[Waspie_Dwarf]

Ship-Wave-Shaped Clouds, Bouvet Island, South Atlantic Ocean


Credit: Jeff Schmaltz MODIS Land Rapid Response Team, NASA GSFC

Satellite: Terra
Date Acquired: 12/06/2007

The cloud patterns seen in this image, acquired by the MODIS on the Terra satellite on December 6, 2007, resemble ship waves or "Kelvin ship waves". These are the V-shaped wakes left by moving objects like ships, or even ducks. The pattern is not coincidental; wind behaves like a fluid, so when it encounters an obstacle, it must move around it, leaving behind a wake or a visible wave pattern. As the air crested a wave, it cooled and clouds formed. Then, as the air sank into the trough, the air warmed, and clouds did not form. This pattern repeated itself, with clouds appearing at the peak of every wave. In this case, the obstacle is an island. As the wind flows past the island, it is swept around and over it leaving a wake similar to that of a ship - hence the name "ship-wave-shaped" clouds.

In this case, the wave clouds are being caused by the Bouvet Island, in the South Atlantic Ocean.

Source: MODIS - Image of the Day

[Waspie_Dwarf]

Wellington, New Zealand

Click here to view full image (634 kb)

New Zealand’s capital, Wellington, sits at the southwestern tip of North Island near the Cook Strait. The city in the second largest in New Zealand (after Auckland), and at 41 south latitude, it is the southernmost capital city in the world. The North and South Islands of New Zealand are located along the active Australian-Pacific tectonic plate boundary. The glancing collision of these two tectonic plates results in uplift of the land surface, expressed as low hills on North Island and the Southern Alps on South Island.

Local topography visible in this astronaut photograph is a result of these tectonic forces and weathering, and the topography has exerted a strong influence on the shape of the city. The tightly clustered white rooftops of the central business district are visible to the south of the Westpac Stadium between vegetated (green) northeast-southwest trending ridges. Lower density development (gray gridded areas with scattered white rooftops) has spread eastwards along the Miramar Peninsula.

Five major faults run through the Wellington metropolitan area; the largest magnitude earthquake recorded in New Zealand (about 8.2 magnitude) occurred in 1855 on one of these faults. Recognizing the potential seismic hazard, the city has adopted building codes that maximize structural resistance to earthquake damage.

Astronaut photograph, ISS016-E-5121 was acquired October 21, 2007, by the Expedition 15 crew with a Kodak 760C digital camera using an 800 mm lens. The images are provided by the ISS Crew Earth Observations experiment and the Image Science & Analysis Laboratory, Johnson Space Center. The image in this article has been cropped and enhanced to improve contrast. Lens artifacts have been removed. The International Space Station Program supports the laboratory to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC NASA/JSC Gateway to Astronaut Photography of Earth.

Source: NASA - Earth Observatory - Image of the Day

[Waspie_Dwarf]

Nyamuragira and Nyiragongo

Click here to view full image (5239 kb)

In central Africa, in the Democratic Republic of the Congo, sit two volcanoes: Nyiragongo and Nyamuragira. Besides their proximity to Lake Kivu in the south, these volcanoes share the capacity for destruction, each having produced its share of catastrophic eruptions since the early twentieth century. Yet these volcanoes differ markedly from each other, one being a low-profiled structure rising subtly from the plain, and the other sporting steep slopes.

NASA’s Landsat 7 satellite captured this false-color image of Nyamuragira and Nyiragongo on January 31, 2007, about a year after Nyiragongo sent a devastating lava flow through the town of Goma. Lava flows from neighboring Nyamuragira, however, are more conspicuous in this picture, contrasting with the lush green vegetation with their somber shades of brown and purple-black. Nyiragongo shows evidence of its own activity. The deep pink dot at its summit is a hotspot where the sensor has detected unusually warm surface temperatures. The bright white dots are clouds, likely resulting from water vapor released by the volcano. Near the clouds is a small area of peacock blue, also part of the volcanic plume. Along the shores of Lake Kivu, areas of purple-brown indicate bare ground and human-made structures.

At 3,470 meters (11,384 feet) high, Nyiragongo Volcano is a stratovolcano, a steep-sloped structure composed of alternating layers of solidified ash, hardened lava, and rocks ejected by previous eruptions. Prior to its 2002 eruption, this volcano wrought havoc in 1977 when it emptied a lava lake at its summit and caused a very fluid, fast-moving lava flow.

In contrast to its neighbor, Nyamuragira (or Nyamulagira) Volcano is a shield volcano, composed of old lava flows, that derives its description from its resemblance to an ancient warrior shield. Lava flows from this volcano cover some 1,500 square kilometers (580 square miles), and the volcano rises very gradually, reaching an altitude of 3,058 meters (10,033 feet). Despite its subtler shape, this volcano drained its own lava lake in 1938, sending lava flows all the way to Lake Kivu. For a three-dimensional image of these contrasting volcanoes, see Nyiragongo Lava Flows.

These volcanoes’ tendency to release catastrophic lava flows prompted volcanologists to look for innovative ways to monitor their behavior, and even develop “smart” systems that can act independently to collect observations as quickly as possible. See the Earth Observatory feature Observing Volcanoes, Satellite Thinks for Itself for more information.

You can also download a 28.5-meter-resolution KMZ file of the Nyamuragira and Nyiragongo volcanoes suitable for use with Google Earth.

NASA image created by Jesse Allen, using Landsat data provided by the University of Maryland’s Global Land Cover Facility.

Source: NASA - Earth Observatory - Image of the Day

[Waspie_Dwarf]

First Snow in US Northeast


Credit: Jeff Schmaltz MODIS Land Rapid Response Team, NASA GSFC

Satellite: Terra
Date Acquired: 12/06/2007

A string of storms brought the season's first snow to the eastern United States from the mid-Atlantic states to New England during the first week of December 2007. By December 6, most of the clouds had cleared, providing the MODIS on NASA's Terra satellite this view of the snow-covered landscape. The snow highlights the contours of the land. Waves and curves follow the gentle folds of the Appalachian Mountains through Virginia, West Virginia, Maryland, and Pennsylvania. The more rugged mountains of New Hampshire, Vermont, and New York wrinkle the surface of the land.

The snow also makes rivers and lakes more visible than they might otherwise be. The dark blue-green Finger Lakes of upstate New York pop out against the surrounding white land. The long narrow lakes formed when glaciers scoured, deepened, and eventually dammed stream valleys. The lakes point north and northwest to the shores of Lake Ontario, portions of which are visible beneath a bank of clouds in this image. The northern shore of Lake Erie similarly peaks through the clouds to the west. In the far north, particularly in Maine and Canada, lakes have already started to freeze. The ice is a smooth, bright white surface in contrast to the slightly darker land.

To the south, snow-covered Maryland surrounds the northern Chesapeake Bay, starkly outlining the ragged shoreline where rivers and streams enter the bay. The largest river flowing into the Chesapeake is the Susquehanna, which cuts southeast across the Appalachian Mountains of Pennsylvania.

Source: MODIS - Image of the Day

[Waspie_Dwarf]

Summit Close Ups of Two African Volcanoes

High-resolution Images

Nyamuragira (6.4 MB JPEG)

Nyiragongo (10.2 MB JPEG)

Two East African volcanoes, Nyamuragira and Nyiragongo, account for 40 percent of all recorded eruptions in Africa. The two volcanoes sit along the edge of the Western Rift, part of a giant crack in the Earth’s crust that runs for thousands of miles from the Middle East southward to central Africa. In addition to their shared tendency to produce unusually fast-moving lava flows, the two volcanoes have an even rarer trait in common. The crater of each has periodically contained a lava lake, a huge volume of molten lava pooling in a high-walled summit crater. The lava lakes can drain during eruptions, either spilling over the rim of the crater or bursting from a fissure or vent on the flank.

This pair of high-resolution images from the commercial Ikonos satellite shows the craters of Nyamuragira (top) and Nyiragongo (bottom), both of which are located at the far eastern edge of Democratic Republic of Congo, north of Lake Kivu. Nyamuragira’s larger but shallower caldera is filled with solidified lava flows (purplish gray), some of which spill over the rim and down the flanks to the north and southeast. According to the Smithsonian Global Volcanism Program, the most recent lava lake in the Nyamuragira crater drained during an eruption in 1938; the remnants of that activity are the lighter-purple lavas, mostly in the southwestern part of the crater. Volcanologists from the local, Goma Observatory reported observing a 300-meter-wide lava lake appearing in a pit to the north-northeast of the caldera during a 2004 eruption. More recent eruptions, such as one in late November 2006 that threatened the town of Sake, have occurred from vents on the volcano’s broad, gently sloping flanks.

By contrast, the lava lake in Nyiragongo has drained and refilled several times during eruptions in the past few decades. Evidence of its simmering presence is provided by the plume of smoke and/or steam that billows from crater. In 2002, Nyiragongo’s lava lake drained during a flank eruption on the southern slopes. That lava flow raced into the city of Goma, killing several dozen people.

To read about how NASA scientists are using advanced software and artificial intelligence technology to train satellites to self-direct observations of dangerous volcanoes, please see the Earth Observatory feature story Observing Volcanoes, Satellite Thinks for Itself.

References

Smithsonian Global Volcanism Program. Nyamuragira. Accessed December 10, 2007.

Smithsonian Global Volcanism Network. (2004). New eruption on 8 May spawns cones, lava lake, fountains, and lava flows. Bulletin of the Global Volcanism Network, 29 (4). Accessed December 10, 2007.

USGS Cascades Volcano Observatory. (2003). Lava Lakes. Accessed December 10, 2007.

USGS Cascades Volcano Observatory. (2003). Africa Volcanoes and Volcanics. Accessed December 10, 2007.

Images © Geoeye.

Source: NASA - Earth Observatory - Image of the Day

[Waspie_Dwarf]

Fires on Kangaroo Island, South Australia


Credit: Jeff Schmaltz MODIS Land Rapid Response Team, NASA GSFC

Satellite: Aqua
Date Acquired: 12/06/2007

On December 8, 2007, the MODIS on NASA's Aqua satellite captured this image of fires burning on Kangaroo Island, just off the coast of South Australia. Places where the sensor detected active fire are outlined in red.

Thick, gray-brown smoke spreads eastward over Encounter Bay, the body of water between Kangaroo Island and the mainland. According to news reports from the Australian Broadcasting Corporation, the fires, many of them burning in parks and conservations areas, were still out of control as of December 10.

Also visible on the image is Adelaide - a city on the mainland, located near the top right-hand corner of the image, on the Gulf of St. Vincent, which is to the west. The Yorke Peninsula is in the top center of the image.

Source: MODIS - Image of the Day

[Waspie_Dwarf]

Fires on Kangaroo Island

Click here to view full image (834 kb)

Off the southern coast of Australia, not far from the city of Adelaide, is Kangaroo Island. Five times the size of Singapore, this island is known for its abundant wildlife. In December 2007, as the Australian summer began, wildfires threatened both the island’s wildlife and many of its human inhabitants. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this image on December 12, 2007, after the fires had already burned for several days.

In this image, red outlines mark areas where the satellite sensor detected scorching conditions associated with wildfires. One fire, near Cape Gantheaume Conservation Park, emits negligible smoke. In Flinders Chase National Park, however, thick smoke from the fires completely obscures the view of the land surface. The thick smoke blows westward over the ocean. Where not hidden by smoke or isolated clouds, the island’s surface appears in shades of brown and brownish-green, especially Gantheaume Conservation Park.

According to The Sydney Morning Herald, fires along the northern and southern coast of Kangaroo Island had been largely contained by December 12. In contrast, the bushfires in Flinders Chase National Park had already consumed 11,000 hectares (about 27,000 acres) and continued burning. The weather forecast called for increased winds and warmer temperatures, expected to exacerbate the blaze. Collectively, the fires that burned on Kangaroo Island during the previous week had scorched more than 30,000 hectares (74,000 acres) and claimed at least one human life.

NASA image courtesy the MODIS Rapid Response Team at NASA GSFC. The Rapid Response Team provides daily images of this region.

Source: NASA - Earth Observatory - Image of the Day

[Waspie_Dwarf]

Haze along the Himalaya


Credit: Jeff Schmaltz MODIS Land Rapid Response Team, NASA GSFC

Satellite: Terra
Date Acquired: 12/10/2007

Haze hugged the southern slopes of the Himalaya on December 10, 2007. The MODIS on NASA's Terra satellite took this picture the same day. This image shows the region around Kanpur, India, with dingy gray haze blanketing the area. Multiple factors can contribute to haze near the Himalaya in late fall and early winter.

Black lines show country borders - Kanpur, India's border with Nepal runs right along the haze. Nepal is the strip covered with clouds in the top right-hand corner of the image.

Source: MODIS - Image of the Day

[Waspie_Dwarf]

Oil Spill off South Korea

Click here to view full image (5270 kb)

Crude oil from the wrecked 146,000-ton tanker, Hebei Spirit, is seen polluting the sea off South Korea in this Envisat image, provided by the European Space Agency. The image was acquired on December 11, 2007, at 10:40 a.m., local time (01:40 UTC) by the Advanced Synthetic Aperture Radar (ASAR) aboard ESA’s Envisat satellite.

Oil spills are hard to see in photo-like satellite images because the ocean surface is already dark. Radars, which shoot energy pulses toward the surface and measure the intensity of the signal that returns to the satellite, have a better chance at detecting oil. The presence of oil on the sea surface damps down smaller, wind-generated waves. It is these waves that typically reflect the radar signal back to the satellite. When the waves are damped, the energy reflected by the ocean surface decreases, causing oil slicks to appear as dark areas on an otherwise brighter sea.

In this image, the dark oil covers the coastal waters of the Yellow Sea southwest of Seoul, South Korea. More than 10,000 tons of oil from the tanker were reported to have leaked into the sea after the ship collided with another vessel on Friday, December 7, 2007. As the image shows, the oil washed onto the beaches. The South Korean government declared the coastal regions shown here disaster areas.

Like other space-based radar instruments, ASAR essentially provides its own source of illumination and operates at longer wavelengths than optical (camera-like) sensors. This technology enables it to observe the Earth’s surface at night and through thick cloud cover.

Image and interpretation courtesy the European Space Agency.

Source: NASA - Earth Observatory - Image of the Day

[Waspie_Dwarf]

Earth from Space: Quebec province

Click on the image for high resolution version

14 December 2007
This Envisat image features the southern part of Canada’s Quebec province, which occupies a territory nearly three times the size of France.

The mighty Saint Lawrence River is visible flowing from the southwest to the northeast. Beginning from Lake Ontario (not visible), the river flows northeast past Montreal (visible as the whitish area at the confluence of the two rivers) and Quebec City (the whitish area visible on the north bank of the river) to the Gulf of St. Lawrence.

Saint Lawrence River is 1197 km long and its drainage basin covers some 1 million km², of which 505 000 km² is in the United States. The river, which connects the Great Lakes with the Atlantic Ocean, is the primary drainage of the Great Lakes Basin.

Quebec City is the capital of the province of Quebec. The Laurentian Mountains lie to the north of the city.

The dark blue lake visible at the top right of the image is Lac Saint-Jean, which is situated some 170 km north of the Saint Lawrence River. It covers an area of 1003 km² and is relatively shallow at 63 m deep.

Lac Saint-Jean is fed by dozens of small rivers and discharges through two outlets into the Saguenay River (visible), which then drains Lac Saint-Jean into the St. Lawrence River at Tadoussac, some 190 km northeast of Quebec City.

This image was acquired by Envisat's Medium Resolution Imaging Spectrometer (MERIS) instrument on 26 October 2007, working in Full Resolution mode to provide a spatial resolution of 300 metres.

Source: ESA - Observing the Earth - Image of the Week

[Waspie_Dwarf]

Wow, is it really nearly 2 years since I last posted in this thread? It's way past time that I did so again, so here is NASA's Image of the day:

---

Spring Bloom in New Zealand Waters

Off the east coast of New Zealand, cold rivers of water that have branched off from the Antarctic Circumpolar Current flow north past the South Island and converge with warmer waters flowing south past the North Island. The surface waters of this meeting place are New Zealand's most biologically productive. This image of the area on October 25, 2009, from the MODIS sensor on NASA’s Aqua satellite shows the basis for that productivity: large blooms of plantlike organisms called phytoplankton.

Phytoplankton use chlorophyll and other pigments to absorb sunlight for photosynthesis, and when they grow in large numbers, they change the way the ocean surface reflects sunlight. Caught up in eddies and currents, the blooms create intricate patterns of blues and greens that spread across thousands of square kilometers of the sea surface.

Especially bright blue areas may indicate the presence of phytoplankton called coccolithophores, which are coated with calcium-carbonate (chalk) scales that are very reflective. The duller greenish-brown areas of the bloom may be diatoms, which have a silica-based covering.

In addition to their importance as the foundation of the ocean food web, phytoplankton play a key role in the climate because, like plants on land, they absorb carbon dioxide from the atmosphere. When they die, they sink to the ocean floor where the carbon they took from the atmosphere is stored for thousands of years.

Photo Credit: NASA/MODIS Rapid Response/Jeff Schmaltz. Caption Credit: Rebecca Lindsey, NASA Earth Observatory.

Source: NASA - Multimedia - Image of the Day Gallery

This post has been edited by Waspie_Dwarf: 05 November 2009 - 08:37 PM
Reason for edit:: typo.

[Waspie_Dwarf]

Earth from Space: Northern Sweden


Click on the image for high resolution version

6 November 2009
The vast and widely varied landscape of northern Sweden, just below the Arctic Circle, is shown in this SPOT-4 image. Mountains, lakes, rivers, streams, valleys, rocks, boulders and barren cliffs make up this area that is often called ‘Europe’s last wilderness’.

This area is commonly referred to as Lapland, which constitutes the western parts of Norrbotten (upper right) and Västerbotten (lower right) counties.

Norrbotten houses eight of Sweden’s 28 national parks, including the oldest and largest ones. All of Sweden's mountains above 1800 m are located here. Europe’s largest nature reserve, Vindelfjällen, is located in the northwestern part of Västerbotten.

The area above the Arctic Circle is often referred to as the ‘Land of the Midnight Sun’ because of a natural occurring phenomenon that allows the sun to shine for at least 24 hours from May until mid-July. The opposite phenomenon, called polar night, occurs in winter when the sun sits below the horizon, producing very little or no sunlight.

These phenomena occur in latitudes north of the Arctic Circle and south of the Antarctic Circle. As Earth orbits the sun, its tilt places the North Pole towards the sun in the summer and away from the sun in the winter.

The Aurora Borealis, also called Northern Lights, can also be seen in this area from September to October and from March to April. The aurora is a result of high-speed electrons and protons from the sun entering into the atmosphere and colliding with air molecules, causing them to emit light.

To the north of this image is the famous Jukkasjärvi Ice Hotel, the world’s largest igloo. As Arctic temperatures drop each fall, the local inhabitants rebuild this hotel from 1000 to 2000 tons of snow.

SPOT-4 acquired this image on 9 May 2006. SPOT-4 is supported by ESA as a 'Third Party Mission', which means ESA utilises its multi-mission European ground infrastructure and expertise to acquire, process and distribute data from the satellite to its wide user community.

Source: ESA - Observing the Earth - Image of the Week

[Ufo Believer]

Magnificent. Really Cool.

[Waspie_Dwarf]

Earth from Space: Depression in North Atlantic


Click on the image for high resolution version

13 November 2009
This Envisat image captures a depression, or low pressure system, covering most of the North Sea, an arm of the Atlantic Ocean, on Monday 2 November.

Low pressure systems are storms that rotate around a central area of extreme low pressure, pulling in air from the surrounding area. Winds begin rushing inwards and upwards around this low-pressure zone. As the air rises, it cools and forms clouds and precipitation.

The area of low pressure developed to the southwest of Britain on Saturday night. Heavy rains spread through England (visible), Wales (partly visible), Northern Ireland and Scotland (partly visible) on Sunday morning.

Scotland was one of the worst hit areas, with 13 flood warnings issued. According to the UK Met Office, 53 mm of rain fell in the Scottish city of Aberdeen on Sunday, nearly three-quarters of the usual rainfall for the month of November.

The various colours of green visible in the sea around the River Thames in England are due to sediments being transported in the water. Western France is visible in the bottom right.

Envisat’s Medium Resolution Imaging Spectrometer (MERIS) optical instrument acquired this image working in Full Resolution mode to provide a spatial resolution of 300 m.

Source: ESA - Observing the Earth - Image of the Week

[Waspie_Dwarf]

Earth from Space: ‘Sea of the Viennese’


Click on the image for high resolution version

20 November 2009
Lake Neusiedl, straddling the Austrian–Hungarian border, is featured in this satellite image. The largest steppe lake in Central Europe, Neusiedl covers an area around 315 sq km, with 240 sq km situated in Austria and 75 sq km in Hungary (bottom).

Reeds, ponds and wetland areas that provide important habitat for fauna and flora as well as for migratory birds surround Lake Neusiedl, which is a protected wildlife sanctuary.

In addition to the natural landscape and extraordinary wildlife, this is a highly developed area with more than 1500 landowners whose patches of land are now an integrated part of the protected area.

Lake Neusiedl, called the 'Sea of the Viennese' due to its close proximity to Vienna, has totally dried up at least 100 times since it formed around 16 000 BC. Since the lake provides humidity and temperature buffering, the drying-up of the seabed causes major environmental disruptions. The Austro-Hungarian Water Commission has been controlling the water level via a dam since 1956.

The unique landscape of the Lake Neusiedl region, which encompasses an area of around 747 sq km around the lake, was designated a UNESCO World Heritage Site in 2001.

The Leitha Mountain range, called 'Leithaberg' by locals, is visible in green northwest of the lake. The soils of the mountains, which are covered by dense deciduous woodland, are dominated by slate and marine limestone.

The Seewinkel area, the largest inland salt region in Austria and one of the most important in Europe, is located east of the lake. As visible, this area is characterised by numerous saline alkaline lakes scattered among grazed meadows.

The sunny climate of the area, the soil and the lake’s ability to moderate extreme climate provide optimal conditions for the wine industry; today, wineries are located all around the region.

The famous Danube River, one of Europe's main traffic arteries, is visible running across the top of the image. The Danube has its source in Germany's Black Forest and flows through nine European countries for a distance of about 2850 km.

An aircraft condensation trail, or 'contrail', is visible in white stretching across the image centre. A shadow of the contrail is visible along the top of the image.

SPOT-4 acquired this image on 9 October 2006 with a spatial resolution of 20 m. SPOT-4 is supported by ESA as a 'Third Party Mission', which means ESA utilises its multi-mission European ground infrastructure and expertise to acquire, process and distribute data from the satellite to its wide user community. The SPOT system was designed by the French space agency (CNES) and is operated by Spot Image.

Source: ESA - Observing the Earth - Image of the Week