NOTÍCIAS
13/05/2015 16:14 -03 | Atualizado 26/01/2017 22:12 -02

A Terra faz um zumbido estranho e agora conhecemos a causa

www.weather.gov webpage. GOES satellites provide the kind of continuous monitoring necessary for intensive data analysis. Geostationary describes an orbit in which a satellite is always in the same position with respect to the rotating Earth. This allows GOES to hover continuously over one position on Earth's surface, appearing stationary. As a result, GOES provide a constant vigil for the atmospheric "triggers" for severe weather conditions such as tornadoes, flash floods, hail storms and hurricanes.For updated information about the storm system, visit NOAA's WPC website: www.hpc.ncep.noaa.gov/For more information about GOES satellites, visit: www.goes.noaa.gov/ or goes.gsfc.nasa.gov/Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team NASA image use policy.NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission.Follow us on TwitterLike us on FacebookFind us on Instagram" data-caption="The monster winter storm that brought icing to the U.S. southeast moved northward along the Eastern Seaboard and brought snow, sleet and rain from the Mid-Atlantic to New England on February 13. A new image from NOAA's GOES satellite showed clouds associated with the massive winter storm stretch from the U.S. southeast to the northeast.Data from NOAA's GOES-East satellite taken on Feb. 13 at 1455 UTC/9:45 a.m. EST were made into an image by NASA/NOAA's GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Md. The clouds and fallen snow data from NOAA's GOES-East satellite were overlaid on a true-color image of land and ocean created by data from the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA's Aqua and Terra satellites.The image showed that the clouds associated with the storm were blanketing much of the U.S. East Coast.At 3:11 a.m. EST, a surface map issued by the National Weather Service or NWS showed the storm's low pressure area was centered over eastern North Carolina. Since then, the low has continued to track north along the eastern seaboard. By 11 a.m. EST, precipitation from the storm was falling from South Carolina to Maine, according to National Weather Service radar. By 11 a.m. EST, the Washington, D.C. region snow and sleet totals ranged from 3" in far eastern Maryland to over 18" in the northern and western suburbs in Maryland and Virginia. NWS reported that snow, sleet and rain were still falling and more snow is expected as the back side of the low moves into the region.The New York City region remained under an NWS Winter Storm Warning until 6 a.m. on Friday, February 14 and the National Weather Service expects minor coastal impacts Thursday into Friday afternoon.New England was also being battered by the storm. At 10:56 a.m. EST, Barnstable, Mass. on Cape Cod was experiencing rain and winds gusting to 28 mph. An NWS wind advisory is in effect for Cape Cod until 7 p.m. EST. Further north, Portland, Maine was experiencing heavy snow with winds from the northeast at 6 mph. The National Weather Service in Gray, Maine noted "Significant snowfall is likely for much of western Maine and New Hampshire as this storm passes by. There will be a mix or changeover to sleet and freezing rain over southern and coastal sections tonight...before all areas end as a period of snow Friday (Feb. 14) morning." On February 13 at 10 a.m. EST, NOAA's National Weather Service noted "An abundance of Atlantic moisture getting wrapped into the storm will continue to fuel widespread precipitation...which should lift through the Mid-Atlantic States and Northeast Thursday into Friday. A wide swath of heavy snow accumulations are expected with this storm...but air [moving] off the warmer ocean water should change snow over to rain along the coastal areas. Also...a narrow axis of sleet and freezing rain will be possible within the transition zone...which is expected to set up near the I-95 corridor." For updates on local forecasts, watches and warnings, visit NOAA's www.weather.gov webpage. GOES satellites provide the kind of continuous monitoring necessary for intensive data analysis. Geostationary describes an orbit in which a satellite is always in the same position with respect to the rotating Earth. This allows GOES to hover continuously over one position on Earth's surface, appearing stationary. As a result, GOES provide a constant vigil for the atmospheric "triggers" for severe weather conditions such as tornadoes, flash floods, hail storms and hurricanes.For updated information about the storm system, visit NOAA's WPC website: www.hpc.ncep.noaa.gov/For more information about GOES satellites, visit: www.goes.noaa.gov/ or goes.gsfc.nasa.gov/Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team NASA image use policy.NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission.Follow us on TwitterLike us on FacebookFind us on Instagram" data-credit="NASA Goddard Photo and Video/Flickr">

Os cientistas há muito tempo sabem que a Terra produz um som estranho, - uma espécie de zumbido - de baixa frequência, inaudível para os humanos, mas que pode ser detectado por instrumentos sísmicos.

Porém, os cientistas nunca puderam afirmar com certeza qual é a causa dessa atividade “microssísmica”.

Até agora.

Um novo estudo publicado online em 10 de fevereiro de 2015, na Revista Geophysical Research Letters, indica que esse zumbido é causado, em sua maioria, por ondas do oceano que fazem com que o nosso planeta vibre sutilmente - ou "produza esse som”, segundo os pesquisadores.

“Demos um grande passo ao explicarmos isso”, disse o Dr. Fabrice Ardhuin, um cientista pesquisador sênior no Centro Nacional de Pesquisa Científica em Brest, na França e principal autor do estudo, em uma declaração escrita. “Agora sabemos de onde esse ‘som’ vem e a próxima pergunta é: o que podemos fazer com essa informação?”.

Pegando as grandes culpadas. Com a ajuda de modelos computadorizados do oceano, do vento e do fundo do mar, os cientistas conseguiram identificar exatamente os tipos de ondas que causam esse som e como elas fazem isso, relatou ao site Live Science.

Os pesquisadores descobriram que as colisões das ondas do oceano geram alguma atividade sísmica, mas que era principalmente o movimento e a pressão das ondas gigantes e lentas, que se estendem até o fundo do mar, que causam esse zumbido na Terra.

(O artigo continua após a imagem.)

O gráfico à esquerda mostra a altura das ondas gigantes que podem chegar ao fundo do mar. A imagem à direita mostra esses tipos de ondas durante uma tempestade em uma praia ao sul de Bordeaux, na França. A pressão dessas enormes ondas no fundo do mar gera ondas sísmicas que fazem com que a Terra oscile, segundo os cientistas.

Como o zumbido pode nos ajudar. A atividade microssísmica causada pelas ondas gigantes do oceano penetra profundamente no manto terrestre e, possivelmente, no seu núcleo. Isso sugere que, ao registrá-lo, os cientistas possam obter mais informações sobre o interior do nosso planeta, de acordo com os pesquisadores.

Como seria o zumbido se ele estivesse em uma frequência maior – ao alcance do ouvido humano?

“Se você conseguisse pôr o zumbido a uma velocidade 10.000 vezes maior, você ouviria um ‘ruído branco’ como os emitidos por um aparelho de televisão velho ao mudar de canal,” disse Ardhuin por e-mail ao The Huffington Post.

É. Talvez seja bom não sermos capazes de ouvir esse zumbido.

Tradução: Simone Palma

Este artigo foi originalmente publicado pelo HuffPost US e traduzido do inglês.

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