Nowadays, the number of forest fire is increasing frequently around the world. It is due to increase in global temperature of the earth . This is also an indicator of climate change. Due to increase in forest fire, the number of wildlives has been decreased and number of vegetation has been listed in the threatened species.
Sunday, March 20, 2011
Thursday, March 10, 2011
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot. Quantitatively, temperature is measured with thermometers, which may be calibrated to a variety of temperature scales.
Much of the world uses the Celsius scale (°C) for most temperature measurements. It has the same incremental scaling as the Kelvin scale used by scientists, but fixes its null point, at 0°C = 273.15K, the freezing point of water.[note 1] Few countries, most notably the United States, use the Fahrenheit scale for common purposes, a historical scale on which water freezes at 32 °F and boils at 212 °F.
For practical purposes of scientific temperature measurement, the International System of Units (SI) defines a scale and unit for the thermodynamic temperature by using the easily reproducible temperature of the triple point of water as a second reference point. For historical reasons, the triple point is fixed at 273.16 units of the measurement increment, which has been named the kelvin in honor of the Scottish physicist who first defined the scale. The unit symbol of the kelvin is K.
Temperature is one of the principal properties studied in the field of thermodynamics. Particularly important in this field are the differences in temperature between regions of matter, because such differences are the driving force for heat,[1] which is the transfer of thermal energy. Spontaneously, heat flows only from regions of higher temperature to regions of lower temperature. If no heat is transferred between two objects, the objects have the same temperature.
In the classical thermodynamic approach to temperature, temperature of an object varies with the speed of the particles it contains, raised to the second power. Therefore, temperature is tied directly to the mean kinetic energy of particles moving relative to the center of mass coordinates for that object. Temperature is an intensive variable because it is independent of the bulk amount of elementary entities contained inside, be they atoms, molecules, or electrons. In order for the temperature of a system to be defined, the system must be in thermodynamic equilibrium. Temperature may be considered to vary with position only if, for every point, there is a small neighborhood around that point can be treated as a thermodynamic system in equilibrium (i.e. local thermodynamic equilibrium). In the statistical thermodynamic approach, degrees of freedom are used instead of particles.
In a more fundamental approach, the empirical definition of temperature arises from the conditions of thermodynamic equilibrium, expressed as the zeroth law of thermodynamics.[2] When two systems are in thermal equilibrium, they have the same temperature,[3] which is also a matter of common experience. The extension of this principle as an equivalence relation between multiple systems fundamentally justifies the use of a thermometer and prescribes the principles of its construction to measure temperature.[4][5] While the zeroth law permits the definition of a set of many empirical scales of temperature, the second law of thermodynamics selects the definition of a single preferred, absolute temperature function,[6] whence called the thermodynamic temperature. This function is the variation of the internal energy with respect to changes in the entropy of a system. Its natural, intrinsic origin or null point is absolute zero at which the entropy of any system is at a minimum. Although this is the lowest absolute temperature described by the model, the third law of thermodynamics postulates that absolute zero cannot be attained by any physical system.
Much of the world uses the Celsius scale (°C) for most temperature measurements. It has the same incremental scaling as the Kelvin scale used by scientists, but fixes its null point, at 0°C = 273.15K, the freezing point of water.[note 1] Few countries, most notably the United States, use the Fahrenheit scale for common purposes, a historical scale on which water freezes at 32 °F and boils at 212 °F.
For practical purposes of scientific temperature measurement, the International System of Units (SI) defines a scale and unit for the thermodynamic temperature by using the easily reproducible temperature of the triple point of water as a second reference point. For historical reasons, the triple point is fixed at 273.16 units of the measurement increment, which has been named the kelvin in honor of the Scottish physicist who first defined the scale. The unit symbol of the kelvin is K.
Temperature is one of the principal properties studied in the field of thermodynamics. Particularly important in this field are the differences in temperature between regions of matter, because such differences are the driving force for heat,[1] which is the transfer of thermal energy. Spontaneously, heat flows only from regions of higher temperature to regions of lower temperature. If no heat is transferred between two objects, the objects have the same temperature.
In the classical thermodynamic approach to temperature, temperature of an object varies with the speed of the particles it contains, raised to the second power. Therefore, temperature is tied directly to the mean kinetic energy of particles moving relative to the center of mass coordinates for that object. Temperature is an intensive variable because it is independent of the bulk amount of elementary entities contained inside, be they atoms, molecules, or electrons. In order for the temperature of a system to be defined, the system must be in thermodynamic equilibrium. Temperature may be considered to vary with position only if, for every point, there is a small neighborhood around that point can be treated as a thermodynamic system in equilibrium (i.e. local thermodynamic equilibrium). In the statistical thermodynamic approach, degrees of freedom are used instead of particles.
In a more fundamental approach, the empirical definition of temperature arises from the conditions of thermodynamic equilibrium, expressed as the zeroth law of thermodynamics.[2] When two systems are in thermal equilibrium, they have the same temperature,[3] which is also a matter of common experience. The extension of this principle as an equivalence relation between multiple systems fundamentally justifies the use of a thermometer and prescribes the principles of its construction to measure temperature.[4][5] While the zeroth law permits the definition of a set of many empirical scales of temperature, the second law of thermodynamics selects the definition of a single preferred, absolute temperature function,[6] whence called the thermodynamic temperature. This function is the variation of the internal energy with respect to changes in the entropy of a system. Its natural, intrinsic origin or null point is absolute zero at which the entropy of any system is at a minimum. Although this is the lowest absolute temperature described by the model, the third law of thermodynamics postulates that absolute zero cannot be attained by any physical system.
Rainfall
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface. On Earth, it is the condensation of atmospheric water vapor into drops of water heavy enough to fall, often making it to the surface. Two processes, possibly acting together, can lead to air becoming saturated leading to rainfall: cooling the air or adding water vapor to the air. Virga is precipitation that begins falling to the earth but evaporates before reaching the surface; it is one of the ways air can become saturated. Precipitation forms via collision with other rain drops or ice crystals within a cloud. Rain drops range in size from oblate, pancake-like shapes for larger drops, to small spheres for smaller drops.
Moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts is the major method of rain production. If enough moisture and upward motion is present, precipitation falls from convective clouds (those with strong upward vertical motion) such as cumulonimbus (thunderstorms) which can organize into narrow rainbands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation which forces moist air to condense and fall out as rainfall along the sides of mountains. On the leeward side of mountains, desert climates can exist due to the dry air caused by downslope flow which causes heating and drying of the air mass. The movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes. Rain is the primary source of freshwater for most areas of the world, providing suitable conditions for diverse ecosystems, as well as water for hydroelectric power plants and crop irrigation. Rainfall is measured through the use of rain gauges. Rainfall amounts are estimated actively by weather radar and passively by weather satellites.
The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities. Global warming is also causing changes in the precipitation pattern globally, including wetter conditions across eastern North America and drier conditions in the tropics. Precipitation is a major component of the water cycle, and is responsible for depositing most of the fresh water on the planet. The globally-averaged annual precipitation is 990 millimetres (39 in). Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Antarctica is the Earth's driest continent. Rain is also known or suspected on other worlds, composed of methane, iron, neon, and sulfuric acid rather than water.
Moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts is the major method of rain production. If enough moisture and upward motion is present, precipitation falls from convective clouds (those with strong upward vertical motion) such as cumulonimbus (thunderstorms) which can organize into narrow rainbands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation which forces moist air to condense and fall out as rainfall along the sides of mountains. On the leeward side of mountains, desert climates can exist due to the dry air caused by downslope flow which causes heating and drying of the air mass. The movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes. Rain is the primary source of freshwater for most areas of the world, providing suitable conditions for diverse ecosystems, as well as water for hydroelectric power plants and crop irrigation. Rainfall is measured through the use of rain gauges. Rainfall amounts are estimated actively by weather radar and passively by weather satellites.
The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities. Global warming is also causing changes in the precipitation pattern globally, including wetter conditions across eastern North America and drier conditions in the tropics. Precipitation is a major component of the water cycle, and is responsible for depositing most of the fresh water on the planet. The globally-averaged annual precipitation is 990 millimetres (39 in). Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Antarctica is the Earth's driest continent. Rain is also known or suspected on other worlds, composed of methane, iron, neon, and sulfuric acid rather than water.
Shrubs
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m (15–20 ft) tall. A large number of plants can be either shrubs or trees, depending on the growing conditions they experience. Small, low shrubs such as lavender, periwinkle and thyme are often termed subshrubs.
An area of cultivated shrubs in a park or garden is known as a shrubbery. When clipped as topiary, shrubs generally have dense foliage and many small leafy branches growing close together. 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 and character.
Shrubs in common garden practice are generally broad-leaved plants, though some smaller conifers such as Mountain Pine and Common Juniper are also shrubby in structure. Shrubs can be either deciduous or evergreen.
An area of cultivated shrubs in a park or garden is known as a shrubbery. When clipped as topiary, shrubs generally have dense foliage and many small leafy branches growing close together. 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 and character.
Shrubs in common garden practice are generally broad-leaved plants, though some smaller conifers such as Mountain Pine and Common Juniper are also shrubby in structure. Shrubs can be either deciduous or evergreen.
vegetation
Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader than the term flora which refers exclusively to species composition. Perhaps the closest synonym is plant community, but vegetation can, and often does, refer to a wider range of spatial scales than that term does, including scales as large as the global. Primeval redwood forests, coastal mangrove stands, sphagnum bogs, desert soil crusts, roadside weed patches, wheat fields, cultivated gardens and lawns; all are encompassed by the term vegetation.
Diseases
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs.[1][2] It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune diseases. In humans, "disease" is often used more broadly to refer to any condition that causes pain, dysfunction, distress, social problems, and/or death to the person afflicted, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injuries, disabilities, disorders, syndromes, infections. Isolated symptoms, deviant behaviors, and atypical variations of structure and function, while in other contexts and for other purposes these may be considered distinguishable categories. Diseases usually affect people not only physically, but also emotionally, as contracting and living with many diseases can alter one's perspective on life, and their personality.
Death due to disease is called death by natural causes. There are four main types of disease: pathogenic disease, deficiency disease, hereditary disease, and physiological disease.
Diseases can also be classified as communicable and non-communicable disease.
Death due to disease is called death by natural causes. There are four main types of disease: pathogenic disease, deficiency disease, hereditary disease, and physiological disease.
Diseases can also be classified as communicable and non-communicable disease.
Floods
A flood is an overflow of an expanse of water that submerges land.[1] The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water.[2] In the sense of "flowing water", the word may also be applied to the inflow of the tide. Flooding may result from the volume of water within a body of water, such as a river or lake, which overflows or breaks levees, with the result that some of the water escapes its usual boundaries.[3]
While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, it is not a significant flood unless such escapes of water endanger land areas used by man like a village, city or other inhabited area.
Floods can also occur in rivers, when flow exceeds the capacity of the river channel, particularly at bends or meanders. Floods often cause damage to homes and businesses if they are placed in natural flood plains of rivers. While flood damage can be virtually eliminated by moving away from rivers and other bodies of water, since time out of mind, people have lived and worked by the water to seek sustenance and capitalize on the gains of cheap and easy travel and commerce by being near water. That humans continue to inhabit areas threatened by flood damage is evidence that the perceived value of living near the water exceeds the cost of repeated periodic flooding.
The word "flood" comes from the Old English flod, a word common to Germanic languages (compare German Flut, Dutch vloed from the same root as is seen in flow, float; also compare with Latin fluctus, flumen). Deluge myths are mythical stories of a great flood sent by a deity or deities to destroy civilization as an act of divine retribution, and are featured in the mythology of many cultures.
While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, it is not a significant flood unless such escapes of water endanger land areas used by man like a village, city or other inhabited area.
Floods can also occur in rivers, when flow exceeds the capacity of the river channel, particularly at bends or meanders. Floods often cause damage to homes and businesses if they are placed in natural flood plains of rivers. While flood damage can be virtually eliminated by moving away from rivers and other bodies of water, since time out of mind, people have lived and worked by the water to seek sustenance and capitalize on the gains of cheap and easy travel and commerce by being near water. That humans continue to inhabit areas threatened by flood damage is evidence that the perceived value of living near the water exceeds the cost of repeated periodic flooding.
The word "flood" comes from the Old English flod, a word common to Germanic languages (compare German Flut, Dutch vloed from the same root as is seen in flow, float; also compare with Latin fluctus, flumen). Deluge myths are mythical stories of a great flood sent by a deity or deities to destroy civilization as an act of divine retribution, and are featured in the mythology of many cultures.
Landslide
A landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments. Although the action of gravity is the primary driving force for a landslide to occur, there are other contributing factors affecting the original slope stability. Typically, pre-conditional factors build up specific sub-surface conditions that make the area/slope prone to failure, whereas the actual landslide often requires a trigger before being released.
Forests
A forest, also referred to as a wood or the woods and less often as a "wold" (or "weald"), "holt", or "frith" (or "firth"), is an area with a high density of trees. There are many definitions for forest, based on the various criteria.[1][vague] These plant communities cover approximately 9.4% of the Earth's surface (or 30% of total land area), though they once covered much more (about 50% of total land area), in many different regions and function as habitats for organisms, hydrologic flow modulators, and soil conservers, constituting one of the most important aspects of the Earth's biosphere. Although a forest is classified primarily by trees a forest ecosystem is defined intrinsically with additional species such as fungi.[2]
A typical forest is composed of the overstory (or upper tree layer of the canopy) and the understory. The understory is further subdivided into the shrub layer, herb layer, and sometimes also moss layer. In some complex forests, there is also a well-defined lower tree layer.
A typical forest is composed of the overstory (or upper tree layer of the canopy) and the understory. The understory is further subdivided into the shrub layer, herb layer, and sometimes also moss layer. In some complex forests, there is also a well-defined lower tree layer.
Glaciers
A glacier (pronounced UK: /ˈɡlæsiər/ GLASS-ee-ər or US: /ˈɡleɪʃər/ GLAY-shər) is a large persistent body of ice. Originating on land, a glacier flows slowly due to stresses induced by its weight. The crevasses and other distinguishing features of a glacier are due to its flow. Another consequence of glacier flow is the transport of rock and debris abraded from its substrate and resultant landforms like cirques and moraines. A glacier forms in a location where the accumulation of snow and sleet exceeds the amount of snow that melts. Over many years, often decades or centuries, a glacier will eventually form as the snow compacts and turns to ice. A glacier is distinct from sea ice and lake ice that form on the surface of bodies of water.
The word glacier comes from French. It is derived from the Vulgar Latin *glacia and ultimately from Latin glacies meaning ice.[1] The processes and features caused by glaciers and related to them are referred to as glacial. The process of glacier establishment, growth and flow is called glaciation. The corresponding area of study is called glaciology. Glaciers are important components of the global cryosphere.
On Earth, 99% of glacial ice is contained within vast ice sheets in the polar regions, but glaciers may be found in mountain ranges of every continent except Australia. In the tropics, glaciers occur only on high mountains.[2]
Glacial ice is the largest reservoir of freshwater on Earth. Many glaciers store water during one season and release it later as meltwater, a water source that is especially important for plants, animals and human uses when other sources may be scant.
Because glacial mass is affected by long-term climate changes, e.g., precipitation, mean temperature, and cloud cover, glacial mass changes are considered among the most sensitive indicators of climate change and are a major source of variations in sea level.
The word glacier comes from French. It is derived from the Vulgar Latin *glacia and ultimately from Latin glacies meaning ice.[1] The processes and features caused by glaciers and related to them are referred to as glacial. The process of glacier establishment, growth and flow is called glaciation. The corresponding area of study is called glaciology. Glaciers are important components of the global cryosphere.
On Earth, 99% of glacial ice is contained within vast ice sheets in the polar regions, but glaciers may be found in mountain ranges of every continent except Australia. In the tropics, glaciers occur only on high mountains.[2]
Glacial ice is the largest reservoir of freshwater on Earth. Many glaciers store water during one season and release it later as meltwater, a water source that is especially important for plants, animals and human uses when other sources may be scant.
Because glacial mass is affected by long-term climate changes, e.g., precipitation, mean temperature, and cloud cover, glacial mass changes are considered among the most sensitive indicators of climate change and are a major source of variations in sea level.
Mountains
A mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill. The adjective montane is used to describe mountainous areas and things associated with them. The study of mountains is called Orography.
Exogeology deals with planetary mountains, which in that branch of science are usually called montes (singular—mons). The highest mountain on Earth based from sea level is Mount Everest (8,848 m (29,029 ft)) in the Himalayas of Asia. The highest known mountain in the Solar System is Olympus Mons on the planet Mars at 21,171 m (69,459 ft)
Exogeology deals with planetary mountains, which in that branch of science are usually called montes (singular—mons). The highest mountain on Earth based from sea level is Mount Everest (8,848 m (29,029 ft)) in the Himalayas of Asia. The highest known mountain in the Solar System is Olympus Mons on the planet Mars at 21,171 m (69,459 ft)
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