SismoscholarLa sismologia nelle scuole
Le immagini satellitari più belle fornite dall'ESA
9 December 2011The Tian Shan mountains, stretching across the border region of Kazakhstan, Kyrgyzstan and western China, are pictured in this Envisat image.As one of the longest mountain ranges in Central Asia, the Tian Shan mountain range is about 2800 km long. They are home to evergreen spruce trees at altitudes of over 2000 m, while the lower slopes have natural forests of wild walnuts and apples. The large, dark lake that splits the mountain range in eastern Kyrgyzstan (lower-left corner) is the second largest saline lake after the Caspian Sea. Named Issyk Kul - meaning ‘hot lake’ in the Kyrgyz language because it never freezes over - it covers an area of over 6000 sq km and reaches over 600 m deep.This was a stopover point on the Silk Road from the Far East to Europe, and some historians say it was the point of origin for the Black Death during the 14th century.In the upper-right corner are the Dzungarian Basin and its Gurbantunggut Desert in light brown.This image was acquired on 7 September 2011 by Envisat’s Medium Resolution Imaging Spectrometer.
21 October 2011This Envisat image is dominated by the island of Crete separating the Aegean and Libyan Seas in the eastern Mediterranean. The largest and most populous of the Greek islands, Crete is home to numerous beaches, fertile plateaus, caves and high mountains.Located at the centre of the island, Mount Psiloritis (also known as Mount Ida) towers over the others at 2454 m. According to Greek mythology, the god of sky and thunder – Zeus – was born in a cave here.At the top of the image we can see the southern portion of the Cyclades island group, including the islands of Milos, Ios, Anafi and Santorini.While most of these islands are peaks of a submerged mountainous terrain, Milos and Santorini (the two backward-C-shaped islands) are volcanic.This image is a compilation of three passes by Envisat’s radar on 11 December 2010, 10 January and 11 March 2011. Each is assigned a colour (red, green and blue) and combined to produce this representation. New colours reveal changes in the surface between Envisat’s passes.
22 July 2011This Envisat image is dominated by southern Argentina, with the mountainous terrain of the Andes in Chile to the west (left). The lush, snow-capped mountains slope into the arid inland areas of Argentina’s Chubut province and neighbouring Santa Cruz province to its south – home to a series of plateaus and depressions.In the centre, two lakes in Argentina’s Chubut province are visible. Lake Musters’ depth of about 20 m gives it a dark hue, while Lake Colhué Huapi fills a shallow depression, about 2 m deep.The inlet cutting into the east coast of Argentina is the San Jorge Gulf, measuring about 228 km at its mouth. Along its innermost coast lies Comodoro Rivadavia, a city famous for its lobsters and spider crabs.The bright white spot in the lower-left corner of the image is the Northern Patagonian Ice Field in southern Chile. Satellite images show that the glaciers here have been rapidly retreating over the past years. However, it is still the largest continuous mass of ice outside of the polar regions.This image was acquired on 3 June 2011 by Envisat’s Medium Resolution Imaging Spectrometer.
This image from Japan’s ALOS Earth observation satellite shows Lake Sulunga and surrounding areas in central Tanzania. Measuring about 25 km wide and 42 km long, Sulunga lies 45 km west of the capital, Dodoma.Sulunga straddles the border of the Dodoma and Singida regions. Singida is one of the poorest regions in Tanzania even though it is home to part of the Kizigo Game Reserve, which spreads into the two regions to the south. The major sources of revenue in the region are agriculture and tourism. Along with Kenya, Tanzania is one of the most visited East African countries for safari and beach holidays. A major road running east to west can be seen north of the lake with a railway running nearby. Agriculture is evident in the surrounding areas. This semi-arid area of the country experiences frequent droughts. The Advanced Land Observation Satellite captured this image on 25 June 2009 with its AVNIR-2 Advanced Visible and Near Infrared Radiometer. ALOS was supported as a Third Party Mission, which means that ESA used its multi-mission ground systems to acquire, process, distribute and archive data from the satellite to its user community. In April 2011 the satellite abruptly lost power while mapping Japan’s tsunami-hit coastline.
15 April 2011Envisat captures dust and sand from the Algerian Sahara Desert, located in northern Africa, blowing west across the Atlantic Ocean last week. Stretching across the eastern Atlantic, strong winds carry the plume over the northwestern tip of the Iberian Peninsula (bottom), the western tip of France, the southwestern tip of England (top right) and the southwestern coast of Ireland (top left). Dust from the Sahara Desert – the world’s largest desert, encompassing around 8.6 million sq km – can be transported over thousands of kilometres by atmospheric convection currents. These convection currents form when warm, lighter air rises and cold, heavier air sinks.Sandstorms are very common over the Sahara, and large concentrations of the dust can be found in the tropical Atlantic and the Caribbean. The dust contains many nutrients, including nitrogen, phosphorus and iron, which act as a fertiliser and stimulate the production of massive plankton blooms.In this image, plankton blooms are visible in the Atlantic as blue and green swirls. (The various shades of green and tan in the English Channel and around Wales are due to sediments being transported in the water.) Plankton are microscopic marine plants that drift on or near the surface of the sea and are the basic food on which all other marine life depends. They contain chlorophyll pigments and are able to convert inorganic compounds, such as water, nitrogen and carbon, into complex organic materials.With their ability to 'digest' these compounds, they remove as much carbon dioxide from the atmosphere as terrestrial plants. As a result, the oceans have a profound influence on climate. Since plankton influence the amount of carbon in the atmosphere, it is important to monitor and model them into calculations of future climate change.Although some types of plankton are individually microscopic, the chlorophyll they use for photosynthesis collectively tints the colour of the surrounding ocean waters. This allows dedicated 'ocean colour' satellite sensors, such as Envisat's Medium Resolution Imaging Spectrometer (MERIS), to detect them from space.MERIS acquired this image on 8 April at a resolution of 300 m.