USA, west Texas - what is this? (Credti: ESA/NASA; by magisstra)
Earth from Space: Central Europe
This Envisat image, acquired on 22 March 2011, features an almost cloud-free look at a large portion of Europe. The Alps, with its white peaks, stand out in contrast against the vast areas still covered in brownish winter foliage. Several dark blue European lakes also stand out. The crescent-shaped Lake Geneva (north of Alps) is Europe’s largest Alpine lake. Its northern part is located in Switzerland, and its southern part in France. With a surface of 218 sq km, Lake Neuchâtel (above Lake Geneva) is the largest lake located entirely in Switzerland. Lake Constance (northeast of Lake Neuchâtel) straddles the borders of Austria, Germany and Switzerland. Italy’s largest and Central Europe’s third largest lake, Garda, sits at the foot of the Alps. (via ESA)
ESA’s GOCE mission has delivered the most accurate model of the ‘geoid’ ever produced, which will be used to further our understanding of how Earth works.
A precise model of Earth’s geoid is crucial for deriving accurate measurements of ocean circulation, sea-level change and terrestrial ice dynamics. The geoid is also used as a reference surface from which to map the topographical features on the planet. In addition, a better understanding of variations in the gravity field will lead to a deeper understanding of Earth’s interior, such as the physics and dynamics associated with volcanic activity and earthquakes. (Credits: ESA/HPF/DLR; via ESA)
Central Tien Shan, China
The Tien Shan—“celestial mountains” in Chinese—is one of the largest continuous mountain ranges in the world, extending approximately 2,500 kilometers (1,550 miles) roughly east-west across Central Asia. This astronaut photograph provides a view of the central Tien Shan, about 64 kilometers (40 miles) east of where the borders of China, Kyrgyzstan, and Kazakhstan meet. […]
In this natural-color image from August 31, 2010, the ocean’s canvas swirls with turquoise, teal, navy, and green, the abstract art of the natural world. The colors were painted by a massive phytoplankton bloom made up of millions of tiny, light-reflecting organisms growing in the sunlit surface waters of the Barents Sea. Such blooms peak every August in the Barents Sea.
The variations in color are caused by different species and concentrations of phytoplankton. The bright blue colors are probably from coccolithophores, a type of phytoplankton that is coated in a chalky shell that reflects light, turning the ocean a milky turquoise. Coccolithophores dominate the Barents Sea in August. Shades of green are likely from diatoms, another type of phytoplankton. Diatoms usually dominate the Barents Sea earlier in the year, giving way to coccolithophores in the late summer. However, field measurements of previous August blooms have also turned up high concentrations of diatoms.
The Barents Sea is a shallow sea sandwiched between the coastline of northern Russia and Scandinavia and the islands of Svalbard, Franz Josef Land, and Novaya Zemlya. Within the shallow basin, currents carrying warm, salty water from the Atlantic collide with currents carrying cold, fresher water from the Arctic. During the winter, strong winds drive the currents and mix the waters. When winter’s sea ice retreats and light returns in the spring, diatoms thrive, typically peaking in a large bloom in late May.
The shift between diatoms and coccolithophores occurs as the Barents Sea changes during the summer months. Throughout summer, perpetual light falls on the waters, gradually warming the surface. Eventually, the ocean stratifies into layers, with warm water sitting on top of cooler water. The diatoms deplete most of the nutrients in the surface waters and stop growing. Coccolithophores, on the other hand, do well in warm, nutrient-depleted water with a lot of light. In the Barents Sea, these conditions are strongest in August.
The shifting conditions and corresponding change in species lead to strikingly beautiful multicolored blooms such as this one. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired this image.
(via Phytoplankton Bloom in the Barents Sea : Natural Hazards)