یادداشت های یک زمین شناس Diary of a geologist

نا آرامی و آشوب در در آتشفشان " توری آلبا " ، " کا ستاریکا " Unrest at Turrialba Volcano, Costa Rica

2012-01-29T09:06:00.000+03:30

Turrialba Volcano, located in central Costa Rica, emits a translucent plume of volcanic gases in this natural-color satellite image from January 21, 2010. According to the RED Sismológica Nacional (Costa Rican National Seismological Network), activity at the volcano increased markedly on January 4, 2010. Strong, long-lasting volcanic tremors were accompanied by gas plumes over the volcano, and emissions of ash began on January 5th. The “jet-type noise” of gas and ash rushing out of fumaroles was heard several kilometers away. On January 21, Nacion.comreported that potato and carrot farmers were asked to leave fields near the volcano’s summit due to further increases in gas emissions.

The barren summit region of the 3,340-meter- (10,960-foot-) high Turrialba appears gray and brown, while the volcanic plume is a hazy blue. Fields and pastures are light green, in contrast to dark green forest that covers the high-elevation ridges. Since 2007, frequent acid rain showers caused by activity at the volcano killed or damaged much of the vegetation to the southwest of the summit, leaving the area brown and orange. This image was acquired by the Advanced Land Imager (ALI) aboard NASA’s Earth Observing-1 (EO-1) satellite.

1. Reference

2. Nacion.com. (2010, January 21). Suspendida agricultura cerca del volcán Turrialba. Accessed January 25, 2010.

3. Red Sismológica Nacional. (2010, January). Turrialba Volcano, Costa Rica. Current Activity: January 4-10, 2010. Preliminary Report. Accessed January 25, 2010.

4. Volcano Live. (2010, January). Turrialba Volcano - John Search. Accessed January 25, 2010.

پسروی یخچال ها ی قطبی Retreating Glaciers

2012-01-29T09:01:00.000+03:30

Satellite image of the Jakobshavn Glacier, Greenland's largest and fastest moving tidewater glacier, which is retreating under conditions similar to those Briner studied in the Canadian Arctic. NASA Landsat Geocover image.

Study shows that Ice Sheets Can Retreat in a Geologic Instant

Glaciers Are Capable of Rapid Retreat

Modern glaciers, such as those making up the Greenland and Antarctic ice sheets, are capable of undergoing periods of rapid shrinkage or retreat, according to new findings by paleoclimatologists at the University at Buffalo.

The paper, published on June 21 in Nature Geoscience, describes fieldwork demonstrating that a prehistoric glacier in the Canadian Arctic rapidly retreated in just a few hundred years.

The proof of such rapid retreat of ice sheets provides one of the few explicit confirmations that this phenomenon occurs.

Should the same conditions recur today, which the UB scientists say is very possible, they would result in sharply rising global sea levels, which would threaten coastal populations.

استانبول ، ترکیه Istanbul, Turkey

2012-01-29T08:55:00.000+03:30

The population of Turkey's economic and cultural center has exploded in recent decades.

The rise and fall of empires is easy to read in Istanbul’s richly varied architecture. Stately 19th century wood townhouses are tucked in the shadow of the fifteenth century Ottoman palace. The late Roman or early Byzantineaqueduct of Constantinople cuts across the city center, a straight line across a skyline punctuated with minarets on mosques that are only centuries old. But as much as history has left its imprint on Istanbul’s make-up, modern civilization may have a far greater impact on its shape.

Istanbul has grown by more than 11 million people in the last 50 years, and the city has expanded to accommodate its new population. This pair of images contrasts Istanbul’s size in 1975 to its size in 2011. Both images come from the Landsat series of satellites and show the city in false color. Plant-covered land is red, while urban areas are gray. Lightly vegetated land or bare earth is tan, and water is black.

In 1975, Istanbul was still centered around the Golden Horn, the estuary that flows southwest into the Bosporus Strait. By 2011, the city had expanded over many kilometers to the east and west, and a new reservoir is visible to the west. Istanbul housed more than 13 million people by the end of 2011—18 percent of the population of Turkey. Much of Istanbul’s growth is happening as people move to the city for industrial jobs.

The images reveal some interesting patterns of growth. In 1973, the first bridge across the Bosporus opened, connecting the Asian side of Istanbul to the European side. The bridge is faintly visible in the 1975 image, and the urban areas in the newly connected east are near the bridge. In 1988, Istanbul opened a second bridge across the Bosporus. Farther north, this bridge is visible in the 2011 image. Not surprisingly, the dark gray of dense settlement has filled in the area between the two bridges on both sides of the strait.

This modern sprawl may be nothing new for Istanbul. Archeologists recently identified a wealthy port city some 13 miles west of Istanbul that was operating during the fourth to sixth centuries, during the founding of Constantinople. Though the find is new and not well understood, the city may have acted as a satellite harbor and retreat for the wealthy of Constantinople. The city appeared to have been abandoned after an earthquake flattened it in 1037.

1. References

2. Finkel, A. (2011, November 16). The bridge to nowhere. International Herald Tribune. Accessed January 27, 2012.

3. Istanbul Metropolitan Municipality. (2008). Population and demographic structure. Accessed January 27, 2012.

4. Pinkowski, J. (2012, January 23). After being stricken by drought, Istanbul yields ancient treasure. New York Times.Accessed January 27, 2012.

5. Republic of Turkey Turkish Statistical Institute. (2012, January 27). The results of address based population registration system. Accessed January 27, 2012.

انفجار جمعیت در دهه ی اخیر ناشی از شرایط اقتصادی و فرهنگی در استانبول

فعالیت زبانه های خورشید The Sun Flares with Activity

2012-01-28T06:48:00.000+03:30

Following one of the longest and weakest periods of activity in many cycles, the Sun is brimming with activity again. In late January 2012, our nearest star offered a preview of what may be to come in the solar maximum of 2012–13. The storm has the potential to disrupt some communications and satellite systems and to bring auroras to high-latitude skies.

The images above show a solar flare as observed by the Atmospheric Imaging Assembly (AIA) on NASA’s Solar Dynamics Observatory (SDO) at 03:27, 03:42, and 04:12 Universal Time (Greenwich Time) on January 23. Note the brightening of the solar surface as gas was superheated and magnetically supercharged. By the third (right) image, a stream of solar material is seen flowing off into space above the hot spot, likely solar protons and a coronal mass ejection. Click on the enlarged images and movies for a wider view.

The high-latitude solar flare was measured as M8.7 in intensity, just below the most intense “X class” of flares. The eruption sent a stream of fast-moving, highly energetic protons toward Earth, provoking the most intense solar energetic particle storm—an S3 on NOAA Space Weather Prediction Center’s scale—since 2005.

The flare was accompanied by a coronal mass ejection (CME), a cloud of solar plasma that was ejected from the solar atmosphere in the direction of Earth. The CME was observed by the STEREO and SOHO spacecraft with an initial speed of more than 2,000 kilometers (1,400 miles) per second. It was estimated to reach Earth sometime on January 24 and Mars on January 25. NOAA forecasters were predicting a G2 geomagnetic storm, though a G3 was possible.

Solar flares and CMEs are not a danger to humans on Earth's surface, as the planet's magnetic field (magnetosphere) and atmosphere deflect and absorb the solar energy and particles. The sun storms can pose some risks to astronauts, and they can upset the electronics and transmissions on science, military, and communications satellites. Closer to Earth's surface, solar activity can cause disruptions of radio signals (particularly HF), provide a small dose of radiation to passengers on high-latitude flights, and provoke auroras (northern and southern lights).

The storm is impressive by recent standards, but nowhere near the maximum intensities often generated at the height of the solar cycle. “I would expect that we will see more storms like this one or even bigger as we get closer to solar maximum,” said Michael Hesse, chief of heliophysics at NASA’s Goddard Space Flight Center.

در یکی ار دوره های فراز و فرود زبانه های خورشید هستیم که بار دیگرجنبایی از سر گرفته است . در اواخر ژانویه ی 2012 ، نزدیکترین ستاره بما ، بیان از حداکثرفعالیت های خورشید دارد . در سال های 2012 -2013 توفان سبب اختلالات در ارتباطات و ماهواره ها و ایجاد ریز گرد ها در آسمان عرض های بالایی خواهد شد .

آتش و یخ در آتشفشا ن ِ " کی زی من" Fire and Ice at Kizimen Volcano

2012-01-21T09:52:00.000+03:30

The low-in-the-sky winter sun casts extraordinarily long shadows in this satellite image of Russia’s Kizimen Volcano. A light-colored plume, likely steam-rich, rises above Kizimen’s summit, while a growing lava flow (mostly hidden by gases) descends the eastern flank. Emissions of ash, lava, and volcanic gases have been nearly continuous since the eruption started in November 2010.

This false-color image was acquired on January 11, 2012, by the Advanced Spaceborne Thermal Emission and Reflection Radiometer aboard the Terra satellite. Snow covers the landscape at high altitudes, and the evergreen forests to the north of the volcano are dark red-brown. The light brown hills nearby are covered with leafless deciduous trees poking above the snow.

1. Reference

2. Kamchatka Volcanic Eruption Response Team. (2012, January 12). KVERT Information Releases. Accessed January 13, 2012.

تولد جزیره ای آتشفشانی در دریای سرخ A Newborn Volcanic Island in the Red Sea

2012-01-20T06:22:00.000+03:30

A volcanic eruption in the Red Sea appears to have stopped, leaving behind a newborn island. The new island is part of the Zubair Islands, located about 60 kilometers (40 miles) off the coast of Yemen. The Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite acquired this natural-color image on January 15, 2011.

1. References

2. Gass, I.G., Mallick, D.I.J., Cox, K.G. (1973). Volcanic islands of the Red Sea. Journal of the Geological Society, 129(3), 275–309.

3. Klemetti, E. (2011, December 19). Potential eruption off the coast of Yemen. Eruptions. Accessed December 27, 2011.

دلتای رودخانه ی زرد Yellow River Delta

2012-01-19T06:48:00.000+03:30

China’s Huang He (Yellow River) is the most sediment-filled river on Earth. Flowing northeast to the Bo Hai Sea from the Bayan Har Mountains, the Yellow River crosses a plateau blanketed with up to 300 meters (980 feet) of fine, wind-blown soil. The soil is easily eroded, and millions of tons of it are carried away by the river every year. Some of it reaches the river’s mouth, where it builds and rebuilds the delta.

The Yellow River Delta has wandered up and down several hundred kilometers of coastline over the past two thousand years. Since the mid-nineteenth century, however, the lower reaches of the river and the delta have been extensively engineered to control flooding and to protect coastal development. This sequence of natural-color images from NASA's Landsat satellites shows the delta near the present river mouth at five-year intervals from 1989 to 2009.

Between 1989 and 1995, the delta became longer and narrower along a southeast-bending arc. In 1996, however, Chinese engineers blocked the main channel and forced the river to veer northeast. By 1999, erosion and settling along the old channel caused the tip of the delta to retreat, while a new peninsula had formed to the north.

The new peninsula thickened in the next five-year interval, and what appears to be aquaculture (dark-colored rectangles) expanded significantly in areas south of the river as of 2004. By 2009, the shoreline northwest of the new river mouth had filled in considerably. This may be the outcome that the engineers were anxious to achieve: the land northwest of the newly fortified shoreline is home to an extensive field of oil and gas wells. Their protection is a primary concern.

Although levees, jetties, and seawalls allow officials to slow erosion and direct the

flow of the river, other challenges to protecting the delta’s natural wetlands and its agricultural and industrial development remain. Water and sediment flows to the delta have declined dramatically since the 1970s, due to both reduced rainfall and explosive urban and agricultural demand for water upstream. In the 1990s, the river frequently ran dry well before reaching the delta.

These low- and no-flow periods are a huge problem in the lower reaches of the river and the delta. They severely damage wetlands and aquaculture and worsen the river’s already severe water pollution problem. Ironically, they also increase the flood risk because when flows are low, sediment fills in the riverbed. The river becomes shallower and higher in elevation. In places, the river is already perched above the surrounding floodplain by as much as 10 meters (30 feet). A levee breach during a high water event could be devastating.

1. References

2. Baosheng, W., Zhaoyin, W., and Changzhi, Li. (2004). Yellow River Basin management and current issues. Journal of Geographical Sciences, 14, supplement, 29-37.

3. Chu, Z., Sun, X., Zhai, S., and Xu, K. (2006). Changing pattern of accretion/erosion of the modern Yellow River (Huanghe) subaerial delta, China: Based on remote sensing images. Marine Geology,227, 13-30.

4. Li, S., Wang, G., Deng, W., Hu, Y., and Hu, W. (2009). Influence of hydrology process on wetland landscape pattern: A case study in the Yellow River Delta.Ecological Engineering, 35, 1719-1726.

5. Liu, J.P., Milliman, J., Gao, S., and Cheng, P. (2004). Holocene development of the Yellow River’s subaqueous delta, North Yellow Sea. Marine Geology, 209, 45-67.

6. Xue, C. (1993). Historical changes in the Yellow River delta, China. Marine Geology,113, 321-329.

شهر نشینی " دوبی " . تبدیل به شهر شدن ِ " دبی" Urbanization of Dubai

2012-01-19T06:42:00.000+03:30

Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite observed its progress from 2000 to 2011.

In these false-color images, bare ground appears brown, vegetation appears red, water appears dark blue, and buildings and paved surfaces appear light blue or gray. The first image, acquired in November of 2000, shows the area prior to the island’s construction. The image from February 2002, shows the barest beginnings of the artificial archipelago. By October 2002, substantial progress had been made on Palm Jumeirah, with many sandy “palm fronds” inside a circular breakwater.

By November 2003, the palm tree has been constructed, and buildings and vegetation populate Palm Jumeirah in the images from November 2004, October 2005, September 2006, March 2007, and November 2008. The final image, acquired in February 2011, shows vegetation on most of the palm fronds, and numerous buildings on the tree trunk.

Inland, changes are just as dramatic between November 2000 and February 2011. In the earliest image, empty desert fills the lower right quadrant of the image, as cityscape primarily hugs the coast. As the years pass, urbanization spreads, and the final image shows the area almost entirely filled by roads, buildings, and irrigated land.

· References

· Earth Observatory. (2006, October 22). Palm Islands, Dubai. Accessed April 23, 2009.

· Van Oord. The Making of: Palm Jumeirah, Dubai. Accessed April 23, 2009.

· Wikipedia. (2009, April 18). Palm Islands. Accessed April 23

جنگل تراشی ِ " آمازون" Amazon Deforestation

2012-01-19T06:31:00.000+03:30

The state of Rondônia in western Brazil — once home to 208,000 square kilometers of forest (about 51.4 million acres), an area slightly smaller than the state of Kansas — has become one of the most deforested parts of the Amazon. In the past three decades, clearing and degradation of the state’s forests have been rapid: 4,200 square kilometers cleared by 1978; 30,000 by 1988; and 53,300 by 1998. By 2003, an estimated 67,764 square kilometers of rainforest—an area larger than the state of West Virginia—had been cleared.

By the start of this satellite time series from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, the frontier had reached the remote northwest corner of Rondônia. Intact forest is deep green, while cleared areas are tan (bare ground) or light green (crops, pasture, or occasionally, second-growth forest). Over the span of eight years, roads and clearings pushed west-northwest from Buritis toward the Jaciparaná River. The deforested area along the road into Nova Mamoré expanded north-northeast all the way to the BR-346 highway.

Deforestation follows a fairly predictable pattern in these images. The first clearings that appear in the forest are in a fishbone pattern, arrayed along the edges of roads. Over time, the fishbones collapse into a mixture of forest remnants, cleared areas, and settlements. This pattern follows one of the most common deforestation trajectories in the Amazon. Legal and illegal roads penetrate a remote part of the forest, and small farmers migrate to the area. They claim land along the road and clear some of it for crops. Within a few years, heavy rains and erosion deplete the soil, and crop yields fall. Farmers then convert the degraded land to cattle pasture, and clear more forest for crops. Eventually the small land holders, having cleared much of their land, sell it or abandon it to large cattle holders, who consolidate the plots into large areas of pasture.

کهکشا ن Highest Rated Universe

2012-01-19T06:17:00.000+03:30

کهکشان ما حد اقل 100 میلیارد سیاره دارد Our Galaxy Has at Least 100 Billion Planets

2012-01-18T07:44:00.000+03:30

This artist's illustration gives an impression of how common planets are around the stars in the Milky Way galaxy. The planets, their orbits, and their host stars are all vastly magnified compared to their real separations. A six- year search that surveyed millions of stars using the microlensing technique concluded that planets around stars are the rule rather than the exception. The average number of planets per star is greater than one. Image credit: NASA/ESA/ESO

Study Shows Our Galaxy Has at Least 100 Billion Planets

January 11, 2012

Our Milky Way galaxy contains a minimum of 100 billion planets, according to a detailed statistical study based on the detection of three planets located outside our solar system, called exoplanets.

The discovery, to be reported in the January 12 issue of Nature, was made by an international team of astronomers, including co-author Stephen Kane of NASA's Exoplanet Science Institute at the California Institute of Technology in Pasadena, Calif.

The survey results show that our galaxy contains, on average, a minimum of one planet for every star. This means that it's likely there are a minimum of 1,500 planets within just 50 light-years of Earth.

The study is based on observations taken over six years by the PLANET (Probing Lensing Anomalies NETwork) collaboration, using a technique called microlensing to survey the galaxy for planets. In this technique, one star acts like a magnifying lens to brighten the light from a background star. If planets are orbiting the foreground star, the background star's light will further brighten, revealing the presence of a planet that is otherwise too faint to be seen.

The study also concludes that there are far more Earth-sized planets than bloated Jupiter-sized worlds. A rough estimate from this survey would point to the existence of more than 10 billion terrestrial planets across our galaxy.

"Results from the three main techniques of planet detection, including microlensing, are rapidly converging to a common result: Not only are planets common in the galaxy, but there are more small planets than large ones," said Stephen Kane, a co-author from NASA's Exoplanet Science Institute at Caltech. "This is encouraging news for investigations into habitable planets."

Read the full story at http://hubblesite.org/newscenter/archive/releases/2012/07 .

NASA's Exoplanet Science Institute at Caltech is the science operations and analysis center for NASA's Exoplanet Exploration Program, managed by the Jet Propulsion Laboratory, Pasadena, Calif., for NASA. More information is at http://nexsci.caltech.edu and http://planetquest.jpl.nasa.gov .

سیستم سیارات - تجسمی هنری - Mini Planetary System (Artist Concept)

2012-01-18T07:40:00.000+03:30

This artist's concept depicts an itsy bitsy planetary system -- so compact, in fact, that it's more like Jupiter and its moons than a star and its planets. Astronomers using data from NASA's Kepler mission and ground-based telescopes recently confirmed that the system, called KOI-961, hosts the three smallest exoplanets known so far to orbit a star other than our sun. An exoplanet is a planet that resides outside of our solar system.

The star, which is located about 130 light-years away in the Cygnus constellation, is what's called a red dwarf. It's one-sixth the size of the sun, or just 70 percent bigger than Jupiter. The star is also cooler than our sun, and gives off more red light than yellow.

The smallest of the three planets, called KOI-961.03, is actually located the farthest from the star, and is pictured in the foreground. This planet is about the same size as Mars, with a radius only 0.57 times that of Earth. The next planet to the upper right is KOI-961.01, which is 0.78 times the radius of Earth. The planet closest to the star is KOI-961.02, with a radius 0.73 times the Earth's.

All three planets whip around the star in less than two days, with the closest planet taking less than half a day. Their close proximity to the star also means they are scorching hot, with temperatures ranging from 350 to 836 degrees Fahrenheit (176 to 447 degrees Celsius). The star's habitable zone, or the region where liquid water could exist, is located far beyond the planets.

The ground-based observations contributing to these discoveries were made with the Palomar Observatory, near San Diego, Calif., and the W.M. Keck Observatory atop Mauna Kea in Hawaii.

NASA's Ames Research Center in Moffett Field, Calif., manages Kepler's ground system development, mission operations and science data analysis. JPL managed the Kepler mission's development.

پیش از ستاره شدن Before They Were Stars: New Image Shows Space Nursery

2012-01-18T07:30:00.000+03:30

A bubbling cauldron of star birth is highlighted in this new image from NASA's Spitzer Space Telescope. Image credit: NASA/JPL-Caltech/Harvard-Smithsonia CfA

January 10, 2012

PASADENA, Calif. -- The stars we see today weren't always as serene as they appear, floating alone in the dark of night. Most stars, likely including our own sun, grew up in cosmic turmoil, as illustrated in this new image from NASA's Spitzer Space Telescope.

The image shows one of the most active and turbulent regions of star birth in our Milky Way galaxy, a region called Cygnus X. The choppy cloud of gas and dust lies 4,500 light-years away in the constellation Cygnus or the "Swan." It is home to thousands of massive stars and many more stars around the size of our sun or smaller. Spitzer has captured an infrared view of the entire region, bubbling with star formation.

"Spitzer captured the range of activities happening in this violent cloud of stellar birth," said Joseph Hora of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who presented the results today at the 219th meeting of the American Astronomical Society in Austin, Texas. "We see bubbles carved out by massive

Most stars are thought to form in huge star-forming regions like Cygnus X. Over time, the stars dissipate and migrate away from each other. It's possible that our sun was once packed tightly together with other, more massive stars in a similarly chaotic, though less extreme, region.

The turbulent star-forming clouds are marked with bubbles, or cavities, carved out by radiation and winds from the most massive of stars. Those massive stars tear the cloud material to shreds, terminating the formation of some stars while triggering the birth of others.

"One of the questions we want to answer is how such a violent process can lead to both the death and birth of new stars," said Sean Carey, a team member from NASA's Spitzer Science Center at the California Institute of Technology, Pasadena, Calif. "We still don't know exactly how stars form in such disruptive environments."

Infrared data from Spitzer is helping to answer questions like these by giving astronomers a window into the dustier parts of the complex. Infrared light travels through dust, whereas visible light is blocked. For example, embryonic stars blanketed by dust pop out in the Spitzer observations. In some cases, the young stars are embedded in finger-shaped pillars of dust that line the hollowed out cavities and point toward the central, massive stars. In other cases, these stars can be seen lining very dark, snake-like filaments of thick dust.

Another question scientists hope to answer is how these pillars and filaments are related.

"We have evidence that the massive stars are triggering the birth of new ones in the dark filaments, in addition to the pillars, but we still have more work to do," said Hora.

Infrared light in this image has been color-coded according to wavelength. Light of 3.6 microns is blue, 4.5-micron light is blue-green, 8.0-micron light is green, and 24-micron light is red. These data were taken before the Spitzer mission ran out of its coolant in 2009, and began its "warm" mission.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/and http://www.nasa.gov/spitzer .

یخ در " گرین لند " در حال تیره شدن است Greenland’s Ice Is Growing Darker

2012-01-10T21:44:00.000+03:30

n the past, the bright surface of the Greenland Ice Sheet reflected well over half of the sunlight that fell on it. This reflectiveness helped keep the ice sheet stable, as less absorbed sunlight meant less heating and melting. In the past decade, however, satellites have observed a decrease in Greenland’s reflectiveness. This darker surface now absorbs more sunlight, which accelerates melting.

The map above shows the difference between the amount of sunlight Greenland reflected in the summer of 2011 versus the average percent it reflected between 2000 to 2006. Virtually the entire ice sheet shows some change, with some areas reflecting close to 20 percent less light than a decade ago. The map is based on observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA’s Terra and Aqua satellites. It was produced as part of the National Oceanic and Atmospheric Administration’s Arctic Report Card.

Climate scientists have long expected that Earth’s polar regions will become less reflective as global temperatures rise. Rising temperatures melt snow and ice, and the uncovered terrain—water, vegetation, bare ground—is darker and absorbs more sunlight. The loss of reflectiveness then amplifies the initial warming.

Most of the patterns on the map fit expectations. Warmer, lower-elevation areas of the ice sheet have darkened more than the colder, higher-altitude interior. Each summer, winter snow retreats from the edge of the ice sheet. Dark pools of melt water form on the surface of the ice, and windblown dust and other particles also collect near the surface, making it even less reflective.

But the darkening in the interior is just as remarkable as the changes at the margins, according to Jason Box of Ohio State University, who analyzed the reflectiveness data. The interior is the high point of the ice sheet, nearly two miles above sea level, and there is no visible melting in the summer. So why is the area becoming darker?

The darkening, says Box, is due to changes in the shape and size of the ice crystals in the snowpack. As temperatures rise, snow grains clump together and reflect less light than the many-faceted, smaller crystals (see lower image from a scanning electron microscope). Additional heat rounds the sharp edges of the crystals, and round particles absorb more sunlight than jagged ones.

1. References

2. NOAA ClimateWatch Magazine (2011, December 1) Highlights of the 2011 Arctic Report Card. Accessed January 9, 2011.

3. NOAA (2011) Arctic Report Card: Update for 2011. Accessed January 9, 2011.

Map by NOAA’s climate.gov team, based on NASA satellite data processed by Jason Box, Byrd Polar Research Center, the Ohio State University. Scanning electron microscope photos courtesy the Electron and Confocal Microscopy Laboratory, USDA Agricultural Research Service. Caption adapted from a story by Rebecca Lindsey, NOAA ClimateWatch.

Instrument:

Terra - MODIS

گرد با د – دیو باد - Tornadoes

2012-01-07T17:54:00.000+03:30

Photograph by Carsten Peter, National Geographic

Tornadoes can be devastating, potent reminders of the awesome power of nature.

In this photo, a rare "mother ship" cloud formation is seen over Childress,Texas. This is a sign of a supercell thunderstorm, a type of storm that often kicks off tornadoes with winds exceeding 200 miles an hour (322 kilometers an hour).

Tornadoes can form over wide swaths of land and sea.

جریان یافتن گدازه در کوه آتشفشا ن " نابرو " در اریتره Lava Flows at Nabro Volcano, Eritrea

2012-01-07T17:42:00.000+03:30

Since the beginning of the recent eruption, a dense plume of water vapor, gas, and ash has concealed the summit of the Nabro volcano. New images from June 29 finally provided a nearly unimpeded view of the summit, where lava flowed out of the erupting vent and down the slope of the volcano.

Located in the East African nation of Eritrea, Nabro began its eruption explosively on June 12, 2011. The powerful eruption sent plumes of ash streaming over North Africa and the Middle East, and pumped vast quantities of sulfur dioxide into the atmosphere. The ash halted flights in East Africa for a time. The eruption killed seven people, said the Eritrean government, and other reports indicate that thousands were affected in both Eritrea and Ethiopia, though news from the region is sparse.

More recently, the volcano has eased into a quieter, lava-oozing phase, as shown in these images from the Advanced Land Imager (ALI) on the Earth Observing-1 (EO-1) satellite. The top image shows the volcano in visible and infrared light (shortwave infrared, near infrared, and green). The hot lava glows orange-red, fading to black as it cools. The long flow on the west side of the volcano is mottled with black, a sign that the surface is cooling. The lava to the east and south of the vent appears to be newer, since little of it has cooled. It is possible that the cooling lava in the western flow diverted the fresh lava to the south and east.

The lower image provides a natural color view of the volcano. A small, slightly brown plume rises from the vent, and ash blackens the ground to the west and south.

Throughout the eruption, satellite images have been nearly the only source of new information about activity at the volcano. Detailed images like this one provide insight into how erupting lava is behaving. For example, volcanologistErik Klemetti used previous images from ALI to estimate how quickly the lava is moving and to guess at how thick (viscous) the lava is.

The Nabro volcano has not erupted in recorded human history, but lava flows near the volcano are relatively recent geologically. Nabro is part of the very active East African Rift, where three tectonic plates are pulling away from each other. As the Earth’s crust thins in the region, volcanoes rise in weak spots.

1. References

2. BBC News. (2011, June 15). Eritrea volcano: Ash disrupts air travel in East Africa. Accessed June 30, 2011.

3. BBC News. (2011, June 20). Eitrea volcano ash hits Ethiopia villages. Accessed June 30, 2011.

4. Eruptions. (2011, June 29). Nabro. Accessed June 30, 2011.

5. Global Volcanism Program. (2011, June 28). Nabro weekly reports. Smithsonian and U.S. Geological Survey. Accessed June 30, 2011.

6. Sudan Tribune. (2011, June 23). Eritrean opposition asks for international support as volcano kills seven. Accessed June 30, 2011.

فعال شد ن آتشفشا ن " کی زی من " Activity at Kizimen Volcano

2012-01-07T17:36:00.000+03:30

On December 30, 2011, Kizimen Volcano emitted a steam plume that condensed rapidly in the frigid winter air of Russia’s Kamchatka Peninsula. Kizimen has been erupting since November 2010, when a fissure opened on the volcano’s southeast flank.

In January 2011, a thick lava flow began to descend from the summit towards the east. This flow is still active, and heat sources along the margins of the flow are visible in infrared imagery. Much of the top of the flow is cool enough to allow snow to accumulate on the surface. As the flow grows, volcanic material spills into a stream valley north of the volcano, covering the valley floor with dark debris.

This natural-color image was acquired by the Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite. White snow covers most of the landscape, with a dusting of brown ash downwind (southeast) of Kizimen’s summit. To the northeast, a fumarole emits a white gas plume. North-facing slopes in the region are in deep shadow because the Sun is low on the horizon in early winter.

1. References

2. Global Volcanism Program. (2011, January). Powerful fissure eruption in November 2010 ends ~82-year repose.Accessed January 3, 2012.

3. Kamchatka Volcanic Eruption Response Team. (2011, December 29). KVERT Information Releases. Accessed January 3, 2012.

جریان گدازه در نزدیکی آتشفشا ن " نیاموراجیرا " Lava Flow near Nyamuragira Volcano

2012-01-07T17:08:00.000+03:30

After bursting to life with 300-meter (1,000-foot) tall lava fountains in November 2011, the eruption of central Africa’s Nyamuragira Volcano continued into the new year.

These satellite images show the volcano on the morning of January 3, 2012. In the natural-color image (top), an active lava flow snakes to the northeast, while the central vent and a volcanic plume rich in sulfur dioxide are also visible. According to volcanologist Erik Klemetti of the Eruptions blog, the orange color and narrow trace of the flow suggest that it is open to the air, unlike flows on Kilauea which are usually carried through lava tubes. Older flows and undisturbed forest are also visible.

The false-color image (lower) shows the summit of Nyamuragira and nearby Nyiragongo Volcano. The heat of the active lava flow causes it to glow in shortwave and near-infrared light, giving a bright red-orange appearance. A lava lake within the summit crater of Nyiragongo is also glowing.

These images were acquired by the Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite.

1. References

2. GORISK. (2011, December 7). November 2011 Eruption. Accessed January 4, 2011.

3. Klemetti, Erik. (2011, November 7). New Fissure Eruption at the Congo’s Nyamuragira. Accessed January 4, 2011.

4. Virunga National Park. (2011, December 6). Last week in Virunga: 28 Nov–4 Dec 2011. Accessed January 4, 2011.

5. Virunga National Park. (2011, November 7). Nyamulagira Volcano Erupts! Accessed January 4, 2011.

1. Related Reading

2. Nyamuragira: Index of Monthly Reports. Global Volcanism Program.

3. Observing Volcanoes, Satellite Thinks for Itself. NASA Earth Observatory.

آذرخش : Photo Gallery: Cloud-to-Ground Lightning

2012-01-05T17:18:00.000+03:30

آذرخش :

Photo Gallery: Cloud-to-Ground Lightning

Circle of Lightning

Photograph by Lynda Smith, My Shot

Lightning forks and rejoins itself over Table Mountain and Lion's Head in Cape Town, South Africa. Central Africa is the area of the world where lightning strikes most frequently.

Grand Canyon, Arizona

Photograph by Michael Nichols, National Geographic

A dramatic cloudburst releases jagged bolts of lightning deep into the Grand Canyon near Point Sublime.

Lightning Over Las Cruces

Photograph by Lionel Brown, Getty Images

Two large lightning bolts strike the ground near Las Cruces, New Mexico. Though human eyes perceive the opposite, lightning moves from the ground up to the cloud.

City Strike

Photograph by Mavroudakis Fotis, My Shot

Lightning strikes Kavala, Greece. The ancient Greek god Zeus was said to control lightning, but today we know lightning comes from a difference in electrical charge between clouds and the ground or among clouds.

Oriental Pearl Lightning Strike

Photograph by Sung Ming Whang, My Shot

A bolt of lightning strikes the Oriental Pearl TV Tower in Shanghai, China.

Cochise County, Arizona

Photograph by Steven Maguire, My Shot

A thunderstorm passes behind the Cochise County courthouse in Arizona. Despite being in a dry part of the country, southeastern Arizona averages 30 to 40 thunderstorms a year.

Bolts on the Water

Photograph by Fotis Mavroudakis, My Shot

Several bolts of lightning strike the water off the coast of Kavala, Greece. Lightning can strike anything that can become electrically charged—including water.

Lightning Over Malaysia

Photograph by Ahmed Arup Kamal, My Shot

Lightning illuminates the horizon behind a Malaysian cityscape.

Johannesburg, South Africa

Photograph by Themba Hadebe, Associated Press

Tall towers are frequent targets of lightning strikes, because there is less air to act as an insulator between the tower and a cloud. In this case, it is the Hillbrow Telkom Tower in Johannesburg, South Africa.

Tucson, Arizona

Photograph by Ralph Wetmore, Getty Images

The Tucson, Arizona, skyline is illuminated by a bolt of lightning.

Hopewell, Virginia

Photograph by Rick Kidd, My Shot

The inhabitants of a powerboat turn on their lights just as a bolt of lightning hits the ground behind it. Covered, walled structures are the best places to take refuge from a thunderstorm.

Desert Lightning

Photograph by Pete Gregoire, My Shot

Saguaro cacti stand in the desert as a thunderstorm rolls overhead. Lightning in dry areas increases the risk of brush fires.

Positive Lightning

Photograph by Kara Swanson, My Shot

Lightning arcs from the top of a cloud to the horizon off the coast of the Bahamas. Lightning that comes from the top of the cloud can be positive lightning, which is rare but can be significantly more powerful than more common negative lightning. It can also strike farther from the cloud, up to 10 miles (16 kilometers) away.

Lightning Strikes Twice

Photograph by Cui Jingyin, Imaginechina/AP

Foshan, China, is hit by two simultaneous lightning strikes.

ستارگان بر فراز دماوند Stars Over Mount Damavand

2012-01-05T17:06:00.000+03:30

Stars Over Mount Damavand

Photograph by Siamak Sabet, Your Shot

Stars whirl in the sky in a long-exposure photo of Mount Damavand in Iran. The mountain, which is part of the Elburz mountain range south of the Caspian Sea, is the highest volcano in Asia and the highest peak in the Middle East.

ستارگان بر فراز دماوند

ستارگان در چرخش بر بالای قله ی دماوند در ایران . دماوند بخشی ار رشته بلندی های البرز است که بلند ترین آتشفشان در قاره ی آسیا و بلندترین قله در خاور میانه است .

Volcanoes آتشفشا ن

2012-01-05T10:31:00.000+03:30

Humanity has long been fascinated with volcanoes, working them into myths and legends in many cultures. Photographing nature's awesome power is no easy task and can be dangerous.

Mount Semeru, seen with an ash plume, is the highest volcano on the Indonesian island of Java, where it is surrounded by the smaller volcanoes Mount Bromo and Mount Batok. Mount Semeru has been in a constant state of eruption since 1967.

Other volcanoes have also put on recent shows, from the Big Island of Hawaii to Mount Etna in Italy and boiling mud pools in Ethiopia.

Volcanoes

Lava Flowing Into the Pacific

Photograph by Stephen Alvarez, National Geographic

With a hiss of steam, lava flows into the Pacific Ocean in Hawaii Volcanoes National Park, Hawaii. Similar flows of molten rock have built up the Hawaiian islands over the course of more than 70 million years.

Mount Etna, Italy

Photograph by Carsten Peter, National Geographic

Perched above the lighted city of Catania, Italy, Mount Etna hurls a fountain of fire skyward as rivers of lava spill down its flanks. In spite of its dazzling displays, Mount Etna is a relatively safe volcano with rare, compact eruptions and slow-flowing lava that gives people a chance to escape.

Liquid Lava on Mount Etna

Photograph by Carsten Peter, National Geographic

A few hundred degrees separates this pool of fiery orange magma in Italy’s Mount Etna from its hardened, gray crust. At nearly 11,000 feet (3,353 meters), Mount Etna is Europe’s highest active volcano.

Volcanic Lightning

Photograph by Peter Vancoillie, Your Shot

A bright bolt of lightning crackles within the ash cloud from the eruption of the Eyjafjallajökull volcano in Iceland in April 2010. Volcanic lightning occurs when roiling ash particles rub against each other and become electrically charged.

Ertale Volcano Crater, Ethiopia

Photograph by Carsten Peter, National Geographic

Climbers mount whorls of lava on the caldera of Ethiopia’s Ertale Volcano as steam escapes from a lava lake in the volcano’s crater, which can reach temperatures of 1,868°F (1,020°C).

Boiling Mud, Ethiopia

Photograph by Carsten Peter, National Geographic

A pool of mud boils near Dallol Volcano, in Ethiopia’s remote Danakil Depression. Volcanic explosion craters such as Dallol form during phreatic eruptions—where rising magma comes into contact with water beneath the surface of the Earth, causing a steam explosion.

Cleveland Volcano, Alaska

Photograph courtesy NASA Earth Observatory

Cleveland Volcano releases a plume of ash that rises almost 20,000 feet (6,000 meters) above the North Pacific Ocean in this aerial photograph. Cleveland Volcano, located in the Aleutian Islands southwest of Alaska, failed to produce an eruption and the plume of ash detached from the volcano two hours after it formed.

Pahoehoe Lava, Hawaii

Photograph by Steve and Donna O'Meara, Volcano Watch International/National Geographic

Pahoehoe lava flows on Kilauea volcano in Hawaii Volcanoes National Park. Unlike aa (pronounced “ah ah”) lava, pahoehoe flows relatively slowly, allowing an insulating skin to form that keeps the temperature close to 2,190°F (about 1,200°C). Aa lava, on the other hand, moves faster and doesn’t have time to develop a skin, resulting in a cooler flow with a more angular texture.

Fern Growing From Lava, Hawaii

Photograph by Frans Lanting, National Geographic

A whisk fern grows from recently cooled lava in Hawaii Volcanoes National Park, Hawaii. Plants can return rapidly to areas affected by volcanic eruptions. Over time, lava and ash break down to form fertile soils ideal for agriculture.

Ash Cloud

Photograph by Snorri Gunnarsson, My Shot

Geese fly past the ash cloud from the eruption of the Eyjafjallajökull volcano that began in April 2010. Ash from the volcano disrupted air traffic in Europe for more than a month.

Stars Over Mount Damavand

Photograph by Siamak Sabet, Your Shot

Lake Laach

Photograph by Hannah Baumert, My Shot

Gas bubbles up from the bottom of Laacher See (or Lake Laach) in Germany. A violent prehistoric eruption caused the Earth's crust to collapse and form a crater that filled with water. The lake lies in an area of Western Germany called the Eifel volcanic field.

Arenal Volcano

Photograph by Lawrence Smith, My Shot

The Arenal Volcano in Costa Rica erupts suddenly in February 2010, turning the sky an ominous yellow-brown. The volcano is one of the most active in the world.

Thurston Lava Tube

Photograph by Kevin Hazelton, My Shot

Lights illuminate the Thurston Lava Tube in the Hawaii Volcanoes National Park. Lava tubes serve as underground pipelines, allowing molten rock to flow under and away from volcanoes.

Lava Falls

Photograph by Snorri Gunnarsson, My Shot

Lava flows into a valley in southern Iceland near the Eyjafjallajökull volcano.

شاید از آغا ز تا امروز، انسان شیفته ی آتشفشان ها بوده و هست ؛ ودر فرهنگ های گونه گون از آن در اسطوره ها و افسانه ها یش بهره گرفته است.

عکس بر داشتن از آتشفشان ها ، کاری است ترسناک و بسیار خطرناک .

آتشفشا ن ِ کوه " سمرو " ، با دودکش و ستونی از خاکستر آتشفشانی ، بلند ترین آتشفشان در جزیره ی اندونزی در " جاوه" است ؛ جایی که بوسیله ی آتشفشان های کوچکتر ِ کوه " برمو"، و کوه " باتوک" در بر گرفته شده است . آتشفشان کوه " سمرو " ، از سال 1967 میلادی تا کنون فعال است .

از آتشفشا ن های جزیره ی بزرگ " هاوایی " ، تا آتشفشان " اتنا " در ایتالیا ، و حوضچه های مواد مذاب و جوشان در "اتیوپی " ، می توان از آتشفشا ن های در حال فوران ِ بسیاری نام برد .

لرزش ها در فوران آتشفشان ِ " ال هیرو " آرام یا فت . Tremors, Eruption at El Hierro Subsiding?

2012-01-05T00:20:00.000+03:30

After two months of eruptions and six months of quakes and tremors, the underwater volcano off the coast of El Hierro appears to be quieting down. A mass of new crust has been building by tens to perhaps a hundred meters, but it is still nowhere near rising above the ocean surface and extending the Canary Island chain.

The Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured this natural-color image of the island and its offshore eruption on December 16, 2011. The eruption is located about one kilometer south-southwest of the town of La Restinga.

The milky green swirls in the Atlantic Ocean are a volcanic brew of steaming lava fragments, bits of rock, heated gas, and other debris that are carried to the west and north by currents. Meanwhile, tremors have been occurring on the north side of the island at depths of 17 to 23 kilometers. Red circles mark the locations of three tremors reported on December 18. The white puffs over the island are clouds, not volcanic emissions.

A swarm of seismic rumblings first began under the island in July 2011, and a submarine eruption was detected in mid-October. But in recent weeks, carbon dioxide emissions have been decreasing, a sign that the supply of magma is decreasing, according to geologist and blogger Erik Klimetti. The number of tremors also has been decreasing, though activity at the site has waxed and waned several times since the event began.

El Hierro is a shield volcano growing along the southwestern edge of the ancient El Golfo volcano. El Golfo collapsed about 130,000 years ago, but the ruddy brown and rugged terrain of the island attests to many years of volcanism in the area. El Hierro last erupted in 1793, according to some historical records, and the area has the greatest concentration of young vents in the Canary Islands.

To view video clips of the seas near the eruption, visit the INVOLCAN web site.

1. References

2. Europapress (2011, December 18) La evolución del tremor en El Hierro indica que la erupción sigue su curso. Accessed December 20, 2011.

3. Klimetti, Erik (2011) Eruptions Blog: El Hierro. Wired Science. Accessed December 20, 2011.

4. Smithsonian/U.S. Geological Survey Global Volcanism Program (2011, December 13) Weekly Volcanic Activity Report.Accessed December 20, 2011.

بدنبا

بدنبال دو ماه فوران و شش ماه لرزشهای پی در پی ، آتشفشا ن ِ زیر دریایی در کناره ی " ال هیرو " نمایان شد . توده ای از مواد ، ساحلی نو را بوجود آورد که بلندی آن به دهها و یا شاید یکصد متر می رسد . این آغاز دگر شکلی است ، که می رود به رشته جزیره ی " قناری " ، افزوده شود .

آتشفشا ن Puyehue-Cordón Caulle

2012-01-04T22:29:00.000+03:30

In early June 2011, Chile’s Puyehue-Cordón Caulle Volcano erupted explosively, sending volcanic ash around the Southern Hemisphere. In late December 2011, activity at the volcano had calmed, but volcanic ash and steam continued to pour through the fissure that opened several months earlier.

The Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured this natural-color image on December 23, 2011. The active fissure lies northwest of the Puyehue caldera, and a plume blows from the fissure toward the west and north. This image shows not just ash but also snow on the volcano surface, including the caldera. Because volcanic ash regularly coats the land surface, the pristine snow probably fell recently.

In a bulletin issued December 26, 2011, Chile’s Servicio Nacional de Geología y Minería (SERNAGEOMIN) characterized the activity over the previous 24 hours as a minor eruption of low intensity.

Reaching an altitude of 2,236 meters (7,336 feet), Puyehue-Cordón Caulle is a stratovolcano, a steep-sloped, conical volcano composed of layers of ash, lava, and rocks released by previous eruptions. This volcano comprises part of the largest active geothermal area in the southern Andes.

1. References

2. Global Volcanism Program. Puyehue-Cordón Caulle. Smithsonian Institution. Accessed December 27, 2011.

3. Servicio Nacional de Geología y Minería. (2011, December 26). Reporte Especial de Actividad Volcánica No 245 Complejo Volcánico Puyehue – Cordón Caulle. (Spanish) Government of Chile. Accessed December 27, 2011.

در اوایل ماه ژوئن آتشفشان با فرستادن خاکستر به جو در نیمکره ی جنوبی ، در کشور شیلی فعالیت دو باره یافت . در اواخر ماه دسامبر 2011 ، فعالیت آتشفشانی با خاکستر دود و غبار در راستای شکافی که ماهها پیش ایجاد شده بود ، ادامه یافت .

این آتشفشانی است از نوع " استراتو ولکانو " ، با نشیب دامنه ای پر شیب ، از فعالیت " ژئو ترمال " گستره ی جنوبی رشته کوههای " آند " .

آتش سوزی در جنگل Fire and the Future of Yellowstone

2012-01-04T22:26:00.000+03:30

The high mountain forests of western North America need fire. Fire returns nutrients to the soil and replaces old stands and ground debris with young forest. Intense fires are a characteristic of the conifer forests, though they occur infrequently—once every 100 to 300 years.

The year 1988 brought one of those infrequent, severe fires to Yellowstone National Park. Drought and high temperatures combined to create extreme fire conditions. Fifty wildfires ignited, seven of which grew into major wildfires. By the end of the year, 793,000 acres had burned.

These images, taken by the Landsat satellites, contrast 1989 and 2011. Burned land is deep red in the 1989 image. By 2011, more than two decades later, the scar faded to tan-orange, but it was still present. Year-to-year images are available in the Earth Observatory’s World of Change article, Burn Recovery in Yellowstone.

Immediately after the fire, grass flourished in the ash-rich soil, followed by young trees. The slender saplings were still not dense enough to hide the burn scar. As these images indicate, it takes many decades for a conifer forest to recover to pre-fire conditions.

Western conifers burn when temperatures are high and plants and soil are dry. Such conditions will come together more frequently as the climate changes over the next century, and fires are already becoming more frequent. A 2011 study combined several climate models to estimate how fire could change in the Yellowstone ecosystem. Yellowstone is near a tipping point, the researchers assert, as warmer, dryer conditions will likely allow large fires to burn as frequently as every 30 years.

When fires occur infrequently, the forest has time to recover. More frequent fires, however, give the conifers little time to grow back. If this occurs, Yellowstone could lose its dense conifer forests and replace them with low montane woodland and grassland by 2050.

1. References

2. National Park Service. (2011, June 2). Wildland fire in Yellowstone. Accessed December 2, 2011.

3. Westerling, A.L., Turner, M.G., Smithwick, E.A.H., Romme, W.H., and Ryan, M.G. (2011, August 9). Continued warming could transform Greater Yellowstone fire regimes by mid-21st century. Proceedings of the National Academy of Sciences, 108 (32), 13165-13170.

آتش سوزی در مناطق بلند جنگلی ، در امریکای شمالی در بازگشت مواد غذایی مورد نیاز اکولوژی منطقه ،نقش بنیادین دارد. این مهم در تناوبی 100 تا 300 سال یکبار رخ می دهد .

دریاچه ی در دهانه ی دود کش آتشفشان Laguna del Maule

2012-01-04T22:21:00.000+03:30

In the Andean mountain range, stretching across the border between Chile and Argentina, lies a volcanic caldera named Laguna del Maule, roughly 15 by 25 kilometers (9 by 15 miles) across. Within the northern part of the caldera lies Maule Lake, which is surrounded by a complex volcanic landscape.

This perspective image is made from data acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite on April 9, 2003. ASTER produces images using infrared, red, and green wavelengths of light. In this image, vegetated areas range in color from red to pink, snow is white, water is black, and bare rock is earth-toned.

Laguna del Maule holds an assortment of volcanic features, including small stratovolcanoes, lava domes, and cinder cones. Some of the most prominent features surrounding Lake Maule are lava flows. Some of those lava flows protrude into the lake, looking a little like dough spreading under its own weight.

Volcanologists estimate that volcanoes at this site have been active over the past 10,000 years, but the date of the last eruption at Laguna del Maule is unknown.

1. References

2. ASTER. (2011, December 9). Maule Volcanic Field, Chile-Argentina. Accessed December 29, 2011.

3. Global Volcanism Program. Laguna del Maule. Smithsonian Institution. Accessed December 29, 2011.

4. Seach, J. Laguna del Maule Volcano. Volcano Live. Accessed December 29, 2011

در رشته کوههای " آند "، در مرز بین دو کشور " شیلی " و " آرژانتین "، " کا لدرا " - دهانه ی آتشفشان- در مجموعه ای ولکانیکی رخ نموده است که در بخش ِ شمالی آن دریاچه ای ایجاد شده است .

آتشفشان شناسان بر این باورند که فوران های آتشفشانی در این ناحیه ، در بیش از 10000 سال پیش فعال بوده است ، با این یادآوری که زمان ِ آخرین فوران هنوز معلوم نیست .

شادمانی سال نو Love and Joy for the New Year

2012-01-04T22:15:00.000+03:30

In November and December 2011, professional and amateur astronomers reveled in observing a sun-grazing comet that dove close to the Sun and survived for a return flight back to the outer solar system. Astronauts on the International Space Station (ISS) enjoyed their own surreal view of the comet as it appeared on Earth’s horizon on the day of the solstice.

ISS Commander Dan Burbank captured a series of digital photographs of Comet Lovejoy on December 21, 2011, as it rose above Earth’s limb. The ISS was passing from eastern Australia southeast toward New Zealand, between 17:35:50 to 17:43:02 Universal Time (6:35 to 6:43 a.m. local time on December 22). Those still images were compiled into a time-lapse video that you can view here. In an interview with WDIV-TV, Burbank described the moment as “the most amazing thing I have ever seen in space.”

Note how the tail of the comet points away from the Sun even as the comet itself is moving in the same direction, away from our star. Every comet has two tails, one of ice and dust, the other of ions, or charged particles. The heat and pressure of sunlight sloughs off the ice and dust, pushing it away from the Sun. Likewise, the solar wind strips ions off of the comet surface, though not necessarily in the same direction as the tail of debris and ice. The ion tail is not visible in this image.

The comet, officially designated C/2011 W3 (Lovejoy), was discovered by Australian amateur astronomer Terry Lovejoy on November 27, 2011. It belongs to a group of comets known as the Kreutz sungrazers, which are thought to be pieces of a much larger comet that broke up centuries ago. The comets are termed sungrazers because their orbits take them quite near—and often into—the Sun.

Comet Lovejoy is remarkable for diving through the superheated solar corona (atmosphere) to within 120,000 kilometers of the Sun’s surface and surviving the encounter. The event was recorded by five NASA and European spacecraft.

In the ISS image above, you can also see green and yellow airglow paralleling the Earth’s horizon line (or limb) before it is overwhelmed by the light of the rising Sun. Airglow is the emission of light by atoms and molecules in the upper atmosphere after they are excited by ultraviolet radiation. In the video, small intermittent flashes of white lightning

ستاره شناسان حرفه ای و آماتور ، در نوامبر و دسامبر سال 2011 ، بیرون پریدن و دو باره در سیستم خورشیدی فرو شدن را با شگفتی مشاهده کردند .

Nyamuragira Volcano Erupts فوران آتشفشا ن " نیاموراجیرا " در جمهوری کنگو "

2011-12-31T18:16:00.001+03:30

On November 6, 2011, after more than a year of relative peace, the Nyamuragira volcano in the Democratic Republic of Congo surged to life. Lava has erupted spectacularly from a fissure low on one of the volcano's flanks and spilled northward, away from populated areas. Nyamuragira is a shield volcano and one of Africa's most active.

For more than a week, cloud cover mostly obscured the view from space until the Advanced Land Imager on NASA’s EO-1 satellite captured images on November 12, 2011. This false-color view combines shortwave infrared, near infrared, and green light. Fresh lava is bright red, an indication that it was active at the time the satellite flew overhead. Billowing, blue-tinged steam clouds rise above the superheated fissure and lava-bathed landscape. In the full-size, wider view (available by link just below the image), the lava lake at nearby Nyiragongo volcano (to the south) glows red through the cloud cover.

A blogger and ranger from Virgunga National Park wrote:

...We hiked a bit further until we came to a section where the vegetation ended and the ground was covered in small pebbles of weightless lava gravel. The thundering roar of the volcano was incredible and the heat of the 100-meter column of lava clearly tangible...The eruption site is truly amazing. It’s located on a flat area, but the sides have been building up around the crack over the last week...The lava has a low silica content resulting in lava with a low viscosity (very fluid), which in turn results in the amazing lava fountain.

Ground-based video of the eruption is available here from the Virunga National Park. Wider satellite views of the landscape around the eruption on November 8 and November 16 are available online through the LANCE/EOSDIS MODIS Rapid Response Team.

1. References

2. Global Volcanism Program (2011, November 8) Nyamuragira. Accessed November 16, 2011.

3. Gorilla.CD Blog (2011, November 13) New Overnight Trek to Nyamulagira Volcano Eruption Site. Accessed November 16, 2011.

4. Klimetti, Erik (2011) Eruptions Blog: Nyamuragira. Accessed November 16, 2011.