"Our loyalties are to the species and the planet. We speak for Earth. Our obligation to survive and flourish is owed not just to ourselves, but also to that Cosmos, ancient and vast, from which we spring." - Carl Sagan
Ice stringers, Lake Michigan
Snow-covered fields appear as geometric patterns on Lake Michigan’s Washington Island in this photograph taken by the crew of the International Space Station. The island is 9 km long (5.6 miles) and lies on Lake Michigan’s western shore, as a continuation of Wisconsin’s Door Peninsula. (Note that north is to the lower left in the image.)
White coastal ice hugs the shoreline and connects Washington Island with Detroit Island and Rock Island. Ice typically accumulates first near land, where cooling is more rapid than in deeper lake water. Two other snow-covered islands (image top left) are small enough and far enough from land to evade the collars of ice.
On the day this image was taken, southwesterly winds were blowing ice into the lake in the form of long, coherent stringers. The thickness of a stringer is related to the length of coastline that feeds it. The smallest northern stringer (image left) is fed by the shortest section of upwind coastline, and the longest (image right) is supplied by the large amount of shore ice around Detroit Island. These dominant winds keep a narrow zone (along the western shore of the lake) clear of ice, even as accumulations in the winter of 2014 reach the highest levels ever recorded in Lake Michigan.
Image source: Astronaut photograph ISS038-E-57977
This is ‘The Spotted Lake’ or ‘Kliluk’ located near the City of Osoyoos in British Columbia, Canada. The lake is full of minerals including; calcium, sodium & magnesium sulphate as well as metals like silver and titanium. In the summer time, most of the water in the lake evaporates, leaving behind over 365 strange pools. Depending on the mineral composition the spots will be white, pale yellow, green or blue in colour. The lake was once considered a sacred healing ground by locals, it is believed to be the most mineralized lake in the world with each of the circles hold a different ‘healing cure’.
For more photos see:http://www.environmentalgraffiti.com/featured/most-psychedelic-lake-on-earth/18196
Margarita Island, Venezuela
Situated in the southern Caribbean Sea about 20 km off of mainland Venezuela’s coast, the island comprises two peninsulas linked by a long, narrow strip of land – called an isthmus.
The eastern part of the island is home to most of the island’s residents, while the Macanao peninsula to the west is dominated by a central mountain range.
Between the peninsulas and cut off from the open sea by the isthmus lies the La Restinga lagoon, a national park that appears as a dark green and blue area in this image.
Recognised as a wetland of international importance by the Ramsar Convention, the area features picturesque mangroves and is an important feeding ground for birds such as herons and flamingos. The shallow waters are home to red snappers, sardines and swordfish – among other types of fish – and oysters grow on the mangrove roots.
Image credit: JAXA/ESA
Warm rivers play role in Arctic sea ice melt
The heat from warm river waters draining into the Arctic Ocean is contributing to the melting of Arctic sea ice each summer, a new NASA study finds.
A research team led by Son Nghiem of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., used satellite data to measure the surface temperature of the waters discharging from a Canadian river into the icy Beaufort Sea during the summer of 2012. They observed a sudden influx of warm river waters into the sea that rapidly warmed the surface layers of the ocean, enhancing the melting of sea ice.
This Arctic process contrasts starkly with those that occur in Antarctica, a frozen continent without any large rivers. The sea ice cover in the Southern Ocean surrounding Antarctica has been relatively stable, while Arctic sea ice has been declining rapidly over the past decade.
"River discharge is a key factor contributing to the high sensitivity of Arctic sea ice to climate change," said Nghiem. "We found that rivers are effective conveyers of heat across immense watersheds in the Northern Hemisphere. These watersheds undergo continental warming in summertime, unleashing an enormous amount of energy into the Arctic Ocean, and enhancing sea ice melt. You don’t have this in Antarctica."
The team said the impacts of these warm river waters are increasing due to three factors. First, the overall volume of water discharged from rivers into the Arctic Ocean has increased. Second, rivers are getting warmer as their watersheds (drainage basins) heat up. And third, Arctic sea ice cover is becoming thinner and more fragmented, making it more vulnerable to rapid melt. In addition, as river heating contributes to earlier and greater loss of the Arctic’s reflective sea ice cover in summer, the amount of solar heat absorbed into the ocean increases, causing even more sea ice to melt.
To demonstrate the extensive intrusion of warm Arctic river waters onto the Arctic sea surface, the team selected the Mackenzie River in western Canada. They chose the summer of 2012 because that year holds the record for the smallest total extent of sea ice measured across the Arctic in the more than 30 years that satellites have been making observations.
The researchers used data from satellite microwave sensors to examine the extent of sea ice in the study area from 1979 to 2012 and compared it to reports of Mackenzie River discharge. “Within this period, we found the record largest extent of open water in the Beaufort Sea occurred in 1998, which corresponds to the year of record high discharge from the river,” noted co-author Ignatius Rigor of the University of Washington in Seattle.
The team analyzed data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Terra satellite to examine sea ice patterns and sea surface temperatures in the Beaufort Sea. They observed that on June 14, 2012, a stretch of landfast sea ice (sea ice that is stuck to the coastline) formed a barrier that held the river discharge close to its delta. After the river water broke through the ice barrier, sometime between June 14 and July 5, the team saw that the average surface temperature of the area of open water increased by 11.7 degrees Fahrenheit (6.5 degrees Celsius).
"When the Mackenzie River’s water is held back behind the sea ice barrier, it accumulates and gets warmer later in the summer," said Nghiem. "So when it breaks through the barrier, it’s like a strong surge, unleashing warmer waters into the Arctic Ocean that are very effective at melting sea ice. Without this ice barrier, the warm river waters would trickle out little by little, and there would be more time for the heat to dissipate to the atmosphere and to the cooler, deeper ocean."
Nghiem’s team has linked this sea ice barrier, which forms recurrently and persistently in this area, to the physical characteristics of the shallow ocean continental shelf, and concludes the seafloor plays a role in delaying river discharge by holding the barrier in place along the shore of the Mackenzie delta.
Image credit: NASA
CALDERAS VS. CRATERS
Calderas and craters, while seeming similar, are two different geological features. The simplest way to distinguish the two is to determine the size of the feature. Craters generally are not larger than 1.00 mile in diameter while calderas can exceed 5-10 miles or even more in diameter.
Not only is size a difference, but also the process by which they form is as well. Calderas normally form from collapse and the process of subsidence. Volcanoes with magma chambers underneath them are the main setting for the formation of calderas. Before the volcano erupts, the magma chamber beneath it is filled with magma and gasses. The pressure of these keep the chamber intact while a volcanic cone or a layer of the earth’s crust sit on top of it. The equilibrium of the weight of the crust and the pressure within the chamber keep it collapsing in on itself. Caldera collapse happens when the lithostatic pressure on the roof of the magma chamber exceeds the chamber pressure by the compressive strength of the overlying rock. For this reason a crater from the result of an explosion is related to cone building and is thus a positive volcanic form, while a caldera is considered a negative passive form.
To form a caldera, there has to be a point where some of that gas or magma is released, usually in the form of a volcanic eruption. The trigger for this eruption could be an earthquake, or it could be as simple as the heat and pressure growing so large that there needs to be a release of energy. The resulting eruption could be a release of magma, gasses, or both. Pyroclastic material can come out in the form of a pyroclastic flow or be spewed into the air. When there is significant empty space gained in the magma chamber, the upper part of the volcanic cone collapses downward filling the empty space beneath.
Below is a picture of Lake Pinatubo at the Mt. Pinatubo caldera in the Philippines. Often mistakenly called “The Crater Lake,” the lake actually sits in a caldera which was formed by the collapse of the volcano’s summit in its 1991 eruption. The Pinatubo caldera is considered a relatively small caldera being only 1.6 mi (2.5 km) in diameter.
More information on the Pinatubo Caldera Lake: http://pubs.usgs.gov/pinatubo/campita/index.html
More information on Mt. Pinatubo: http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-083
Photo Credit: definitelyfilipino.com/blog
the reed flute (or karst) cave in guilin, southern china, was carved out of the karst limestone mountains over 180 million years ago from an underground river that has now settled into a lake. more than 70 ink inscriptions dating back to 792 ce can also be found inside the cave, which was left forgotten for a thousand years before being rediscovered in the 1940s by a group of refugees fleeing japanese troops. photos by james p. nelson, christian ortiz, jesse estes, adam allegro, filip m.a.
Ecuador’s northern highlands are pictured in this image from Envisat.
Near the top left of the image, the southern outskirts of Ecuador’s capital, Quito, appear as white dots. Quito is one of the highest capital cities in the world, at an elevation of 2850 m above sea level.
This area is part of the northern zone of the Andean Volcanic Belt. The belt was formed as a result of the Nazca and Antarctic tectonic plates moving under the South American plate – a geological process called ‘subduction’.
Near the bottom-left corner is the Cotopaxi stratovolcano. It is the second highest summit in the country at about 5900 m and one of Ecuador’s most active volcanoes, erupting more than 50 times since the early 1700s.
On the centre-right side of the image is the Antisana volcano.
What look like white glaciers at the peaks of these mountains are actually artefacts of the radar echo – the surfaces of the summits are more or less directly facing the satellite, so the radar signal reflects straight back to the antenna.
Image credit & copyright: ESA
A thousand miles from nowhere
There is perhaps no better place to get away from it all than Norway’s Bouvet Island. Located in the South Atlantic Ocean between Africa, South America, and Antarctica, this uninhabited, 49-square-kilometer (19-square-mile) shield volcano is one of the most remote islands in the world. The nearest large land mass is the Princess Astrid Coast of Queen Maud Land, Antarctica—1,700 kilometers (1,100 miles) to the south. The nearest inhabited place is Tristan da Cunha, a remote island 2,260 kilometers (1,400 miles) to the northwest that is home to a few hundred people.
On May 26, 2013, the Operational Land Imager (OLI) on Landsat 8 acquired this natural-color image of Bouvet Island. Thick ice covers more than 90 percent of the island year round. Christensen glacier drains the north side; Posadowsky glacier drains the south side. A ring of volcanic black sand beaches encircles most of the island. In many areas, the thick layer of ice stops abruptly at the island’s edge, forming steep ice cliffs that plunge to the beaches and oceans below.
Seen from above, one of the most prominent features is Wilhelmplataet caldera, the large circular depression on the western side of Bouvet. Calderas form following volcanic eruptions as land collapses into newly empty or partly-emptied magma chambers. The most recent eruption occurred on Bouvet about 2,000 years ago.
The island is the southernmost extension of the Mid-Atlantic Ridge, the underwater mountain chain that runs through the Atlantic Ocean and serves as the dividing line between the African and South American plates in the southern hemisphere. Bouvet is located near the triple junction between the African, South American, and Antarctic plates.
The highest point—780-meter Olav Peak—lies midway across the island near the northern coast. Notice the long shadows that the peak casts into the caldera. Although it is not particularly tall, the peak’s remoteness and the fact that it had never been climbed inspired filmmaker Jason Rodi—who had already climbed the highest mountain on all seven continents—to organize an expedition and give it a try. In 2012, a team of filmmakers, adventurers, and artists landed on the island and climbed to the highest point, where they planted a time capsule.
Image credit: NASA Earth Observatory image by Jesse Allen and Robert Simmon, using Landsat data from the U.S. Geological Survey