Figures 13a et 13b. Il est possible de les obtenir dans des quincailleries ordinaires. Choisir une compagnie qui offre une garantie de dix ans sur ses produits. Figures 27a et 27b. Ces produits sont offerts en feuilles ou en rouleaux. Les formes les plus courantes sont de minuscules grains, des arachides en forme de S , des flocons en forme de coquilles et des brins en forme de spaghetti.
Figures 32a et 32b. Il est aussi possible de les acheter dans des dimensions standards. Il est aussi moins transparent et moins fiable. Nylon 6,6 est une pellicule transparente. De plus, le verre est assez rigide plus que les plastiques. Robe de mariage chinoise soutenue par une tige en Plexiglas. Il faut faire preuve de prudence. Suspendre des objets exige des soins particuliers. En pratique, la plupart des pellicules de PTE seront acceptables. Barclay, R. Bergeron et C. Schlichting, Ottawa Ontario , Institut canadien de conservation, Inbuilt options that make your site truly unique without all the load.
Skip to content. Promote your latest design work, photography, artwork, and more with Draft Download Theme. Featured Articles. Sunset Seen from the International Space Station. The image presents an edge-on, or limb view, of the Earth's atmosphere as seen from orbit. The Earth's curvature is visible along the horizon line, or limb, that extends across the image from center left to lower right. Above the darkened surface of the Earth, a brilliant sequence of colors roughly denotes several layers of the atmosphere. A thick river of smoke flowed southeast over New England from several large forest fires in southern Quebec, Canada on May 31, These images show both the fires top image and the thick smoke they produced lower image.
Dense smoke pours from the fires and blows south toward the city of Quebec, a cement gray region along the St. Lawrence River The Worst Petroleum Disasters Ever. Humans have punched hundreds of thousands of holes into the Earth in pursuit of fossil fuels. Most of the time, these wells work as they're supposed to, but as last month's Deepwater Horizon Rig blowout shows, failure can be catastrophic. Here are some of the deadliest, most destructive petroleum disasters in history. Flying through a cloud of volcanic ash poses a significant hazard to airlines.
The fine, glassy particles that make up volcanic ash scour airplane windows and can clog and stall jet engines. So when clouds of volcanic ash drifted south over Europe from Iceland at various times in April and May , many countries grounded all flights During the first weeks following the explosion at the Deepwater Horizon well in the Gulf of Mexico, oil drifting from the site of the incident usually headed west and northwest to the Mississippi River Delta.
But in the third week of May, currents drew some of the oil southeast. According to the National Oceanic and Atmospheric Administration NOAA , the southward spread increased the chance that the oil would become mixed up with the Loop Current, which might carry the oil toward Florida and the Keys Nearly a month after a deadly explosion at the Deepwater Horizon oil rig, the damaged well on the bottom of the Gulf of Mexico continued to spill oil. In the weeks since the accident occurred, the oil slick has periodically drifted northeast toward the Mississippi Delta and reached the the Chandeleur Islands After more than a week of relatively subdued activity in late April, Iceland's Eyjafjallajokull Volcano began a fresh round of explosive ash eruptions in the first week of May.
On the morning of May 6, On April 20, , the oil rig Deepwater Horizon suffered an explosion and sank two days later. Shortly thereafter, oil began leaking into the Gulf of Mexico from ruptured pipes deep on the ocean floor. NASA satellites have been tracking the growth of the oil spill as it has spread towards the northern Gulf Coast A massive oil slick in the Gulf of Mexico continued spreading on April 29, , moving perilously close to shore, according to news reports. The U. Coast Guard attempted controlled burns on some of the oil to prevent its spread, but had to halt the process due to high winds.
Meanwhile, the U. National Oceanic and Atmospheric Administration constructed a dome-and-pipe system to contain the spread of oil at the sea floor. Prominence from the Solar Dynamics Observatory. The mission's high-speed, IMAX-quality photography will improve predictions of solar activity that can disrupt everything from GPS satellites to high-voltage power lines. Arctic Sea Ice Extent, An estimated 42, gallons of oil per day were leaking from an oil well in the Gulf of Mexico in late April, following an explosion at an offshore drilling rig on April 20, The rig eventually capsized and sank Early in the day, seismic tremors hinted that lava might have started flowing from the volcano, said the Icelandic Met Office.
When the Icelandic Coast Guard flew over the volcano at , they observed magma being thrown 1. Lava flows filled gullies and built mounds of frothy rock, and they melted and vaporized the winter snow, creating relatively small steam plumes.
Ash Plume across the North Atlantic. Terra Tracks Earth's Vital Signs. On February 24, , after two months of post-launch testing, sensors on NASA's Terra satellite began opening their shutters and making their first observations. The mission ushered in a decade of observations from NASA's Earth Observing System, a coordinated series of satellites that monitor how Earth is changing Polar Mesospheric Clouds, Southern Hemisphere. This striking astronaut photograph shows polar mesospheric clouds over the Southern Hemisphere on January 30, These clouds occur over the high latitudes of both the Northern and Southern Hemispheres during their respective summer months at very high altitudes approximately 76 to 85 kilometers, or 47 to 53 miles.
They are most visible during twilight, when the clouds are still illuminated by the setting Sun, while the ground is already dark. Coronal Mass Ejection in late January The arcs are plasma, superheated matter made up of moving charged particles electrons and ions Global Change magazine and newsletter archive. IGBP's magazine highlights the high-quality research arising from its core projects and projects that it co-sponsors.
By including articles that draw linkages between science, society and policy, the magazine aspires to serve as a source of information not only to scientists, but also to funding agencies, policymakers, journalists and the general public.
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The annual ozone hole started developing over the South Pole in late August , and by September 10, it appeared that the ozone hole of would be comparable to ozone depletions over the past decade. North Pole Sea Ice Minimum The reach of Arctic sea ice fluctuates through the year, growing in the winter and shrinking through the summer. The new method offers as much as one hour advance warning, giving astronauts time to seek shelter and ground controllers time to safeguard their satellites when a storm is approaching.
Led by NASA Goddard scientist Paul Newman, a team of atmospheric chemists simulated 'what might have been' if chlorofluorocarbons CFCs and similar ozone-depleting chemicals were not banned through the Montreal Protocol. NASA Images. Global Aerosol System If nations hadn't agreed in to ban the chemicals that eat up the Earth's protective ozone layer, the world would have been a much different place later this century, with nearly two-thirds of the ozone layer gone and the ozone hole a permanent fixture over Antarctica, a new simulation shows.
Historical trends in carbon dioxide concentrations and temperature, on a geological and recent time scale. The most recent geological history, in the last hundred thousand years, has been characterised by cycles of glaciations, or ice ages. The historic temperatures, through these times, have been low, and continental ice sheets have covered large parts of the world Earth's ozone layer should eventually recover from the unintended destruction brought on by the use of chlorofluorocarbons CFCs and similar ozone-depleting chemicals in the 20th century.
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But new research by NASA scientists suggests the ozone layer of the future is unlikely to look much like the past because greenhouse gases are changing the dynamics of the atmosphere Antarctic Ozone Hole: to The stratospheric ozone layer protects life on Earth by absorbing ultraviolet light, which damages DNA in plants and animals including humans and leads to skin cancer.
Prior to , scientists had not observed concentrations below Dobson Units.
But in the early s, through a combination of ground-based and satellite measurements, scientists began to realize that Earth's natural sunscreen was thinning dramatically over the South Pole each spring. This large, thin spot in the ozone layer caused by chloroflourocarbons CFCs came to be known as the ozone hole Antarctic Ozone Hole.
This large, thin spot in the ozone layer came to be known as the ozone hole Wilkins Ice Bridge Collapse. The Wilkins Ice Shelf, on the western side of the Antarctic Peninsula, experienced multiple disintegration events in A rapid retreat started in February, near the end of the Antarctic summer Ozone is Earth's natural sunscreen, absorbing most of the incoming ultraviolet UV radiation from the sun and protecting life from DNA-damaging radiation.
Hawaiian Vog Photographed from Space Shuttle. Kilauea Volcano, on the island of Hawaii, has been erupting continuously since Antarctic sea ice grows to its maximum each September and melts to its minimum in late February, after which it resumes growing rapidly.
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This image pair shows monthly Antarctic sea ice concentration for the most recent winter maximum September , left and summer minimum February , right Late in April , astronauts aboard the International Space Station observed a strange circular area of thinned ice in the southern end of Lake Baikal in southern Siberia.
Siberia is remote and cold; ice cover can persist into June. The latest Newsletter of the International Geosphere-Biosphere Programme is now available for download. The summer minimum and the winter maximum are the two pivotal milestones in the annual cycle of Arctic sea ice. The thickness of sea ice and the extent at each of these times are key indicators of Arctic climate. Over the past two and a half decades, the extent of sea ice at the end of summer mid-September has declined significantly.
The corollary to that trend is that at the winter maximum end of February or mid-March , the ice covering the Arctic is much younger and thinner than it was in the past Though greenhouse gases are invariably at the center of discussions about global climate change, new NASA research suggests that much of the atmospheric warming observed in the Arctic since may be due to changes in tiny airborne particles called aerosols Arctic ice shows winter thinning. BBC News - Arctic ice reached a larger maximum area this winter than in the last few years, scientists say, but the long-term trend still shows it declining.
Melting on the Greenland Ice Cap, The northern fringes of Greenland's ice sheet experienced extreme melting in , according to NASA scientist Marco Tedesco and his colleagues. This image shows the number of days when melting occurred on the ice sheet compared to the average number of melt days between and Calendar year was the coolest year since , according to the NASA Goddard Institute for Space Studies GISS analysis of worldwide temperature measurements, but it was still in the top ten warmest years since the start of record-keeping in Given the range of uncertainty in the measurements, the GISS team concluded that was somewhere between the seventh and the tenth warmest year on record.
The 10 warmest years have all occurred within the year period from Water vapor is known to be Earth's most abundant greenhouse gas, but the extent of its contribution to global warming has been debated. Using recent NASA satellite data, researchers have estimated more precisely than ever the heat-trapping effect of water in the air, validating the role of the gas as a critical component of climate change. Following a record-breaking season of arctic sea ice decline in , NASA scientists have kept a close watch on the melt season.
Although the melt season did not break the record for ice loss, NASA data are showing that for a four-week period in August , sea ice melted faster during that period than ever before. Grande conjonction. Sky-event alert: Venus joins Jupiter after sunset This Thanksgiving weekend, the sky's two brightest planets stand poised to pass each other in evening twilight. A slim crescent Moon will join the pair December 1.
New Sunspot Cycle Begins. Activity on our Sun varies over a roughly year cycle. At the beginning of a cycle, sunspots are sparse. The spots gradually increase over several years, peak, and subsequently decrease over the next several years, with spots from old and new cycles often occurring simultaneously as a new cycle starts.
From to , astronomers counted a total of 23 cycles of sunspot activity. In January , satellite imagery showed the beginnings of Solar Cycle Sunspot activity remained minimal in the months that followed, but at the end of October , another batch of sunspots appeared, most of them belonging to the new cycle. Melt Ponds, Northeastern Greenland. Glaciologists have long been fascinated with the complex terrain of ice sheets, massive bodies of land-based ice in Greenland and Antarctica. Fires increase surface ozone. You don't have to be nearby to know when wildfires burn through remote forests in the U.
Even far from the fire, the Sun turns orange as its light reaches through a brown-tinted sky, and a faint hint of smoke flavors the air. It's no surprise that the choking smoke is a health hazard up close, but it may pose a risk to those farther away who see little or no smoke. A recent study conducted at the National Center for Atmospheric Research found that distant wildfires can raise ground-level ozone concentrations to unhealthy levels even at large distances from the fire location Un petite page d'humour The Ozone Hole of On September 12, , the Antarctic ozone hole reached its maximum size for the year.
Represented by blues and purples in this image from the Ozone Monitoring Instrument OMI on NASA's Aura satellite, the ozone hole covered about 27 million square kilometers, making it larger than North America, which is about 25 million square kilometers. Though larger than it was in , the ozone hole was still smaller than the record set in The arrival of Northern Hemisphere autumn signals the end of the seasonal retreat of Arctic sea ice.
Polar scientists from the National Snow and Ice Data Center report that sea ice appeared to hit its lowest extent on September 14, , when the area at least 15 percent covered by ice dropped to 4. The minimum is the second-lowest recorded since , or 2. Chimie verte - La chimie verte est loin de colorer l'industrie. Pour monsieur et madame Tout-le-monde, cette industrie rime avec pollution. As of the first week of September , Arctic sea ice extent had not fallen below the record low observed in , but the season set a new kind of record.
Solar Superstorm. Any disaster capable of causing large-scale blackouts, disrupting communications networks, and damaging satellites is something to prepare for. These are just a few of the effects that follow powerful eruptions from the Sun. Scientists now recognize that we haven't seen the worst the Sun can throw at us. Solar flares in kicked off a storm so massive that, if it happened today, could cripple much of the technology we've come to rely on. Timeline: The Frightening Future of Earth.
Our planet's prospects for environmental stability are bleaker than ever with the approach of this year's Earth Day, April Global warming is widely accepted as a reality by scientists and even by previously doubtful government and industrial leaders. And according to a recent report by the Intergovernmental Panel on Climate Change IPCC , there is a 90 percent likelihood that humans are contributing to the change.
Two Evils Compete: Global Warming vs. Ozone Hole. The evils of global warming and ozone depletion are competing problems, at least in Antarctica, the results of two new studies suggest. Vast cracks appear in Arctic ice. Dramatic evidence of the break-up of the Arctic ice-cap has emerged from research during an expedition by the Canadian military. Jour de la Terre.
Signs of Summer Thaw on the Antarctic Peninsula. The tip of the Antarctic Peninsula showed dramatic seasonal changes in late January Several days later, on January 30, , the ice's new blue hue suggested something had changed Global Temperature Anomalies: Nevertheless, global average surface temperature in was still tied for the second warmest year in the instrumental record compiled by scientists at NASA's Goddard Institute for Space Studies, which goes back to The global average temperature anomaly for was 0.
Retreat of the Tasman Glacier. NIWA scientists attributed the glacial retreat primarily to global warming and stated that, in the absence of substantial climate cooling, 12 of the largest glaciers would not recover to their previous sizes. Changing Climate - National Geographic Magazine. Surface temperatures on Earth are warming at a pace that signals a decisive shift in the global climate. Click through this map to see how climate change is affecting the planet. The Dawn of a New Solar Cycle.