|Professor Peter Wadhams on albedo changes in the Arctic|
The images below illustrate extremely high temperatures forecast to hit Russia on June 6, 2015.
A temperature of 29.4°C (84.92°F) is forecast for the location at the green circle for June 6, 2015. The location is close to the Arctic Ocean and to rivers ending in the Arctic Ocean, as also shown on the image below.
The location, at a latitude of 66.48°N, is approximately on the Arctic Circle, which runs 66°33′45.8″ north of the Equator. North of the Arctic Circle, the sun is above the horizon for 24 continuous hours at least once a year.
The many hours of sunshine make that, during the months June and July, insolation in the Arctic is higher than anywhere else on Earth, as shown on above image, by Pidwirny (2006).
The size of the June snow and ice cover is so vitally important as insolation in the Arctic is at its highest at the June Solstice.
The Wikipedia image on the right calculates the theoretical daily-average insolation at the top of the atmosphere, where θ is the polar angle of the Earth's orbit, and θ = 0 at the vernal equinox, and θ = 90° at the summer solstice; φ is the latitude of the Earth.
The calculation assumed conditions appropriate for 2000 A.D.: a solar constant of S0 = 1367 W m−2, obliquity of ε = 23.4398°, longitude of perihelion of ϖ = 282.895°, eccentricity e = 0.016704.
Snow and ice cover on land can take up a large area, even larger than sea ice. In May 2015, the area of snow extent on the Northern Hemisphere was 17 million square km, while sea ice extent in May 2015 was below 13.5 million square km.
The chart below shows the decline of snow cover on land on the Northern Hemisphere in Spring over the years.
High temperatures over the Arctic Ocean are heating up the snow cover on land and the sea ice from above. High temperatures also set the scene for wildfires that can emit huge amounts of pollutants, including dust and black carbon that, when settling on the sea ice, can cause its reflectivity to fall. Rivers furthermore feed warm water into the Arctic Ocean, further heating up the sea ice from below.
The image below shows Arctic sea ice extent at June 3, 2015, when Arctic sea ice extent was merely 11.624 million square kilometers, a record low for the time of the year since satellite started measurements in 1979.
Sea ice melting occurs due to heat from above, i.e. absorbed sunlight. Once the sea ice is gone, energy from sunlight that previously went into melting and transforming ice into water, will instead go into warming up the Arctic Ocean and the sediments under the seafloor.
In addition, sea ice is also melting due to heat from below. Much of this heat is carried by the Gulf Stream and by rivers into the Arctic Ocean. Once the sea ice is gone, all this heat will go into warming up the Arctic Ocean and the sediments under the seafloor.
The sea ice acts as a heat buffer by absorbing energy in the process of melting. In other words, as long as there is sea ice, it will absorb heat and this will prevent this heat from raising the temperature of the water in the Arctic. Once the sea ice is gone, this latent heat must go elsewhere.
As the sea ice heats up, 2.06 J/g of heat goes into every degree Celsius that the temperature of the ice rises. While the ice is melting, all energy (at 334J/g) goes into changing ice into water and the temperature remains at 0°C (273.15K, 32°F).
Once all ice has turned into water, all subsequent heat goes into heating up the water, at 4.18 J/g for every degree Celsius that the temperature of water rises.
The amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C. The energy required to melt a volume of ice can raise the temperature of the same volume of rock by 150º C.
Decline of Arctic sea ice means that a lot more heat will be absorbed by the Arctic Ocean.
Thick sea ice covered with snow can reflect as much as 90% of the incoming solar radiation. After the snow begins to melt, and because shallow melt ponds have an albedo (or reflectivity) of approximately 0.2 to 0.4, the surface albedo drops to about 0.75. As melt ponds grow and deepen, the surface albedo can drop to 0.15, while the ocean reflects only 6% of the incoming solar radiation and absorbs the rest.
As Professor Peter Wadhams, University of Cambridge, once calculated, a collapse of the sea ice would go hand on hand with dramatic loss of snow and ice cover on land in the Arctic. The albedo change resulting from the snowline retreat on land is similarly large as the retreat of sea ice, so the combined impact could be well over 2 W/sq m. To put this in context, albedo changes in the Arctic alone could more than double the net radiative forcing resulting from the emissions caused by all people of the world, estimated by the IPCC to be 1.6 W/sq m in 2007 and 2.29 W/sq m in 2013.
Saturday, June 6, 2015
Artic News -- High Temperatures in the Arctic
SUBTITLES IN ENGLISH, ESPAÑOL, PORTUGUÊS
Click upon the circle after the small square for captions
How to Digitally Record/Video a UFO sighting:
Como registar digitalmente ou gravar um vídeo de um avistamento de um UFO:
Stabilize the camera on a tripod. If there is no tripod, then set it on top of a stable, flat surface. If that is not possible lean against a wall to stabilize your body and prevent the camera from filming in a shaky, unsteady manner.
Estabilize a camera com um tripé. Se não tiver um tripé, então coloque-a em cima de uma superfície estável. Se não for possível, então encoste-se a uma parede para estabilizar o corpo e evitar que a camera registe de maneira tremida e instável.
Provide visual reference points for comparison. This includes the horizon, treetops, lampposts, houses, and geographical landmarks (i.e., Horsetooth Reservoir, Mt. Adams, etc.) Provide this in the video whenever is appropriate and doesn’t detract from what your focus is, the UFO.
Forneça pontos visuais de referência para comparação. Isso inclui o horizonte, cimo das árvores, postes de iluminação, pontos de referência geográficos (como o Reservatório de Horsetooth, Mone Adams, etc) Forneça esses pontos no vídeo sempre que for apropriado e não se distraia do que é o seu foco, o UFO/a Nave.
Narrate your videotape. Provide details of the date, time, location, and direction (N,S,E,W) you are looking in. Provide your observations on the weather, including approximate temperature, windspeed, any visible cloud cover or noticeable weather anomalies or events. Narrate on the shape, size, color, movements, approximate altitude of the UFO, etc and what it appears to be doing. Also include any unusual physical, psychological or emotional sensations you might have. Narrate any visual reference points on camera so they correlate with what the viewer will see, and thereby will be better able to understand.
Faça a narração do vídeo. Forneça pormenores sobre a data, hora, local e direcção (Norte, Sul, Este, Oeste) que está a observar. Faça observações sobre as condições atmosféricas, incluindo a temperatura aproximada, velocidade do vento, quantidade de nuvens, anomalias ou acontecimentos meteorológicos evidentes. Descreva a forma, o tamanho, a cor, os movimentos, a altitude aproximada onde se encontra o UFO/nave, etc e o que aparenta estar a fazer. Inclua também quaisquer aspectos pouco habituais de sensações físicas, psicológicas ou emocionais que possa ter. Faça a narração de todos os pontos de referência visual que o espectador irá ver e que, deste modo, será capaz de compreender melhor.
Be persistent and consistent. Return to the scene to videotape and record at this same location. If you have been successful once, the UFO sightings may be occurring in this region regularly, perhaps for specific reasons unknown, and you may be successful again. You may also wish to return to the same location at a different time of day (daylight hours) for better orientation and reference. Film just a minute or two under “normal” circumstances for comparison. Write down what you remember immediately after. As soon as you are done recording the experience/event, immediately write down your impressions, memories, thoughts, emotions, etc. so it is on the record in writing. If there were other witnesses, have them independently record their own impressions, thoughts, etc. Include in this exercise any drawings, sketches, or diagrams. Make sure you date and sign your documentation.
Seja persistente e não contraditório. Volte ao local da cena e registe o mesmo local. Se foi bem sucedido uma vez, pode ser que nessa região ocorram avistamentos de UFOs/naves com regularidade, talvez por razões específicas desconhecidas, e talvez possa ser novamente bem sucedido. Pode também desejar voltar ao mesmo lugar a horas diferentes do dia (durante as horas de luz)para ter uma orientação e referência melhor. Filme apenas um ,inuto ou dois em circunstâncias “normais” para ter um termo de comparação. Escreva tudo o que viu imediatamente após o acontecimento. Logo após ter feito o registo da experiência/acontecimento, escreva imediatamente as impressões, memórias, pensamentos, emoções, etc para que fiquem registadas por escrito. Se houver outras testemunhas, peça-lhes para registar independentemente as suas próprias impressões, pensamentos, etc. Inclua quaisquer desenhos, esbolos, diagramas. Certifique-se que data e assina o seu documento/testemunho.
Always be prepared. Have a digital camera or better yet a video camera with you, charged and ready to go, at all times. Make sure you know how to use your camera (and your cell phone video/photo camera) quickly and properly. These events can occur suddenly, unexpectedly, and often quite randomly, so you will need to be prepared.
Esteja sempre preparado, Tenha sempre uma camera digital, melhor ainda, uma camera vídeo consigo, carregada e pronta a usar sempre que necessário. Certifique-se que sabe como lidar com a sua camera (ou com o seu celular/camera fotográfica) rápida e adequadamente. Esses acontecimentos podem acontecer súbita e inesperadamente e, por vezes, acidentalmente, por isso, necessita estar preparado.
Look up. Be prepared. Report. Share.
Olhe para cima, Esteja preparado, Relate, Partilhe.
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