in swathes of red, green, blue and silver. They have a distinctive wavy structure as the clouds are formed in the lee-waves behind mountains.

In 2014, these clouds were seen again over the skies of Oslo and given their extreme colouration and unexpected appearance, a photographer, Svein Fikke, immediately thought of Munch’s work. This perceived similarity between the mother of pearl clouds and the striking clouds and sense of tension in the painting is only reinforced when reading Munch’s writings about his experiences on the day that inspired the painting.

“I went along the road with two friends – the sun set

I felt like a breath of sadness –

– The sky suddenly became bloodish red

I stopped, leant against the fence, tired to death – watched over the

Flaming clouds as blood and sword

The city – the blue-black fjord and the city

– My friends went away – I stood there shivering from dread – and

I felt this big, infinite scream through nature”

                            Edvard Munch’s Diary Notes 1890-1892 (Tøjner and Gundersen, 2013)

Scientists have, in the past, used artworks to infer environmental conditions; from paintings of the ‘frost fairs’ held on the River Thames that show the gradual environmental change in Europe, to the discovery that several artists depict the influence of volcanic aerosols on global atmosphere in their paintings.

In a study conducted in 2007 (and 2014), scientists found that the visible impact that volcanic aerosols have on the atmosphere has in fact been recorded in the works of many of the great masters – particularly William Turner (Zerefos et al, 2007)). Several of Turner’s paintings depict sunsets with a distinct red/orange hue, distinct from his usual work of other years. This was correlated with significant volcanic eruptions in the same time period and the researchers found that these reddish paintings were all created in the years of, or immediately following, a major eruption (shown in the graph below).

Graph to show the relationship between colour and volcanic aerosols (a)The mean annual value of R/G measured on 327 paintings. (b)The percentage increase from minimum R/G value shown in (a). (c)The corresponding Dust Veil Index (DVI). The numbered picks correspond to different eruptions as follows: 1. 1642 (Awu, Indonesia-1641), 2. 1661 (Katla, Iceland-1660), 3. 1680 (Tongkoko and Krakatau, Indonesia-1680), 4. 1784 (Laki, Iceland-1783), 5. 1816 (Tambora, Indonesia-1815), 6. 1831 (Babuyan, Philippines-1831), 7. 1835 (Coseguina, Nicaragua-1835). 8. 1883 (Krakatau, Indonesia-1883). From Zerefos et al (2007).

For many years ‘The Scream’ was thought to also show the influence of a volcanic eruption, most likely the catastrophic eruption of Krakatoa in 1883 (described here by Volcanologist David Pyle), but whereas volcanic skies tend to tint the whole sky a red/orange, the skies in the scream have a distinct pattern, only seen in these extremely rare nacreous clouds.

How rare are they? Well, researcher Dr Helene Muri, a researcher based at the University of Oslo, who presented the research at the press conference, said that in her lifetime living mostly in Norway as an atmospheric researcher she has only seen them once. And what about Munch’s feeling of dread and ‘breath of sadness’?

Well, having a glowing swathe of iridescent petrol coloured clouds flare into bright relief after sunset, only for them to disappear 30 minutes later would be pretty shocking for any of us, even in our modern days of fluorescent streetlamps and light polluted skies.

By Hazel Gibson, EGU Press Assistant at the EGU 2017 General Assembly