1.
Climate
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Climate is the statistics of weather, usually over a 30-year interval. Climate differs from weather, in that weather only describes the conditions of these variables in a given region. A regions climate is generated by the system, which has five components, atmosphere, hydrosphere, cryosphere, lithosphere. The climate of a location is affected by its latitude, terrain, climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was the Köppen climate classification, the Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region. Paleoclimatology is the study of ancient climates, Climate models are mathematical models of past, present and future climates. Climate change may occur long and short timescales from a variety of factors. For example, a 3°C change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km in latitude or 500 m in elevation, therefore, species are expected to move upwards in elevation or towards the poles in latitude in response to shifting climate zones. Climate is commonly defined as the weather averaged over a long period, the standard averaging period is 30 years, but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations, the classical period is 30 years, as defined by the World Meteorological Organization. These quantities are most often surface variables such as temperature, precipitation, Climate in a wider sense is the state, including a statistical description, of the climate system. The World Meteorological Organization describes climate normals as reference points used by climatologists to compare current climatological trends to that of the past or what is considered normal, a Normal is defined as the arithmetic average of a climate element over a 30-year period. A30 year period is used, as it is enough to filter out any interannual variation or anomalies. The WMO originated from the International Meteorological Organization which set up a commission for climatology in 1929. At its 1934 Wiesbaden meeting the commission designated the thirty-year period from 1901 to 1930 as the reference time frame for climatological standard normals. In 1982 the WMO agreed to update climate normals, and in these were completed on the basis of climate data from 1 January 1961 to 31 December 1990. The difference between climate and weather is usefully summarized by the popular phrase Climate is what you expect, weather is what you get. Over historical time spans there are a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water and these change only over periods of millions of years due to processes such as plate tectonics
2.
Evapotranspiration
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Evapotranspiration is the sum of evaporation and plant transpiration from the Earths land and ocean surface to the atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, transpiration accounts for the movement of water within a plant and the subsequent loss of water as vapor through stomata in its leaves. Evapotranspiration is an important part of the water cycle, an element that contributes to evapotranspiration can be called an evapotranspirator. It is a reflection of the energy available to evaporate water, actual evapotranspiration is said to equal reference evapotranspiration when there is ample water. Some US states utilize a full cover alfalfa reference crop that is 0.5 m in height, rather than the green grass reference. Evapotranspiration is a significant water loss from drainage basins, types of vegetation and land use significantly affect evapotranspiration, and therefore the amount of water leaving a drainage basin. Because water transpired through leaves comes from the roots, plants with deep reaching roots can more constantly transpire water, herbaceous plants generally transpire less than woody plants because they usually have less extensive foliage. Conifer forests tend to have higher rates of evapotranspiration than deciduous forests, particularly in the dormant and this is primarily due to the enhanced amount of precipitation intercepted and evaporated by conifer foliage during these periods. Factors that affect evapotranspiration include the growth stage or level of maturity, percentage of soil cover, solar radiation, humidity, temperature. Isotope measurements indicate transpiration is the component of evapotranspiration. Through evapotranspiration, forests reduce water yield, except in unique ecosystems called cloud forests, trees in cloud forests collect the liquid water in fog or low clouds onto their surface, which drips down to the ground. These trees still contribute to evapotranspiration, but often more water than they evaporate or transpire. In areas that are not irrigated, actual evapotranspiration is usually no greater than precipitation and it will usually be less because some water will be lost due to percolation or surface runoff. An exception is areas with water tables, where capillary action can cause water from the groundwater to rise through the soil matrix to the surface. If potential evapotranspiration is greater than precipitation, then soil will dry out. Evapotranspiration can never be greater than PET, but can be if there is not enough water to be evaporated or plants are unable to transpire readily. Evapotranspiration can be measured or estimated using several methods, pan evaporation data can be used to estimate lake evaporation, but transpiration and evaporation of intercepted rain on vegetation are unknown. There are three approaches to estimate evapotranspiration indirectly
3.
Desert climate
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An area that features this climate usually experiences from 25 to 200 mm per year of precipitation and in some years may experience no precipitation at all. Averages may be even less such as in Arica, Chile, there are usually two or three variations of a desert climate, a hot desert climate, a cold desert climate and, sometimes, a mild desert climate. To determine whether a location has a climate, the precipitation threshold is determined. If the areas precipitation is less than half the threshold. Hot desert climates are found under the subtropical ridge where there is largely unbroken sunshine for the whole year due to the stable descending air. These areas are located between 30 degrees south and 30 degrees north latitude, under the subtropical latitudes called the horse latitudes, hot desert climates are generally hot, sunny and dry year-round. Hot desert climates also reach similar latitudes in the Middle East, North Africa, hot desert climates usually feature hot, sometimes exceptionally hot, periods of the year. In many locations featuring a hot climate, maximum temperatures of over 40 °C are not uncommon in summer. The world absolute heat records, over 50 °C, are generally in the hot deserts, some desert locations consistently experience very high temperatures all year long, even during wintertime. These locations feature some of the highest annual average temperatures recorded on Earth and this last feature is seen in some parts of deserts of Africa and Arabia. During colder periods of the year, night-time temperatures can drop to freezing or below due to the radiation loss under the clear skies. However, very rarely do temperatures drop far below freezing, only one region in Europe has a hot desert climate, Province of Almeria, Province of Alicante and Province of Murcia in South Eastern Spain. Cold desert climates usually feature warm and dry summers, though summers typically are not quite as hot as summers in hot desert climates, unlike hot desert climates, cold desert climates tend to feature cold winters with rare snow. Cold desert climates are found at higher altitudes than hot desert climates. A cold desert climate is found in temperate zones, usually in the rain shadow of high mountains. A classic example of this is the Patagonian Desert in Argentina bounded by the Andes to its west, in the case of Central Asia, mountains restrict precipitation from the monsoon. The Gobi desert in Mongolia is an example of this. Though hot in summer, it shares the cold winters of the rest of Central Asia
4.
Biome
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A biome /ˈbaɪoʊm/ is a community of plants and animals that have common characteristics for the environment they exist in, and can be found over a range of continents. Spanning continents, biomes are distinct biological communities that have formed in response to a shared physical climate, biome is a broader term than habitat, any biome can comprise a variety of habitats. While a biome can cover large ares, a microbiome is a mix of organisms that coexist in a space as well. For example, the microbiome is the collection of bacteria, viruses. The biotas of the Earth make up the biosphere, the term was suggested in 1916 by Clements, originally as a synonym for biotic community of Möbius. In 1935, Tansley added the climatic and soil aspects to the idea, the International Biological Program projects popularized the concept of biome. However, in contexts, the term biome is used in a different manner. Both includes many biomes in fact and their boundaries must therefore be drawn arbitrarily and their characterization made according to the average conditions that predominate in them. A1978 study on North American grasslands found a positive correlation between evapotranspiration in mm/yr and above-ground net primary production in g/m2/yr. These findings help explain the categories used in Holdridge’s bioclassification scheme, Holdridge uses the four axes to define 30 so-called humidity provinces, which are clearly visible in his diagram. While this scheme largely ignores soil and sun exposure, Holdridge acknowledged that these were important and his scheme can be seen as a simplification of Holdridges, more readily accessible, but missing Holdridges greater specificity. Whittaker based his approach on theoretical assertions and empirical sampling and he was in a unique position to make such a holistic assertion because he had previously compiled a review of biome classifications. Physiognomy, the apparent characteristics, outward features, or appearance of communities or species. Biome, a grouping of terrestrial ecosystems on a continent that are similar in vegetation structure, physiognomy, features of the environment. Formation, a kind of community of plants on a given continent. Biome-type, grouping of convergent biomes or formations of different continents, whittakers distinction between biome and formation can be simplified, formation is used when applied to plant communities only, while biome is used when concerned with both plants and animals. Whittakers convention of biome-type or formation-type is simply a method to categorize similar communities. Whittaker considered four main ecoclines in the terrestrial realm, changes in physiognomic complexity vary with how favorable of an environment exists
5.
Steppe
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In South Africa they are referred to as Veld. The prairie is an example of a steppe, though it is not usually called such and it may be semi-desert, or covered with grass or shrubs or both, depending on the season and latitude. The term is used to denote the climate encountered in regions too dry to support a forest. The soil is typically of chernozem type, steppes are usually characterized by a semi-arid and continental climate. Extremes can be recorded in the summer of up to 45 °C and in winter, besides this huge difference between summer and winter, the differences between day and night are also very great. In the highlands of Mongolia,30 °C can be reached during the day with sub-zero °C readings at night, the mid-latitude steppes can be summarized by hot summers and cold winters, averaging 250–510 mm of precipitation per year. Precipitation level alone is not what defines a steppe climate, potential evapotranspiration must also be taken into account, the Eurasian Grass-Steppe of the temperate grasslands, savannas, and shrublands had a role in the spread of the horse, the wheel, and the Indo-European languages. The Indo-European expansion and diverse invasions of horse archer civilizations of the steppe eventually led to, the Pannonian Plain is another steppe region in eastern Europe, primarily Hungary. Another large steppe area is located in the central United States, western Canada, the shortgrass prairie steppe is the westernmost part of the Great Plains region. The Channeled Scablands in Southern British Columbia and Washington State is an example of a region in North America outside of the Great Plains. In South America, cold steppe can be found in Patagonia, relatively small steppe areas can be found in the interior of the South Island of New Zealand. In Asia, a subtropical steppe can be found in semi-arid lands that fringe the Thar Desert of the Indian subcontinent, in Australia, subtropical steppe can be found in a belt surrounding the most severe deserts of the continent and around the Musgrave Ranges. Ecology and Conservation of Steppe-land Birds by Manuel B. Morales, Santi Mañosa, Jordi Camprodón, international Symposium on Ecology and Conservation of steppe-land birds
6.
Poaceae
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Poaceae or Gramineae is a large and nearly ubiquitous family of monocotyledonous flowering plants known as grasses. Poaceae includes the cereal grasses, bamboos and the grasses of natural grassland and cultivated lawns, Grasses have stems that are hollow except at the nodes and narrow alternate leaves borne in two ranks. The lower part of each leaf encloses the stem, forming a leaf-sheath, with ca 780 genera and around 12,000 species, Poaceae are the fifth-largest plant family, following the Asteraceae, Orchidaceae, Fabaceae and Rubiaceae. Grasslands such as savannah and prairie grasses are dominant are estimated to constitute 40. 5% of the land area of the Earth, excluding Greenland. Grasses are also an important part of the vegetation in many habitats, including wetlands, forests. Though commonly called grasses, seagrasses, rushes, and sedges fall outside this family, the rushes and sedges are related to the Poaceae, being members of the order Poales, but the seagrasses are members of order Alismatales. The name Poaceae was given by John Hendley Barnhart in 1895, based on the tribe Poeae described in 1814 by Robert Brown, the term is derived from the Ancient Greek πόα. Grasses include some of the most versatile plant life-forms, a cladogram shows subfamilies and approximate species numbers in brackets, Before 2005, fossil findings indicated that grasses evolved around 55 million years ago. Recent findings of grass-like phytoliths in Cretaceous dinosaur coprolites have pushed this back to 66 million years ago. In 2011, revised dating of the origins of the rice tribe Oryzeae suggested a date as early as 107 to 129 Mya, a multituberculate mammal with grass-eating adaptations seems to suggest that grasses were already around at 120 mya. This separation occurred within the short time span of about 4 million years. Grass leaves are always alternate and distichous, and have parallel veins. Each leaf is differentiated into a lower sheath hugging the stem, the leaf blades of many grasses are hardened with silica phytoliths, which discourage grazing animals, some, such as sword grass, are sharp enough to cut human skin. A membranous appendage or fringe of hairs called the ligule lies at the junction between sheath and blade, preventing water or insects from penetrating into the sheath, flowers of Poaceae are characteristically arranged in spikelets, each having one or more florets. The spikelets are further grouped into panicles or spikes, the part of the spikelet that bears the florets is called the rachilla. A spikelet consists of two bracts at the base, called glumes, followed by one or more florets, a floret consists of the flower surrounded by two bracts, one external—the lemma—and one internal—the palea. The flowers are usually hermaphroditic—maize being an important exception—and anemophilous or wind-pollinated, the perianth is reduced to two scales, called lodicules, that expand and contract to spread the lemma and palea, these are generally interpreted to be modified sepals. This complex structure can be seen in the image on the right, the fruit of grasses is a caryopsis, in which the seed coat is fused to the fruit wall
7.
Shrub
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A shrub or bush is a small to medium-sized woody plant. It is distinguished from a tree by its multiple stems and shorter height, plants of many species may grow either into shrubs or trees, depending on their growing conditions. Small, low shrubs, generally less than 2 m tall, such as lavender, periwinkle, an area of cultivated shrubs in a park or a garden is known as a shrubbery. When clipped as topiary, suitable species or varieties of shrubs develop dense foliage, many shrubs respond well to renewal pruning, in which hard cutting back to a stool results in long new stems known as canes. Other shrubs respond better to selective pruning to reveal their structure, shrubs in common garden practice are generally considered broad-leaved plants, though some smaller conifers such as mountain pine and common juniper are also shrubby in structure. Species that grow into a shrubby habit may be deciduous or evergreen
8.
Contour line
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A contour line of a function of two variables is a curve along which the function has a constant value. It is a cross-section of the graph of the function f parallel to the x, y plane. In cartography, a contour line joins points of elevation above a given level. A contour map is a map illustrated with contour lines, for example a map, which thus shows valleys and hills. The contour interval of a map is the difference in elevation between successive contour lines. More generally, a line for a function of two variables is a curve connecting points where the function has the same particular value. The gradient of the function is always perpendicular to the contour lines, when the lines are close together the magnitude of the gradient is large, the variation is steep. A level set is a generalization of a line for functions of any number of variables. Contour lines are curved, straight or a mixture of lines on a map describing the intersection of a real or hypothetical surface with one or more horizontal planes. The configuration of these contours allows map readers to infer relative gradient of a parameter, in the latter case, the method of interpolation affects the reliability of individual isolines and their portrayal of slope, pits and peaks. Contour lines are given specific names beginning iso- according to the nature of the variable being mapped. Specific names are most common in meteorology, where multiple maps with different variables may be viewed simultaneously, the prefix iso- can be replaced with isallo- to specify a contour line connecting points where a variable changes at the same rate during a given time period. The words isoline and isarithm are general terms covering all types of contour line, an isogon is a contour line for a variable which measures direction. In meteorology and in geomagnetics, the term isogon has specific meanings which are described below, an isocline is a line joining points with equal slope. In population dynamics and in geomagnetics, the terms isocline and isoclinic line have specific meanings which are described below, equidistant is a line of equal distance from a given point, line, polyline. In geography, the word isopleth is used for lines that depict a variable which cannot be measured at a point. An example is population density, which can be calculated by dividing the population of a district by the surface area of that district. Each calculated value is presumed to be the value of the variable at the centre of the area, the idea of an isopleth map can be compared with that of a choropleth map
9.
Tropics
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The tropics are a region of the Earth surrounding the equator. The tropics are also referred to as the zone and the torrid zone. The tropics include all the areas on the Earth where the Sun is at a point directly overhead at least once during the solar year. The tropics are distinguished from the climatic and biomatic regions of Earth, which are the middle latitudes. Tropical is sometimes used in a sense for a tropical climate to mean warm to hot and moist year-round. Many tropical areas have a dry and wet season, the wet season, rainy season or green season, is the time of year, ranging from one or more months, when most of the average annual rainfall in a region falls. Areas with wet seasons are disseminated across portions of the tropics and subtropics, under the Köppen climate classification, for tropical climates, a wet season month is defined as a month where average precipitation is 60 millimetres or more. Tropical rainforests technically do not have dry or wet seasons, since their rainfall is distributed through the year. When the wet season occurs during the season, or summer, precipitation falls mainly during the late afternoon. The wet season is a time when air quality improves, freshwater quality improves and vegetation grows significantly, floods cause rivers to overflow their banks, and some animals to retreat to higher ground. Soil nutrients diminish and erosion increases, the incidence of malaria increases in areas where the rainy season coincides with high temperatures. Animals have adaptation and survival strategies for the wetter regime, unfortunately, the previous dry season leads to food shortages into the wet season, as the crops have yet to mature. Regions within the tropics may well not have a tropical climate, there are alpine tundra and snow-capped peaks, including Mauna Kea, Mount Kilimanjaro, and the Andes as far south as the northernmost parts of Chile and Argentina. Under the Köppen climate classification, much of the area within the tropics is classed not as tropical but as dry including the Sahara Desert. Tropical plants and animals are those native to the tropics. Tropical ecosystems may consist of rainforests, dry forests, spiny forests, desert. There are often significant areas of biodiversity, and species present, particularly in rainforests. In biogeography, the tropics are divided into Paleotropics and Neotropics, together, they are sometimes referred to as the Pantropic
