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88-494: The tabia stretches down south of the main road towards Rubaksa, which is a wider area with several springs and traditional irrigation. The highest peak is Gumawta (2815 m a.s.l.) on the Tsatsen plateau and the lowest place Rubaksa (1920 m a.s.l.). From the higher to the lower locations, the following geological formations are present: The main geomorphic units, with corresponding soil types are: As there are no permanent rivers,

176-414: A concept of physiographic regions while a conflicting trend among geographers was to equate physiography with "pure morphology", separated from its geological heritage. In the period following World War II, the emergence of process, climatic, and quantitative studies led to a preference by many earth scientists for the term "geomorphology" in order to suggest an analytical approach to landscapes rather than

264-491: A decline in the popularity of climatic geomorphology in the late 20th century. Stoddart criticized climatic geomorphology for applying supposedly "trivial" methodologies in establishing landform differences between morphoclimatic zones, being linked to Davisian geomorphology and by allegedly neglecting the fact that physical laws governing processes are the same across the globe. In addition some conceptions of climatic geomorphology, like that which holds that chemical weathering

352-438: A descriptive one. During the age of New Imperialism in the late 19th century European explorers and scientists traveled across the globe bringing descriptions of landscapes and landforms. As geographical knowledge increased over time these observations were systematized in a search for regional patterns. Climate emerged thus as prime factor for explaining landform distribution at a grand scale. The rise of climatic geomorphology

440-590: A dry-climate area unsuitable at that time for the growth of bamboo. The invention of thermometers and barometers during the Scientific Revolution allowed for systematic recordkeeping, that began as early as 1640–1642 in England. Early climate researchers include Edmund Halley , who published a map of the trade winds in 1686 after a voyage to the southern hemisphere. Benjamin Franklin (1706–1790) first mapped

528-405: A few administrative offices and some small shops. The villages close to Hagere Selam (Dingilet and Harena) have established a new settlement, at the margin of Hagere Selam, where the inhabitants benefit from the proximity of the town. The main other populated places in the tabia are: Most inhabitants are Orthodox Christians . The following churches are located in the tabia : In Megesta, there

616-411: A few decades to as long as millions of years. The climate system receives nearly all of its energy from the sun. The climate system also gives off energy to outer space . The balance of incoming and outgoing energy, and the passage of the energy through the climate system, determines Earth's energy budget . When the incoming energy is greater than the outgoing energy, earth's energy budget is positive and

704-558: A fictional dialogue where the immortal Magu explained that the territory of the East China Sea was once a land filled with mulberry trees . The term geomorphology seems to have been first used by Laumann in an 1858 work written in German. Keith Tinkler has suggested that the word came into general use in English, German and French after John Wesley Powell and W. J. McGee used it during

792-478: A generalized, overall description of the atmosphere or ocean which can be used to characterize the factors which effect the global climate system. El Niño–Southern Oscillation (ENSO) is a coupled ocean-atmosphere phenomenon in the Pacific Ocean responsible for much of the global variability of temperature, and has a cycle between two and seven years. The North Atlantic oscillation is a mode of variability that

880-413: A global network of thermometers , to prehistoric ice extracted from glaciers . As measuring technology changes over time, records of data often cannot be compared directly. As cities are generally warmer than the areas surrounding, urbanization has made it necessary to constantly correct data for this urban heat island effect. Climate models use quantitative methods to simulate the interactions of

968-697: A good place for resting and chatting with the local people. Most renown in the tabia are The facilities are very basic. One may be invited to spend the night in a rural homestead or ask permission to pitch a tent. Hotels are available in Hagere Selam and Mekelle . For more details on environment, agriculture, rural sociology, hydrology, ecology, culture, etc., see the overall page on the Dogu’a Tembien district. Geomorphic Geomorphology (from Ancient Greek : γῆ , gê , 'earth'; μορφή , morphḗ , 'form'; and λόγος , lógos , 'study')

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1056-435: A mountain belt to promote further erosion as mass is removed from the chain and the belt uplifts. Long-term plate tectonic dynamics give rise to orogenic belts , large mountain chains with typical lifetimes of many tens of millions of years, which form focal points for high rates of fluvial and hillslope processes and thus long-term sediment production. Features of deeper mantle dynamics such as plumes and delamination of

1144-411: A period of at least 30 years. Climate concerns the atmospheric condition during an extended to indefinite period of time; weather is the condition of the atmosphere during a relative brief period of time. The main topics of research are the study of climate variability , mechanisms of climate changes and modern climate change . This topic of study is regarded as part of the atmospheric sciences and

1232-452: A short period of time, making them extremely important entities in the high latitudes and meaning that they set the conditions in the headwaters of mountain-born streams; glaciology therefore is important in geomorphology. Climatology Climatology (from Greek κλίμα , klima , "slope"; and -λογία , -logia ) or climate science is the scientific study of Earth's climate , typically defined as weather conditions averaged over

1320-491: A subdivision of physical geography , which is one of the Earth sciences . Climatology includes some aspects of oceanography and biogeochemistry . The main methods employed by climatologists are the analysis of observations and modelling of the physical processes that determine climate. Short term weather forecasting can be interpreted in terms of knowledge of longer-term phenomena of climate, for instance climatic cycles such as

1408-485: A valley causes abrasion and plucking of the underlying rock . Abrasion produces fine sediment, termed glacial flour . The debris transported by the glacier, when the glacier recedes, is termed a moraine . Glacial erosion is responsible for U-shaped valleys, as opposed to the V-shaped valleys of fluvial origin. The way glacial processes interact with other landscape elements, particularly hillslope and fluvial processes,

1496-643: A very brief outline of some of the major figures and events in its development. The study of landforms and the evolution of the Earth's surface can be dated back to scholars of Classical Greece . In the 5th century BC, Greek historian Herodotus argued from observations of soils that the Nile delta was actively growing into the Mediterranean Sea , and estimated its age. In the 4th century BC, Greek philosopher Aristotle speculated that due to sediment transport into

1584-409: A year. Another major variable of climate is continentality: the distance to major water bodies such as oceans . Oceans act as a moderating factor, so that land close to it has typically less difference of temperature between winter and summer than areas further from it. The atmosphere interacts with other parts of the climate system , with winds generating ocean currents that transport heat around

1672-540: Is a strong story about the Queen of Sheba who was transformed in a snake; the track of the snake is represented by a line of trees up to now. In the northern part of Harena, called Argak'a, there is a large rock of more than 50 m - the story goes that a certain Ilias transported it up to there. The history of the tabia is strongly confounded with the history of Tembien . The main road Mekelle – Hagere Selam – Abiy Addi runs at

1760-603: Is an important aspect of Plio-Pleistocene landscape evolution and its sedimentary record in many high mountain environments. Environments that have been relatively recently glaciated but are no longer may still show elevated landscape change rates compared to those that have never been glaciated. Nonglacial geomorphic processes which nevertheless have been conditioned by past glaciation are termed paraglacial processes. This concept contrasts with periglacial processes, which are directly driven by formation or melting of ice or frost. Soil , regolith , and rock move downslope under

1848-699: Is extremely important in sedimentology . Weathering is the chemical and physical disruption of earth materials in place on exposure to atmospheric or near surface agents, and is typically studied by soil scientists and environmental chemists , but is an essential component of geomorphology because it is what provides the material that can be moved in the first place. Civil and environmental engineers are concerned with erosion and sediment transport, especially related to canals , slope stability (and natural hazards ), water quality , coastal environmental management, transport of contaminants, and stream restoration . Glaciers can cause extensive erosion and deposition in

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1936-630: Is mainly contained to the lower atmosphere, the troposphere . The layer of atmosphere above, the stratosphere is also capable of creating its own variability, most importantly the Madden–Julian oscillation (MJO), which has a cycle of approximately 30 to 60 days. The Interdecadal Pacific oscillation can create changes in the Pacific Ocean and lower atmosphere on decadal time scales. Climate change occurs when changes of Earth's climate system result in new weather patterns that remain for an extended period of time. This duration of time can be as brief as

2024-611: Is more rapid in tropical climates than in cold climates proved to not be straightforwardly true. Geomorphology was started to be put on a solid quantitative footing in the middle of the 20th century. Following the early work of Grove Karl Gilbert around the turn of the 20th century, a group of mainly American natural scientists, geologists and hydraulic engineers including William Walden Rubey , Ralph Alger Bagnold , Hans Albert Einstein , Frank Ahnert , John Hack , Luna Leopold , A. Shields , Thomas Maddock , Arthur Strahler , Stanley Schumm , and Ronald Shreve began to research

2112-444: Is probably of profound importance for the terrestrial geomorphic system as a whole. Biology can influence very many geomorphic processes, ranging from biogeochemical processes controlling chemical weathering , to the influence of mechanical processes like burrowing and tree throw on soil development, to even controlling global erosion rates through modulation of climate through carbon dioxide balance. Terrestrial landscapes in which

2200-415: Is since the 1990s no longer accepted by mainstream scholarship as a basis for geomorphological studies. Albeit having its importance diminished, climatic geomorphology continues to exist as field of study producing relevant research. More recently concerns over global warming have led to a renewed interest in the field. Despite considerable criticism, the cycle of erosion model has remained part of

2288-471: Is sometimes modeled as a stochastic process but this is generally accepted as an approximation to processes that are otherwise too complicated to analyze. The collection of a long record of climate variables is essential for the study of climate. Climatology deals with the aggregate data that meteorologists have recorded. Scientists use both direct and indirect observations of the climate, from Earth observing satellites and scientific instrumentation such as

2376-491: Is sometimes termed hydroclimatology, in particular when studying the effects of climate change on the water cycle. The study of contemporary climates incorporates meteorological data accumulated over many years, such as records of rainfall, temperature and atmospheric composition. Knowledge of the atmosphere and its dynamics is also embodied in models , either statistical or mathematical , which help by integrating different observations and testing how well they match. Modeling

2464-705: Is the scientific study of the origin and evolution of topographic and bathymetric features generated by physical, chemical or biological processes operating at or near Earth's surface . Geomorphologists seek to understand why landscapes look the way they do, to understand landform and terrain history and dynamics and to predict changes through a combination of field observations, physical experiments and numerical modeling . Geomorphologists work within disciplines such as physical geography , geology , geodesy , engineering geology , archaeology , climatology , and geotechnical engineering . This broad base of interests contributes to many research styles and interests within

2552-435: Is the study of climate as related to human history and is thus concerned mainly with the last few thousand years. Boundary-layer climatology concerns exchanges in water, energy and momentum near surfaces. Further identified subtopics are physical climatology, dynamic climatology, tornado climatology , regional climatology, bioclimatology , and synoptic climatology. The study of the hydrological cycle over long time scales

2640-441: Is used for understanding past, present and potential future climates. Climate research is made difficult by the large scale, long time periods, and complex processes which govern climate. Climate is governed by physical principles which can be expressed as differential equations . These equations are coupled and nonlinear, so that approximate solutions are obtained by using numerical methods to create global climate models . Climate

2728-584: The Bulletin of the Geological Society of America , and received only few citations prior to 2000 (they are examples of "sleeping beauties" ) when a marked increase in quantitative geomorphology research occurred. Quantitative geomorphology can involve fluid dynamics and solid mechanics , geomorphometry , laboratory studies, field measurements, theoretical work, and full landscape evolution modeling . These approaches are used to understand weathering and

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2816-706: The El Niño–Southern Oscillation (ENSO), the Madden–Julian oscillation (MJO), the North Atlantic oscillation (NAO), the Arctic oscillation (AO), the Pacific decadal oscillation (PDO), and the Interdecadal Pacific Oscillation (IPO). Climate models are used for a variety of purposes from studying the dynamics of the weather and climate system to predictions of future climate. The Greeks began

2904-517: The Köppen climate classification , was developed during the late nineteenth century and is based on vegetation. It uses monthly data concerning temperature and precipitation . There are different types of variability: recurring patterns of temperature or other climate variables. They are quantified with different indices. Much in the way the Dow Jones Industrial Average , which is based on

2992-482: The climate system , such as the widespread melt of glaciers , sea level rise and shifts of flora and fauna. In contrast to meteorology , which emphasises short term weather systems lasting no more than a few weeks, climatology studies the frequency and trends of those systems. It studies the periodicity of weather events over years to millennia, as well as changes of long-term average weather patterns in relation to atmospheric conditions. Climatologists study both

3080-455: The tabia fit for tourism. The high variability of geological formations and the rugged topography invites for geological and geographic tourism or "geotourism". Geosites in the tabia include: Trekking routes have been established in this tabia . The tracks are not marked on the ground but can be followed using downloaded .GPX files. In the main villages, there are traditional beer houses ( Inda Siwa ), often in unique settings, which are

3168-667: The Earth illustrate this intersection of surface and subsurface action. Mountain belts are uplifted due to geologic processes. Denudation of these high uplifted regions produces sediment that is transported and deposited elsewhere within the landscape or off the coast. On progressively smaller scales, similar ideas apply, where individual landforms evolve in response to the balance of additive processes (uplift and deposition) and subtractive processes ( subsidence and erosion ). Often, these processes directly affect each other: ice sheets, water, and sediment are all loads that change topography through flexural isostasy . Topography can modify

3256-425: The Earth's land surface areas). Topics that climatologists study comprise three main categories: climate variability , mechanisms of climatic change, and modern changes of climate. Various factors affect the average state of the atmosphere at a particular location. For instance, midlatitudes will have a pronounced seasonal cycle of temperature whereas tropical regions show little variation of temperature over

3344-655: The Earth, biological processes such as burrowing or tree throw may play important roles in setting the rates of some hillslope processes. Both volcanic (eruptive) and plutonic (intrusive) igneous processes can have important impacts on geomorphology. The action of volcanoes tends to rejuvenize landscapes, covering the old land surface with lava and tephra , releasing pyroclastic material and forcing rivers through new paths. The cones built by eruptions also build substantial new topography, which can be acted upon by other surface processes. Plutonic rocks intruding then solidifying at depth can cause both uplift or subsidence of

3432-699: The Earth. Any unbalance results in a change of the average temperature of the Earth. Most climate models include the radiative effects of greenhouse gases such as carbon dioxide . These models predict a trend of increase of surface temperatures , as well as a more rapid increase of temperature at higher latitudes. Models can range from relatively simple to complex: Additionally, they are available with different resolutions ranging from >100 km to 1 km. High resolutions in global climate models are computational very demanding and only few global datasets exists. Examples are ICON or mechanistically downscaled data such as CHELSA (Climatologies at high resolution for

3520-516: The International Geological Conference of 1891. John Edward Marr in his The Scientific Study of Scenery considered his book as, 'an Introductory Treatise on Geomorphology, a subject which has sprung from the union of Geology and Geography'. An early popular geomorphic model was the geographical cycle or cycle of erosion model of broad-scale landscape evolution developed by William Morris Davis between 1884 and 1899. It

3608-400: The atmosphere, oceans, land surface, and ice. They are used for a variety of purposes from study of the dynamics of the weather and climate system to projections of future climate. All climate models balance, or very nearly balance, incoming energy as short wave (including visible) electromagnetic radiation to the Earth with outgoing energy as long wave (infrared) electromagnetic radiation from

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3696-441: The availability of sediment itself and on the river's discharge . Rivers are also capable of eroding into rock and forming new sediment, both from their own beds and also by coupling to the surrounding hillslopes. In this way, rivers are thought of as setting the base level for large-scale landscape evolution in nonglacial environments. Rivers are key links in the connectivity of different landscape elements. As rivers flow across

3784-523: The centuries. He inferred that the land was reshaped and formed by soil erosion of the mountains and by deposition of silt , after observing strange natural erosions of the Taihang Mountains and the Yandang Mountain near Wenzhou . Furthermore, he promoted the theory of gradual climate change over centuries of time once ancient petrified bamboos were found to be preserved underground in

3872-552: The climate system is warming. If more energy goes out, the energy budget is negative and earth experiences cooling. Climate change also influences the average sea level . Modern climate change is caused largely by the human emissions of greenhouse gas from the burning of fossil fuel which increases global mean surface temperatures . Increasing temperature is only one aspect of modern climate change, which also includes observed changes of precipitation , storm tracks and cloudiness. Warmer temperatures are causing further changes of

3960-520: The course of the Gulf Stream for use in sending mail from North America to Europe. Francis Galton (1822–1911) invented the term anticyclone . Helmut Landsberg (1906–1985) fostered the use of statistical analysis in climatology. During the early 20th century, climatology mostly emphasized the description of regional climates. This descriptive climatology was mainly an applied science, giving farmers and other interested people statistics about what

4048-457: The cycle over. In the decades following Davis's development of this idea, many of those studying geomorphology sought to fit their findings into this framework, known today as "Davisian". Davis's ideas are of historical importance, but have been largely superseded today, mainly due to their lack of predictive power and qualitative nature. In the 1920s, Walther Penck developed an alternative model to Davis's. Penck thought that landform evolution

4136-482: The decades that followed, and while the history of climate change science started earlier, climate change only became one of the main topics of study for climatologists during the 1970s and afterward. Various subtopics of climatology study different aspects of climate. There are different categorizations of the sub-topics of climatology. The American Meteorological Society for instance identifies descriptive climatology, scientific climatology and applied climatology as

4224-565: The dry, northern climate zone of Yanzhou , which is now modern day Yan'an , Shaanxi province. Previous Chinese authors also presented ideas about changing landforms. Scholar-official Du Yu (222–285) of the Western Jin dynasty predicted that two monumental stelae recording his achievements, one buried at the foot of a mountain and the other erected at the top, would eventually change their relative positions over time as would hills and valleys. Daoist alchemist Ge Hong (284–364) created

4312-413: The early 1900s, the study of regional-scale geomorphology was termed "physiography". Physiography later was considered to be a contraction of " physi cal" and "ge ography ", and therefore synonymous with physical geography , and the concept became embroiled in controversy surrounding the appropriate concerns of that discipline. Some geomorphologists held to a geological basis for physiography and emphasized

4400-491: The early 19th century, authors – especially in Europe – had tended to attribute the form of landscapes to local climate , and in particular to the specific effects of glaciation and periglacial processes. In contrast, both Davis and Penck were seeking to emphasize the importance of evolution of landscapes through time and the generality of the Earth's surface processes across different landscapes under different conditions. During

4488-430: The field of geomorphology encompasses a very wide range of different approaches and interests. Modern researchers aim to draw out quantitative "laws" that govern Earth surface processes, but equally, recognize the uniqueness of each landscape and environment in which these processes operate. Particularly important realizations in contemporary geomorphology include: According to Karna Lidmar-Bergström , regional geography

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4576-451: The field. Earth 's surface is modified by a combination of surface processes that shape landscapes, and geologic processes that cause tectonic uplift and subsidence , and shape the coastal geography . Surface processes comprise the action of water, wind, ice, wildfire , and life on the surface of the Earth, along with chemical reactions that form soils and alter material properties, the stability and rate of change of topography under

4664-590: The force of gravity via creep , slides , flows, topples, and falls. Such mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth , Mars , Venus , Titan and Iapetus . Ongoing hillslope processes can change the topology of the hillslope surface, which in turn can change the rates of those processes. Hillslopes that steepen up to certain critical thresholds are capable of shedding extremely large volumes of material very quickly, making hillslope processes an extremely important element of landscapes in tectonically active areas. On

4752-401: The force of gravity , and other factors, such as (in the very recent past) human alteration of the landscape. Many of these factors are strongly mediated by climate . Geologic processes include the uplift of mountain ranges , the growth of volcanoes , isostatic changes in land surface elevation (sometimes in response to surface processes), and the formation of deep sedimentary basins where

4840-494: The form of landscape elements such as rivers and hillslopes by taking systematic, direct, quantitative measurements of aspects of them and investigating the scaling of these measurements. These methods began to allow prediction of the past and future behavior of landscapes from present observations, and were later to develop into the modern trend of a highly quantitative approach to geomorphic problems. Many groundbreaking and widely cited early geomorphology studies appeared in

4928-846: The formal study of climate; in fact, the word "climate" is derived from the Greek word klima , meaning "slope", referring to the slope or inclination of the Earth's axis. Arguably the most influential classic text concerning climate was On Airs, Water and Places written by Hippocrates about 400 BCE . This work commented on the effect of climate on human health and cultural differences between Asia and Europe. This idea that climate controls which populations excel depending on their climate, or climatic determinism , remained influential throughout history. Chinese scientist Shen Kuo (1031–1095) inferred that climates naturally shifted over an enormous span of time, after observing petrified bamboos found underground near Yanzhou (modern Yan'an , Shaanxi province),

5016-663: The formation of soils , sediment transport , landscape change, and the interactions between climate, tectonics, erosion, and deposition. In Sweden Filip Hjulström 's doctoral thesis, "The River Fyris" (1935), contained one of the first quantitative studies of geomorphological processes ever published. His students followed in the same vein, making quantitative studies of mass transport ( Anders Rapp ), fluvial transport ( Åke Sundborg ), delta deposition ( Valter Axelsson ), and coastal processes ( John O. Norrman ). This developed into "the Uppsala School of Physical Geography ". Today,

5104-481: The future. Some refer to this type of forecasting as pattern recognition, which remains a useful method of estimating rainfall over data voids such as oceans using knowledge of how satellite imagery relates to precipitation rates over land, as well as the forecasting of precipitation amounts and distribution of the future. A variation of this theme, used for medium range forecasting, is known as teleconnections , when systems in other locations are used to help determine

5192-427: The geologic and atmospheric history of those planets but also extends geomorphological study of the Earth. Planetary geomorphologists often use Earth analogues to aid in their study of surfaces of other planets. Other than some notable exceptions in antiquity, geomorphology is a relatively young science, growing along with interest in other aspects of the earth sciences in the mid-19th century. This section provides

5280-555: The globe. Classification is an important method of simplifying complicated processes. Different climate classifications have been developed over the centuries, with the first ones in Ancient Greece . How climates are classified depends on what the application is. A wind energy producer will require different information (wind) in a classification than someone more interested in agriculture, for whom precipitation and temperature are more important. The most widely used classification,

5368-677: The landscape, they generally increase in size, merging with other rivers. The network of rivers thus formed is a drainage system . These systems take on four general patterns: dendritic, radial, rectangular, and trellis. Dendritic happens to be the most common, occurring when the underlying stratum is stable (without faulting). Drainage systems have four primary components: drainage basin , alluvial valley, delta plain, and receiving basin. Some geomorphic examples of fluvial landforms are alluvial fans , oxbow lakes , and fluvial terraces . Glaciers , while geographically restricted, are effective agents of landscape change. The gradual movement of ice down

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5456-474: The landscape. Fluvial geomorphologists focus on rivers , how they transport sediment , migrate across the landscape , cut into bedrock , respond to environmental and tectonic changes, and interact with humans. Soils geomorphologists investigate soil profiles and chemistry to learn about the history of a particular landscape and understand how climate, biota, and rock interact. Other geomorphologists study how hillslopes form and change. Still others investigate

5544-691: The local climate, for example through orographic precipitation , which in turn modifies the topography by changing the hydrologic regime in which it evolves. Many geomorphologists are particularly interested in the potential for feedbacks between climate and tectonics , mediated by geomorphic processes. In addition to these broad-scale questions, geomorphologists address issues that are more specific or more local. Glacial geomorphologists investigate glacial deposits such as moraines , eskers , and proglacial lakes , as well as glacial erosional features, to build chronologies of both small glaciers and large ice sheets and understand their motions and effects upon

5632-465: The lower lithosphere have also been hypothesised to play important roles in the long term (> million year), large scale (thousands of km) evolution of the Earth's topography (see dynamic topography ). Both can promote surface uplift through isostasy as hotter, less dense, mantle rocks displace cooler, denser, mantle rocks at depth in the Earth. Marine processes are those associated with the action of waves, marine currents and seepage of fluids through

5720-508: The mid-20th century considered both un-innovative and dubious. Early climatic geomorphology developed primarily in continental Europe while in the English-speaking world the tendency was not explicit until L.C. Peltier's 1950 publication on a periglacial cycle of erosion. Climatic geomorphology was criticized in a 1969 review article by process geomorphologist D.R. Stoddart . The criticism by Stoddart proved "devastating" sparking

5808-406: The nature of climates – local, regional or global – and the natural or human-induced factors that cause climates to change. Climatology considers the past and can help predict future climate change . Phenomena of climatological interest include the atmospheric boundary layer , circulation patterns , heat transfer ( radiative , convective and latent ), interactions between the atmosphere and

5896-413: The normal weather was and how great chances were of extreme events. To do this, climatologists had to define a climate normal , or an average of weather and weather extremes over a period of typically 30 years. While scientists knew of past climate change such as the ice ages , the concept of climate as changing only very gradually was useful for descriptive climatology. This started to change during

5984-486: The north and west of the tabia . Inhabitants mostly move on foot to Hagere Selam from where they can travel further. A rural access road links Hagere Selam to the main villages of Mika’el Abiy. Almost all children of the tabia are schooled, though in some schools there is lack of classrooms, directly related to the large intake in primary schools over the last decades. Schools in the tabia include Selam Seret school. Its mountainous nature and proximity to Mekelle makes

6072-403: The oceans and land surface (particularly vegetation, land use and topography ), and the chemical and physical composition of the atmosphere. A relative difficult method of forecast, the analog technique requires remembering a previous weather event which is expected to be mimicked by an upcoming event. What makes it a difficult technique is that there is rarely a perfect analog for an event of

6160-857: The physics of landscapes. Geomorphologists may rely on geochronology , using dating methods to measure the rate of changes to the surface. Terrain measurement techniques are vital to quantitatively describe the form of the Earth's surface, and include differential GPS , remotely sensed digital terrain models and laser scanning , to quantify, study, and to generate illustrations and maps. Practical applications of geomorphology include hazard assessment (such as landslide prediction and mitigation ), river control and stream restoration , and coastal protection. Planetary geomorphology studies landforms on other terrestrial planets such as Mars. Indications of effects of wind , fluvial , glacial , mass wasting , meteor impact , tectonics and volcanic processes are studied. This effort not only helps better understand

6248-455: The presence of springs is of utmost importance for the local people. The following are the main springs in the tabia: The population lives essentially from crop farming, supplemented with off-season work in nearby towns. The land is dominated by farmlands which are clearly demarcated and are cropped every year. Hence the agricultural system is a permanent upland farming system, and the population are not nomads. The tabia centre Megesta holds

6336-423: The relationships between ecology and geomorphology. Because geomorphology is defined to comprise everything related to the surface of the Earth and its modification, it is a broad field with many facets. Geomorphologists use a wide range of techniques in their work. These may include fieldwork and field data collection, the interpretation of remotely sensed data, geochemical analyses, and the numerical modelling of

6424-487: The role of biology in mediating surface processes can be definitively excluded are extremely rare, but may hold important information for understanding the geomorphology of other planets, such as Mars . Rivers and streams are not only conduits of water, but also of sediment . The water, as it flows over the channel bed, is able to mobilize sediment and transport it downstream, either as bed load , suspended load or dissolved load . The rate of sediment transport depends on

6512-760: The science of historical geology . While acknowledging its shortcomings, modern geomorphologists Andrew Goudie and Karna Lidmar-Bergström have praised it for its elegance and pedagogical value respectively. Geomorphically relevant processes generally fall into (1) the production of regolith by weathering and erosion , (2) the transport of that material, and (3) its eventual deposition . Primary surface processes responsible for most topographic features include wind , waves , chemical dissolution , mass wasting , groundwater movement, surface water flow, glacial action , tectonism , and volcanism . Other more exotic geomorphic processes might include periglacial (freeze-thaw) processes, salt-mediated action, changes to

6600-409: The science of geomorphology. The model or theory has never been proved wrong, but neither has it been proven. The inherent difficulties of the model have instead made geomorphological research to advance along other lines. In contrast to its disputed status in geomorphology, the cycle of erosion model is a common approach used to establish denudation chronologies , and is thus an important concept in

6688-523: The sea, eventually those seas would fill while the land lowered. He claimed that this would mean that land and water would eventually swap places, whereupon the process would begin again in an endless cycle. The Encyclopedia of the Brethren of Purity published in Arabic at Basra during the 10th century also discussed the cyclical changing positions of land and sea with rocks breaking down and being washed into

6776-519: The sea, their sediment eventually rising to form new continents. The medieval Persian Muslim scholar Abū Rayhān al-Bīrūnī (973–1048), after observing rock formations at the mouths of rivers, hypothesized that the Indian Ocean once covered all of India . In his De Natura Fossilium of 1546, German metallurgist and mineralogist Georgius Agricola (1494–1555) wrote about erosion and natural weathering . Another early theory of geomorphology

6864-704: The seabed caused by marine currents, seepage of fluids through the seafloor or extraterrestrial impact. Aeolian processes pertain to the activity of the winds and more specifically, to the winds' ability to shape the surface of the Earth . Winds may erode, transport, and deposit materials, and are effective agents in regions with sparse vegetation and a large supply of fine, unconsolidated sediments . Although water and mass flow tend to mobilize more material than wind in most environments, aeolian processes are important in arid environments such as deserts . The interaction of living organisms with landforms, or biogeomorphologic processes , can be of many different forms, and

6952-459: The seafloor. Mass wasting and submarine landsliding are also important processes for some aspects of marine geomorphology. Because ocean basins are the ultimate sinks for a large fraction of terrestrial sediments, depositional processes and their related forms (e.g., sediment fans, deltas ) are particularly important as elements of marine geomorphology. There is a considerable overlap between geomorphology and other fields. Deposition of material

7040-434: The stock prices of 30 companies, is used to represent the fluctuations of stock prices in general, climate indices are used to represent the essential elements of climate. Climate indices are generally devised with the twin objectives of simplicity and completeness, and each index typically represents the status and timing of the climate factor it represents. By their very nature, indices are simple, and combine many details into

7128-407: The surface of the Earth drops and is filled with material eroded from other parts of the landscape. The Earth's surface and its topography therefore are an intersection of climatic , hydrologic , and biologic action with geologic processes, or alternatively stated, the intersection of the Earth's lithosphere with its hydrosphere , atmosphere , and biosphere . The broad-scale topographies of

7216-596: The surface, depending on whether the new material is denser or less dense than the rock it displaces. Tectonic effects on geomorphology can range from scales of millions of years to minutes or less. The effects of tectonics on landscape are heavily dependent on the nature of the underlying bedrock fabric that more or less controls what kind of local morphology tectonics can shape. Earthquakes can, in terms of minutes, submerge large areas of land forming new wetlands. Isostatic rebound can account for significant changes over hundreds to thousands of years, and allows erosion of

7304-511: The three subcategories of climatology, a categorization based on the complexity and the purpose of the research. Applied climatologists apply their expertise to different industries such as manufacturing and agriculture . Paleoclimatology is the attempt to reconstruct and understand past climates by examining records such as ice cores and tree rings ( dendroclimatology ). Paleotempestology uses these same records to help determine hurricane frequency over millennia. Historical climatology

7392-434: Was German, and during his lifetime his ideas were at times rejected vigorously by the English-speaking geomorphology community. His early death, Davis' dislike for his work, and his at-times-confusing writing style likely all contributed to this rejection. Both Davis and Penck were trying to place the study of the evolution of the Earth's surface on a more generalized, globally relevant footing than it had been previously. In

7480-444: Was an elaboration of the uniformitarianism theory that had first been proposed by James Hutton (1726–1797). With regard to valley forms, for example, uniformitarianism posited a sequence in which a river runs through a flat terrain, gradually carving an increasingly deep valley, until the side valleys eventually erode, flattening the terrain again, though at a lower elevation. It was thought that tectonic uplift could then start

7568-416: Was better described as an alternation between ongoing processes of uplift and denudation, as opposed to Davis's model of a single uplift followed by decay. He also emphasised that in many landscapes slope evolution occurs by backwearing of rocks, not by Davisian-style surface lowering, and his science tended to emphasise surface process over understanding in detail the surface history of a given locality. Penck

7656-500: Was devised by Song dynasty Chinese scientist and statesman Shen Kuo (1031–1095). This was based on his observation of marine fossil shells in a geological stratum of a mountain hundreds of miles from the Pacific Ocean . Noticing bivalve shells running in a horizontal span along the cut section of a cliffside, he theorized that the cliff was once the pre-historic location of a seashore that had shifted hundreds of miles over

7744-402: Was foreshadowed by the work of Wladimir Köppen , Vasily Dokuchaev and Andreas Schimper . William Morris Davis , the leading geomorphologist of his time, recognized the role of climate by complementing his "normal" temperate climate cycle of erosion with arid and glacial ones. Nevertheless, interest in climatic geomorphology was also a reaction against Davisian geomorphology that was by

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