GeoLog

Imaggeo

Imaggeo on Mondays: White rainbow in the Arctic

“Above the foggy strip, this white arch was shining, covering one third of the visible sky in the direction of the ship's bow,” he explains. “It was a so-called white, or fog rainbow, which appears on the fog droplets, which are much smaller then rain droplets and cause different optic effects, which is a reason of its white colour.”

Despite heading into the long polar night – the time when the sun doesn’t shine in the globe’s most northerly latitudes and when temperatures drop and thick sheets of sea ice form -the Arctic is reported to be 20° C warmer than average for this time of year.  Never has it been more important to understand the effects of climate change on Polar Regions.

Mikhail Varentsov, a climate and meteorology expert from the University of Moscow, was on board the Akademik Tryoshnikov research vessel during its scientific cruise, NABOS (Nansen and Amundsen Basin Observation System), in 2015.

“During the cruise we went through five Arctic seas from Arkhangelsk city in Russia to the latitude of 180 degrees East,” explains Mikhail.

The aim of the cruise was to collect oceanographic and meteorological data of the icy waters of the Arctic. The data would be used to gain an increased understanding of the challenges faced by the region due to rising temperatures. There was a particular focus on understanding what role warm Atlantic water plays in climate change in the Arctic.

“I was in the group responsible for measurements of parameters of sea and atmosphere interaction – heat and momentum fluxes, compounds of heat balance, cloudiness, etc., and during my watch I had to go to the upper deck to make observations about cloudiness and to check the state of our measurement equipment,” explains Mikhail.

Grey days, with total cloud cover were a common theme throughout the expedition – typical of the Arctic sea summer. But on an unusually clear day, with just a few fog patches in the horizon and remarkably cold water temperatures, Mikhail headed out to take his cloudiness measurements and was rewarded with an extraordinary view.

“Above the foggy strip, this white arch was shining, covering one third of the visible sky in the direction of the ship’s bow,” he explains. “It was a so-called white, or fog rainbow, which appears on the fog droplets, which are much smaller then rain droplets and cause different optic effects, which is a reason of its white colour.”

Despite the gruelling conditions and challenges of working in such a remote region, Mikhail feels privileged, “this trip made me love the simple and fragile beauty of the Arctic, however, this particular scene, with white rainbow above the ice was one of my strongest impressions from the trip.”

By Laura Roberts, 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: Isolated storm

Imaggeo on Mondays: Isolated storm

Clouds and storms are formed when warm, moist air rises. This causes the air to expand and cool: forming clouds as the moisture condenses onto particles suspended in the air (called cloud condensation nuclei). Normally, air rises from surface heating, or when warm and cold air pockets collide, or if air is pushed upwards when passing over hills or mountains. If this heating, and subsequent rising, is rapid enough then thunderstorms can form.

This imaggeo on Mondays photo shows an isolated thunderstorm roughly 50 km North of Vienna. The difference between an isolated thunderstorm and scattered storms is how much coverage the clouds have over a given area. If less than 10-20 % is covered then these storms are described as isolated. Scattered storms occur when coverage is at least 30-50 %. These storms can lead to downpours lasting a few minutes that then leads to sunny spells, only to have another rain storm occur again shortly afterwards.1

Globally, there are roughly 16 million thunderstorms each year, and at any given moment, there are ~2,000 thunderstorms in progress.2 The visible dark grey anvil shape and the fact that the lighter clouds above appear to be being ‘pulled into’ the storm suggests that this is a ‘severe’ thunderstorm. This means that the storm is self-supporting3 and can cause more extreme impacts than a normal thunderstorm. Rainfall is more intense and can cause flash flooding. In some cases, hail over 2.5 cm large can fall and tornados can even be formed.4 For more information about severe thunderstorms please check out the further reading list below.

By Sarah Connors, EGU Science Policy Officer

Further reading / sources

[1] – Aerostorms Scattered vs. Thunderstorms – http://www.aerostorms.com/scattered-vs-isolated-thunderstorms-what-is-the-difference/

[2] – Thunderstorm Basics – http://www.nssl.noaa.gov/education/svrwx101/thunderstorms/

[3] – Royal Meteorological Society Thunderclouds presentation – http://www.met.reading.ac.uk/~sgs02rpa/CONTED/WEATHER09_thunder.pdf

[4] – Frequently Asked Questions About Thunderstorms – http://www.nssl.noaa.gov/education/svrwx101/thunderstorms/faq/

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: Aoraki & a round-up of the latest New Zealand earthquake news

Imaggeo on Mondays: Aoraki & a round-up of the latest New Zealand earthquake news

On Sunday the 13th November, New Zealand’s South Island was struck by a powerful 7.8 M earthquake. Initial analysis by the United States Geological Survey (USGS) indicates that the source of the tremor was faulting on or near the boundary between the Pacific and Australia plates. A tsunami alert (no longer active) was triggered following the earthquake, with risk of tsunami waves along coastal areas. The maximum wave high recorded by a gauge at Kaikoura, 181 km north of Christchurch, was 2.5m, according to Weatherwatch.co.nz.

The collision of the two plates is also responsible for the formation of the Alpine Fault, which runs along the western flank of the Southern Alps, (Kā Tiritiri o te Moana). The mountain range runs 500km along the South Island, explains Katrina Sauer on our open access image repository, Imaggeo.  In addition, the Alpine Fault is responsible for the uplift of this impressive mountain range. Sunkissed by a setting sun (pictured above), Aoraki/Mt. Cook is the highest mountain in New Zealand (3,724 m). Katrina took the beautiful picture from Mueller Hut.

For more information about yesterday’s earthquake, as well as photographs which depict the staggering aftermath of the tremors see the list of links below (by no means exhaustive):

For some of the latest news about the earthquake, you might also follow the #eqnz  and  #nzearthquake on Twitter. For details about New Zealand geology and why and how it’s tremors are triggered, you can follow Chris Rowan  (@Allochthonous), Jascha Polet (@CPPGeophysics), @IRIS_EPO (particularly good for teaching resources for kids), and Anthony Lomax (@ALomaxNet) (among many other  great scientists!).

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/.

Follow

Get every new post on this blog delivered to your Inbox.

Join other followers: