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Alūksne Upland
Alūksne Upland (Alūksne Highland; ) is a hilly area of higher elevation in eastern Latvia, in the historical region of Vidzeme. Sometimes it is referred to as the East Vidzeme Upland, to distinguish it from another hilly area of Vidzeme, Vidzeme Upland, also known as the "Central Vidzeme Upland". Geography The upland continues into the neighbouring Estonia as the Haanja Upland. The Alūksne Upland is part of the drainage divide between Gauja and Daugava river basins. Geology and geomorphology The Alūksne Upland forms an "isometric insular" glacial upland that originated as a bedrock-cored plateau when converging ice lobes stalled and deposited till. Its summit plateau ranges from 190 to 230 m a.s.l., rising 20–40 m above adjacent lowlands, and is mantled by 6–8 m (locally up to 28.5 m) of glaciolacustrine clays and silts laid down in ice-dammed lakes during the final stages of the Weichselian deglaciation. Climate The Alūksne Upland has a humid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alūksne Päikese Sild
Alūksne () is a town on the shores of Lake Alūksne in the Vidzeme region of Latvia near the borders with Estonia and Russia. It is the seat of the Alūksne municipality. Alūksne is the highest elevated Latvian city, located in East Vidzeme Upland at 217 m above sea level. The high elevation of the city affects the social and physical arrangement of the place. History The region around Lake Alūksne was originally settled by Finnic-speaking tribes, and from the 8th-12th centuries by Latgalians. The date of settlement at the current location of the town, then known as ''Olysta'', ''Alyst'', and ''Volyst'', is given in the chronicles of Pskov as 1284. The later name "Alūksne" comes from the Latgalian word ''olūksna'', meaning a spring in the forest. The Latgalian inhabitants of the settlement were conquered by the German crusaders of the Livonian Order in 1224. In 1284, they built a wooden castle named Marienburg (after Mary, the mother of Jesus) on a nearby island, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Height Above Mean Sea Level
Height above mean sea level is a measure of a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level varies in different countries due to different reference points and historic measurement periods. Climate change and other forces can cause sea levels and elevations to vary over time. Uses Elevation or altitude above sea level is a standard measurement for: * Geographic locations such as towns, mountains and other landmarks. * The top of buildings and other structures. * Mining infrastructure, particularly underground. * Flying objects such as airplanes or helicopters below a Transition Altitude defined by local regulations. Units and abbreviations Elevation or altitude is generally expressed as "metres above mean sea level" in the metric system, or " feet above mean sea level" in United States customary and imperial units. Comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discharge (hydrology)
In hydrology, discharge is the volumetric flow rate (volume per time, in units of m3/h or ft3/h) of a stream. It equals the product of average flow velocity (with dimension of length per time, in m/h or ft/h) and the cross-sectional area (in m2 or ft2). It includes any suspended solids (e.g. sediment), dissolved chemicals like (aq), or biologic material (e.g. diatoms) in addition to the water itself. Terms may vary between disciplines. For example, a fluvial hydrologist studying natural river systems may define discharge as streamflow, whereas an engineer operating a reservoir system may equate it with outflow, contrasted with inflow. Formulation A discharge is a measure of the quantity of any fluid flow over unit time. The quantity may be either volume or mass. Thus the water discharge of a tap (faucet) can be measured with a measuring jug and a stopwatch. Here the discharge might be 1 litre per 15 seconds, equivalent to 67 ml/second or 4 litres/minute. This is an average meas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Cover
Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the ocean's ecosystems. Due to the action of winds, currents and temperature fluctuations, sea ice is very dynamic, leading to a wide variety of ice types and features. Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Depending on location, sea ice expanses may also incorporate icebergs. General features and dynamics Sea ice does not simply grow and melt. During its lifespan, it is v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwealth usage), snow, ice pellets, graupel and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor (reaching 100% relative humidity), so that the water condenses and "precipitates" or falls. Thus, fog and mist are not precipitation; their water vapor does not condense sufficiently to precipitate, so fog and mist do not fall. (Such a non-precipitating combination is a colloid.) Two processes, possibly acting together, can lead to air becoming saturated with water vapor: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are calle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Climate
Continental climates often have a significant annual variation in temperature (warm to hot summers and cold winters). They tend to occur in central and eastern parts of the three northern-tier continents (North America, Europe, and Asia), typically in the middle latitudes (40 to 55 or 60 degrees north), often within large landmasses, where prevailing winds blow overland bringing some precipitation, and temperatures are not moderated by oceans. Continental climates occur mostly in the Northern Hemisphere due to the large landmasses found there. Most of northeastern China, eastern and southeastern Europe, much of Russia south of the Arctic Circle, central and southeastern Canada, and the central and northeastern United States have this type of climate. Continentality is a measure of the degree to which a region experiences this type of climate. In continental climates, precipitation tends to be moderate in amount, concentrated mostly in the warmer months. Only a few areas—in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silt
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension (chemistry), suspension with water. Silt usually has a floury feel when dry, and lacks Plasticity (physics), plasticity when wet. Silt can also be felt by the tongue as granular when placed on the front teeth (even when mixed with clay particles). Silt is a common material, making up 45% of average modern mud. It is found in many river deltas and as wind-deposited accumulations, particularly in central Asia, north China, and North America. It is produced in both very hot climates (through such processes as collisions of quartz grains in dust storms) and very cold climates (through such processes as glacial grinding of quartz grains.) Loess is soil rich in silt which makes up some of the most fertile agricultural land on Earth. However, silt is very vulnerable to erosion, and it has poo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glaciolacustrine Deposits
Sediments deposited into lakes that have come from glaciers are called glaciolacustrine deposits. In some European geological traditions, the term limnoglacial is used. These lakes include ice margin lakes or other types formed from glacial erosion or deposition. Sediments in the bedload and suspended load are carried into lakes and deposited. The bedload is deposited at the lake margin while the suspended load is deposited all over the lake bed. Glaciolacustrine deposits commonly form varves, which are annually deposited layers of silt and clay, where silt is deposited during the summer, and clay during the winter. Bedload deposits Sediments carried in the bedload of a stream, mostly sands and gravels, are deposited in deltas that form at the edges of lakes. These deposits will only be found near the edges of the lake. Suspended deposits Sediments that are carried in the suspended load of a stream, commonly silts and clays, are transported into the lake in suspension or by cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Till
image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is diagnostic of till. image:Glacial till exposed in roadcut-750px.jpg, Glacial till with tufts of grass Till or glacial till is unsorted glacier, glacial sediment. Till is derived from the erosion and entrainment of material by the moving ice of a glacier. It is deposited some distance down-ice to form terminal, lateral, medial and ground moraines. Till is classified into primary deposits, laid down directly by glaciers, and secondary deposits, reworked by fluvial transport and other processes. Description Till is a form of '' glacial drift'', which is rock material transported by a glacier and deposited directly from the ice or from running water emerging from the ice. It is distinguished from other forms of drift in that it is de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latvia
Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to the southeast, and shares a Maritime boundary, maritime border with Sweden to the west. Latvia covers an area of , with a population of 1.9million. The country has a Temperate climate, temperate seasonal climate. Its capital and List of cities and towns in Latvia, largest city is Riga. Latvians, who are the titular nation and comprise 65.5% of the country's population, belong to the ethnolinguistic group of the Balts and speak Latvian language, Latvian. Russians in Latvia, Russians are the most prominent minority in the country, at almost a quarter of the population; 37.7% of the population speak Russian language, Russian as their native tongue. After centuries of State of the Teutonic Order, Teutonic, Swedish Livonia, Swedish, Inflanty Voi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
