1.
Climate of the Alps
–
The climate of the Alps is the climate, or average weather conditions over a long period of time, of the exact middle Alpine region of Europe. As air rises from sea level to the regions of the atmosphere the temperature decreases. The position of the Alps in the central European continent profoundly affects the climate of all the surrounding regions, six regions or zones, which are best distinguished by their characteristic vegetation, are found in the Alps. It is an error to suppose that these are indicated by absolute height above sea level, local conditions of exposure to the Sun, protection from cold winds, or the reverse, are of primary importance in determining the climate and the corresponding vegetation. The Subalpine is the region which mainly determines the manner of life of the population of the Alps, roughly one quarter of the land lying between the summits of the Alps is available for cultivation. Of this low country, about one half may be vineyards and grain fields, while the remainder produces forage, of the high country, about half is utterly barren, consisting of snow fields, glaciers, bare rock, lakes and stream beds. The other half is divided between forest and pasture, and the product of this half largely supports the large population. The larger villages are mostly in the region, but in many parts of the Alps the villages stand in the subalpine region at elevations varying from 1200 m to 1700–1800 m. The most characteristic feature of this region is the prevalence of coniferous trees that and these play a most important part in the natural economy of the country. They retain the soil by their roots, protect the valleys from destructive avalanches, in the conifer forests of the Alps the prevailing species are the Norway spruce and the silver fir, on siliceous soil the European larch flourishes. The Scots pine is found at a lower level and rarely forms forests. The Swiss pine is found scattered at intervals throughout the Alps but is not common, the mountain pine is common at higher altitudes, often forming a distinct zone of Krummholz above the level of its congeners on the higher mountains. The Alps are eponymous of the Alpine climate typical of the Alps between the line up to the permanent snow line, roughly between 1800 m and 2500 m. This alpine region contains the full beauty and variety of vegetation of the Alps. The region contains many shrubs, Three species of rhododendron have masses of red or pink flowers, Three species of bilberry are associated with the junipers. Several dwarf willows grow near the snow line, on the higher parts of lofty mountains in the Alps more snow falls in each year than melts. Mountain snow does not lie in beds of uniform thickness and some parts are more exposed to the sun, beds of snow commonly alternate with exposed slopes covered with brilliant vegetation without an obvious boundary of perpetual snow. But this is only as far as the conditions are similar
Climate of the Alps
–
Flora typical of the Alpine region of the Alps
2.
White Mountain Peak
–
It is the fourteenth most topographically prominent peak in the contiguous United States. The effects of altitude on physiology are studied at the Barcroft Station, there is a winding dirt road leading to the summit station that is usually cleared of snow between late June and November. Access is restricted to only by a locked gate about 2 miles before Barcroft station. Open gate days are typically 2 Sundays in the summer, the normal round trip hike from the gate is about 14 miles round trip with less than 2,600 feet of vertical gain. However, there are two different dips in the trail of about 250 feet each, adding up to an elevation gain during the roundtrip of over 3500 feet. The open gate shaves about 4 miles and 790 feet of gain off the round trip and this route is popular with mountain bikers. The peak is approached from the north where it is guarded by a narrow arête or knife-edge ridge. A better nontechnical alternative to the road would be to drive as far as possible up Leidy Canyon from Fish Lake Valley. From the flats it is an easy traverse south into the cirque of the North Fork, a moderate scramble up the ridge between the North Branch and the larger cirque of the main North Fork leads to the easier upper slopes of the peak. While the peak does not require climbing skills, it still poses a serious challenge to hikers because of the high altitude. The summit and the station at 12,470 feet has an alpine tundra climate. Most of the mountain, however, has a warm summer continental climate or semi-arid climate, winters are extremely severe, with the peak receiving upwards of 13 feet of snow annually. List of mountain peaks of California List of highest points in California by county List of Ultras of the United States White Mountain Peak, special Collections & Archives, UC San Diego Library
White Mountain Peak
–
White Mountain Peak from trail, June 2004
White Mountain Peak
–
White Mountain Research Center Summit Lab.
White Mountain Peak
–
Panorama from top of White Mountain looking to the east, south and west.
3.
California
–
California is the most populous state in the United States and the third most extensive by area. Located on the western coast of the U. S, California is bordered by the other U. S. states of Oregon, Nevada, and Arizona and shares an international border with the Mexican state of Baja California. Los Angeles is Californias most populous city, and the second largest after New York City. The Los Angeles Area and the San Francisco Bay Area are the nations second- and fifth-most populous urban regions, California also has the nations most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The Central Valley, an agricultural area, dominates the states center. What is now California was first settled by various Native American tribes before being explored by a number of European expeditions during the 16th and 17th centuries, the Spanish Empire then claimed it as part of Alta California in their New Spain colony. The area became a part of Mexico in 1821 following its war for independence. The western portion of Alta California then was organized as the State of California, the California Gold Rush starting in 1848 led to dramatic social and demographic changes, with large-scale emigration from the east and abroad with an accompanying economic boom. If it were a country, California would be the 6th largest economy in the world, fifty-eight percent of the states economy is centered on finance, government, real estate services, technology, and professional, scientific and technical business services. Although it accounts for only 1.5 percent of the states economy, the story of Calafia is recorded in a 1510 work The Adventures of Esplandián, written as a sequel to Amadis de Gaula by Spanish adventure writer Garci Rodríguez de Montalvo. The kingdom of Queen Calafia, according to Montalvo, was said to be a land inhabited by griffins and other strange beasts. This conventional wisdom that California was an island, with maps drawn to reflect this belief, shortened forms of the states name include CA, Cal. Calif. and US-CA. Settled by successive waves of arrivals during the last 10,000 years, various estimates of the native population range from 100,000 to 300,000. The Indigenous peoples of California included more than 70 distinct groups of Native Americans, ranging from large, settled populations living on the coast to groups in the interior. California groups also were diverse in their organization with bands, tribes, villages. Trade, intermarriage and military alliances fostered many social and economic relationships among the diverse groups, the first European effort to explore the coast as far north as the Russian River was a Spanish sailing expedition, led by Portuguese captain Juan Rodríguez Cabrillo, in 1542. Some 37 years later English explorer Francis Drake also explored and claimed a portion of the California coast in 1579. Spanish traders made unintended visits with the Manila galleons on their trips from the Philippines beginning in 1565
California
–
A forest of redwood trees in
Redwood National Park
California
–
Flag
California
–
Mount Shasta
California
–
Aerial view of the
California Central Valley
4.
Weather
–
Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the lowest level of the atmosphere, Weather refers to day-to-day temperature and precipitation activity, whereas climate is the term for the averaging of atmospheric conditions over longer periods of time. When used without qualification, weather is understood to mean the weather of Earth. Weather is driven by air pressure, temperature and moisture differences between one place and another and these differences can occur due to the suns angle at any particular spot, which varies with latitude. The strong temperature contrast between polar and tropical air gives rise to the largest scale atmospheric circulations, the Hadley Cell, the Ferrel Cell, the Polar Cell, Weather systems in the mid-latitudes, such as extratropical cyclones, are caused by instabilities of the jet stream flow. Because the Earths axis is tilted relative to its orbital plane, on Earths surface, temperatures usually range ±40 °C annually. Over thousands of years, changes in Earths orbit can affect the amount and distribution of energy received by the Earth, thus influencing long-term climate. Surface temperature differences in turn cause pressure differences, higher altitudes are cooler than lower altitudes as most atmospheric heating is due to contact with the Earths surface while radiative losses to space are mostly constant. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. The Earths weather system is a system, as a result. Human attempts to control the weather have occurred throughout history, and there is evidence that human activities such as agriculture, studying how the weather works on other planets has been helpful in understanding how weather works on Earth. A famous landmark in the Solar System, Jupiters Great Red Spot, is a storm known to have existed for at least 300 years. However, weather is not limited to planetary bodies, a stars corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. The movement of mass ejected from the Sun is known as the solar wind, on Earth, the common weather phenomena include wind, cloud, rain, snow, fog and dust storms. Less common events include natural disasters such as tornadoes, hurricanes, typhoons, almost all familiar weather phenomena occur in the troposphere. Weather does occur in the stratosphere and can affect weather lower down in the troposphere, Weather occurs primarily due to air pressure, temperature and moisture differences between one place to another. These differences can occur due to the sun angle at any particular spot, in other words, the farther from the tropics one lies, the lower the sun angle is, which causes those locations to be cooler due the spread of the sunlight over a greater surface. The strong temperature contrast between polar and tropical air gives rise to the large scale atmospheric circulation cells and the jet stream, Weather systems in the mid-latitudes, such as extratropical cyclones, are caused by instabilities of the jet stream flow
Weather
–
Thunderstorm near Garajau,
Madeira
Weather
–
Cumulus mediocris cloud surrounded by
stratocumulus
Weather
–
New Orleans, Louisiana, after being struck by Hurricane Katrina. Katrina was a
Category 3 hurricane when it struck although it had been a category 5 hurricane in the
Gulf of Mexico.
Weather
–
Early morning sunshine over
Bratislava, Slovakia
5.
Climate
–
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
Climate
–
Atmospheric sciences
Climate
–
The world’s cloudy and sunny spots. NASA Earth Observatory map using data collected between July 2002 and April 2015.
6.
Tree line
–
The tree line is the edge of the habitat at which trees are capable of growing. It is found at high elevations and in frigid environments, beyond the tree line, trees cannot tolerate the environmental conditions. The tree line should not be confused with a lower timberline or forest line, at the tree line, tree growth is often sparse and stunted, with the last trees forming densely matted bushes, known as krummholz. The tree line, like other natural lines, appears well-defined from a distance. Trees grow shorter towards the inhospitable climate until they stop growing. The climate above the line of mountains is called an alpine climate. In the northern hemisphere treelines on north-facing slopes are lower than on south-facing slopes because the increased shade on north-facing slopes means the snowpack takes longer to melt and this shortens the growing season for trees. In the southern hemisphere, the slopes have the shorter growing season. The alpine tree line boundary is seldom abrupt, it forms a transition zone between closed forest below and treeless alpine tundra above. Environmentally dwarfed shrubs commonly forms the upper limit, the decrease in air temperature due to increasing elevation causes the alpine climate. Skin effects and topography can create microclimates that alter the general cooling trend, however, the number of degree days calculated from leaf temperatures may be very similar in the two kinds of timberlines. A series of warm summers in the 1940s seems to have permitted the establishment of “significant numbers” of spruce seedlings above the treeline in the hills near Fairbanks. Survival depends on a sufficiency of new growth to support the tree, the windiness of high-elevation sites is also a potent determinant of the distribution of tree growth. However, snow accumulation in sheltered gullies in the Selkirk Mountains of southeastern British Columbia causes timberline to be 400 metres lower than on exposed intervening shoulders. In a desert, the line marks the driest places where trees can grow. These tend to be called the tree line and occur below about 5,000 ft elevation in the Desert Southwestern United States. In some mountainous areas, higher elevations above the line or on equator-facing and leeward slopes can result in low rainfall. This dries out the soil, resulting in an arid environment unsuitable for trees
Tree line
–
Tree line above
St. Moritz, Switzerland. May 2009
Tree line
–
In this view of an alpine tree line, the distant line looks particularly sharp. The foreground shows the transition from trees to no trees. These trees are stunted in growth and one-sided because of cold and constant wind.
Tree line
–
An alpine tree line in the
Tararua Range
Tree line
–
Severe winter climate conditions at alpine tree line causes stunted
krummholz growth.
Karkonosze,
Poland.
7.
Holdridge life zone
–
The Holdridge life zones system is a global bioclimatic scheme for the classification of land areas. It was first published by Leslie Holdridge in 1947, and updated in 1967 and it is a relatively simple system based on few empirical data, giving objective mapping criteria. A basic assumption of the system is that soil and climax vegetation can be mapped once climate is known. While it was first designed for tropical and subtropical areas, the system applies globally, the system has found a major use in assessing the possible changes in natural vegetation patterns due to global warming. The three axes of the subdivisions are, precipitation biotemperature potential evapotranspiration ratio to mean total annual precipitation. Further indicators incorporated into the system are, humidity provinces latitudinal regions altitudinal belts Biotemperature is based on the season length. It is measured as the mean of all temperatures above freezing, with all temperatures below freezing and above 30 °C adjusted to 0 °C, holdridges system uses biotemperature first, rather than the temperate latitude bias of Merriams life zones, and does not primarily consider elevation. The system is considered appropriate to the complexities of tropical vegetation than Merriams system. Potential evapotranspiration is the amount of water that would be evaporated and transpired if there were sufficient water available, high temperatures result in higher PET. Evapotranspiration is the sum of evaporation and plant transpiration from the Earths land surface to atmosphere, evapotranspiration can never be greater than PET. The ratio, Precipitation/PET, is the aridity index, with an AI<0.2 indicating arid/hyperarid, Coldest /\ / \ PET - -- - Rain Coldest regions have not much evapotranspiration nor precipitation, hence polar deserts
Holdridge life zone
–
Holdridge life zone classification scheme. Although conceived as three-dimensional by its originator, it is usually shown as a two-dimensional array of hexagons in a triangular frame.
8.
Biotemperature
–
The Holdridge life zones system is a global bioclimatic scheme for the classification of land areas. It was first published by Leslie Holdridge in 1947, and updated in 1967 and it is a relatively simple system based on few empirical data, giving objective mapping criteria. A basic assumption of the system is that soil and climax vegetation can be mapped once climate is known. While it was first designed for tropical and subtropical areas, the system applies globally, the system has found a major use in assessing the possible changes in natural vegetation patterns due to global warming. The three axes of the subdivisions are, precipitation biotemperature potential evapotranspiration ratio to mean total annual precipitation. Further indicators incorporated into the system are, humidity provinces latitudinal regions altitudinal belts Biotemperature is based on the season length. It is measured as the mean of all temperatures above freezing, with all temperatures below freezing and above 30 °C adjusted to 0 °C, holdridges system uses biotemperature first, rather than the temperate latitude bias of Merriams life zones, and does not primarily consider elevation. The system is considered appropriate to the complexities of tropical vegetation than Merriams system. Potential evapotranspiration is the amount of water that would be evaporated and transpired if there were sufficient water available, high temperatures result in higher PET. Evapotranspiration is the sum of evaporation and plant transpiration from the Earths land surface to atmosphere, evapotranspiration can never be greater than PET. The ratio, Precipitation/PET, is the aridity index, with an AI<0.2 indicating arid/hyperarid, Coldest /\ / \ PET - -- - Rain Coldest regions have not much evapotranspiration nor precipitation, hence polar deserts
Biotemperature
–
Holdridge life zone classification scheme. Although conceived as three-dimensional by its originator, it is usually shown as a two-dimensional array of hexagons in a triangular frame.
9.
Polar climate
–
The polar climate regions are characterized by a lack of warm summers. Every month in a polar climate has a temperature of less than 10 °C. Regions with polar climate cover more than 20% of the Earth, the sun shines for long hours in the summer, and for many fewer hours in the winter. A polar climate results in treeless tundra, glaciers, or a permanent or semi-permanent layer of ice and it has cool summers and very cold winters. There are two types of climate, ET, or tundra climate, and EF, or ice cap climate. A tundra climate is characterized by having at least one month whose average temperature is above 0 °C, in a tundra climate, trees cannot grow, but other specialized plants can grow. In an ice cap climate, no plants can grow, many high altitude locations on Earth have a climate where no month has an average temperature of 10 °C or higher, but as this is due to elevation, this climate is referred to as Alpine climate. Alpine climate can mimic either tundra or ice cap climate, on Earth, the only continent where the ice cap polar climate is predominant is Antarctica. All but a few isolated areas on the island of Greenland also have the ice cap climate. Coastal regions of Greenland that do not have permanent ice sheets have the less extreme tundra climates, large areas in northern Canada and northern Alaska have tundra climate, changing to ice cap climate in the most northern parts of Canada. These subantarctic lowlands are found closer to the equator than the coastal tundras of the Arctic basin, some parts of the Arctic are covered by ice year-round, and nearly all parts of the Arctic experience long periods with some form of ice on the surface. Average January temperatures range from about −40 to 0 °C, average July temperatures range from about −10 to 10 °C, with some land areas occasionally exceeding 30 °C in summer. The Arctic consists of ocean that is surrounded by land. As such, the climate of much of the Arctic is moderated by the ocean water, in summer, the presence of the nearby water keeps coastal areas from warming as much as they might otherwise, just as it does in temperate regions with maritime climates. The climate of Antarctica is the coldest on the whole of Earth, Antarctica has the lowest temperature ever recorded, −89.2 °C at Vostok Station. It is also dry, averaging 166 millimetres of precipitation per year. Even so, on most parts of the continent the snow melts and is eventually compressed to become the glacial ice that makes up the ice sheet. Weather fronts rarely penetrate far into the continent, there have been several attempts at quantifying what constitutes a polar climate
Polar climate
–
A
polar bear with cub
Polar climate
–
Solar radiation has a lower intensity in polar regions because it travels a longer distance through the atmosphere, and is spread across a larger surface area.
10.
Temperature
–
A temperature is an objective comparative measurement of hot or cold. It is measured by a thermometer, several scales and units exist for measuring temperature, the most common being Celsius, Fahrenheit, and, especially in science, Kelvin. Absolute zero is denoted as 0 K on the Kelvin scale, −273.15 °C on the Celsius scale, the kinetic theory offers a valuable but limited account of the behavior of the materials of macroscopic bodies, especially of fluids. Temperature is important in all fields of science including physics, geology, chemistry, atmospheric sciences, medicine. The Celsius scale is used for temperature measurements in most of the world. Because of the 100 degree interval, it is called a centigrade scale.15, the United States commonly uses the Fahrenheit scale, on which water freezes at 32°F and boils at 212°F at sea-level atmospheric pressure. Many scientific measurements use the Kelvin temperature scale, named in honor of the Scottish physicist who first defined it and it is a thermodynamic or absolute temperature scale. Its zero point, 0K, is defined to coincide with the coldest physically-possible temperature and its degrees are defined through thermodynamics. The temperature of zero occurs at 0K = −273. 15°C. For historical reasons, the triple point temperature of water is fixed at 273.16 units of the measurement increment, Temperature is one of the principal quantities in the study of thermodynamics. There is a variety of kinds of temperature scale and it may be convenient to classify them as empirically and theoretically based. Empirical temperature scales are historically older, while theoretically based scales arose in the middle of the nineteenth century, empirically based temperature scales rely directly on measurements of simple physical properties of materials. For example, the length of a column of mercury, confined in a capillary tube, is dependent largely on temperature. Such scales are only within convenient ranges of temperature. For example, above the point of mercury, a mercury-in-glass thermometer is impracticable. A material is of no use as a thermometer near one of its phase-change temperatures, in spite of these restrictions, most generally used practical thermometers are of the empirically based kind. Especially, it was used for calorimetry, which contributed greatly to the discovery of thermodynamics, nevertheless, empirical thermometry has serious drawbacks when judged as a basis for theoretical physics. Theoretically based temperature scales are based directly on theoretical arguments, especially those of thermodynamics, kinetic theory and they rely on theoretical properties of idealized devices and materials
Temperature
–
Annual mean temperature around the world
Temperature
–
Body temperature variation
Temperature
–
A typical Celsius thermometer measures a winter day temperature of -17 °C.
Temperature
–
Plots of pressure vs temperature for three different gas samples extrapolated to absolute zero.
11.
Radiation
–
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. Radiation is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles, Ionizing radiation carries more than 10 eV, which is enough to ionize atoms and molecules, and break chemical bonds. This is an important distinction due to the difference in harmfulness to living organisms. A common source of ionizing radiation is radioactive materials that emit α, β, or γ radiation, consisting of helium nuclei, electrons or positrons, gamma rays, X-rays and the higher energy range of ultraviolet light constitute the ionizing part of the electromagnetic spectrum. The lower-energy, longer-wavelength part of the spectrum including visible light, infrared light, microwaves and this type of radiation only damages cells if the intensity is high enough to cause excessive heating. Ultraviolet radiation has some features of both ionizing and non-ionizing radiation and these properties derive from ultraviolets power to alter chemical bonds, even without having quite enough energy to ionize atoms. The word radiation arises from the phenomenon of waves radiating from a source and this aspect leads to a system of measurements and physical units that are applicable to all types of radiation. This law does not apply close to a source of radiation or for focused beams. Radiation with sufficiently high energy can ionize atoms, that is to say it can knock electrons off atoms, ionization occurs when an electron is stripped from an electron shell of the atom, which leaves the atom with a net positive charge. Because living cells and, more importantly, the DNA in those cells can be damaged by this ionization, thus ionizing radiation is somewhat artificially separated from particle radiation and electromagnetic radiation, simply due to its great potential for biological damage. While an individual cell is made of trillions of atoms, only a fraction of those will be ionized at low to moderate radiation powers. If the source of the radiation is a radioactive material or a nuclear process such as fission or fusion. Particle radiation is subatomic particles accelerated to relativistic speeds by nuclear reactions, because of their momenta they are quite capable of knocking out electrons and ionizing materials, but since most have an electrical charge, they dont have the penetrating power of ionizing radiation. The exception is neutron particles, see below, there are several different kinds of these particles, but the majority are alpha particles, beta particles, neutrons, and protons. Roughly speaking, photons and particles with energies above about 10 electron volts are ionizing, particle radiation from radioactive material or cosmic rays almost invariably carries enough energy to be ionizing. The radiation is invisible and not directly detectable by human senses, as a result, in some cases, it may lead to secondary emission of visible light upon its interaction with matter, as in the case of Cherenkov radiation and radio-luminescence. Ionizing radiation has many uses in medicine, research and construction. Ultraviolet, of wavelengths from 10 nm to 125 nm, ionizes air molecules, causing it to be absorbed by air
Radiation
–
Illustration of the relative abilities of three different types of
ionizing radiation to penetrate solid matter. Typical alpha particles (α) are stopped by a sheet of paper, while beta particles (β) are stopped by an aluminium plate. Gamma radiation (γ) is damped when it penetrates lead. Note caveats in the text about this simplified diagram.
12.
Convection
–
Convection is the movement of groups of molecules within fluids such as liquids or gases, and within rheids. Convection takes place through advection, diffusion or both, convection cannot take place in solids because neither bulk current flows nor significant diffusion can take place in solids. Diffusion of heat can take place in solids, but that is called heat conduction, convective heat transfer is one of the major types of heat transfer, and convection is also a major mode of mass transfer in fluids. In the context of heat and mass transfer, the convection is used to refer to the sum of advective and diffusive transfer. In common use the term convection may refer loosely to heat transfer by convection, as opposed to mass transfer by convection, sometimes convection is even used to refer specifically to free heat convection as opposed to forced heat convection. However, in mechanics the correct use of the word is the general sense, convection can be qualified in terms of being natural, forced, gravitational, granular, or thermomagnetic. It may also be said to be due to combustion, capillary action, or Marangoni, heat transfer by natural convection plays a role in the structure of Earths atmosphere, its oceans, and its mantle. Discrete convective cells in the atmosphere can be seen as clouds, natural convection also plays a role in stellar physics. The word convection may have different but related usages in different scientific or engineering contexts or applications. The broader sense is in fluid mechanics, where convection refers to the motion of fluid regardless of cause, however, in thermodynamics convection often refers specifically to heat transfer by convection. Additionally, convection includes fluid movement both by bulk motion and by the motion of individual particles, however, in some cases, convection is taken to mean only advective phenomena. Convection occurs on a scale in atmospheres, oceans, planetary mantles. Fluid movement during convection may be slow, or it may be obvious and rapid. On astronomical scales, convection of gas and dust is thought to occur in the disks of black holes. Convective heat transfer is a mechanism of heat transfer occurring because of bulk motion of fluids, heat is the entity of interest being advected, and diffused. Heat is transferred by convection in numerous examples of naturally occurring fluid flow, such as, wind, oceanic currents, convection is also used in engineering practices of homes, industrial processes, cooling of equipment, etc. The rate of heat transfer may be improved by the use of a heat sink. For instance, a typical computer CPU will have a fan to ensure its operating temperature is kept within tolerable limits
Convection
–
A heat sink provides a large surface area for convection to efficiently carry away heat.
Convection
–
Idealised depiction of the global circulation on Earth
Convection
–
Stages of a thunderstorm's life.
Convection
–
An illustration of the structure of the
Sun and a
red giant star, showing their convective zones. These are the granular zones in the outer layers of these stars.
13.
Visible spectrum
–
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nm, in terms of frequency, this corresponds to a band in the vicinity of 430–770 THz. The spectrum does not, however, contain all the colors that the human eyes, unsaturated colors such as pink, or purple variations such as magenta, are absent, for example, because they can be made only by a mix of multiple wavelengths. Colors containing only one wavelength are called pure colors or spectral colors. Visible wavelengths pass through the window, the region of the electromagnetic spectrum that allows wavelengths to pass largely unattenuated through the Earths atmosphere. An example of this phenomenon is that clean air scatters blue light more than red wavelengths, the optical window is also referred to as the visible window because it overlaps the human visible response spectrum. The near infrared window lies just out of the vision, as well as the Medium Wavelength IR window. In the 13th century, Roger Bacon theorized that rainbows were produced by a process to the passage of light through glass or crystal. In the 17th century, Isaac Newton discovered that prisms could disassemble and reassemble white light and he was the first to use the word spectrum in this sense in print in 1671 in describing his experiments in optics. The result is red light is bent less sharply than violet as it passes through the prism. Newton divided the spectrum into seven named colors, red, orange, yellow, green, blue, indigo, the human eye is relatively insensitive to indigos frequencies, and some people who have otherwise-good vision cannot distinguish indigo from blue and violet. For this reason, some commentators, including Isaac Asimov, have suggested that indigo should not be regarded as a color in its own right. However, the evidence indicates that what Newton meant by indigo, comparing Newtons observation of prismatic colors to a color image of the visible light spectrum shows that indigo corresponds to what is today called blue, whereas blue corresponds to cyan. In the 18th century, Goethe wrote about optical spectra in his Theory of Colours, Goethe used the word spectrum to designate a ghostly optical afterimage, as did Schopenhauer in On Vision and Colors. Goethe argued that the spectrum was a compound phenomenon. Where Newton narrowed the beam of light to isolate the phenomenon, Goethe observed that a wider aperture produces not a spectrum but rather reddish-yellow, the spectrum appears only when these edges are close enough to overlap. Young was the first to measure the wavelengths of different colors of light, the connection between the visible spectrum and color vision was explored by Thomas Young and Hermann von Helmholtz in the early 19th century
Visible spectrum
–
White
light is
dispersed by a
prism into the colors of the visible spectrum.
Visible spectrum
–
Newton's observation of prismatic colors (
David Brewster 1855)
14.
Greenhouse effect
–
The greenhouse effect is the process by which radiation from a planets atmosphere warms the planets surface to a temperature above what it would be without its atmosphere. If a planets atmosphere contains radiatively active gases the atmosphere radiate energy in all directions. Part of this radiation is directed towards the surface, warming it, greenhouse gases in the atmosphere radiate energy, some of which is directed to the surface and lower atmosphere. The mechanism that produces this difference between the surface temperature and the effective temperature is due to the atmosphere and is known as the greenhouse effect. Earth’s natural greenhouse effect is critical to supporting life, human activities, primarily the burning of fossil fuels and clearing of forests, have intensified the natural greenhouse effect, causing global warming. The mechanism is named after a faulty analogy with the effect of radiation passing through glass. The way a greenhouse retains heat is fundamentally different, as a works by reducing airflow. The existence of the effect was argued for by Joseph Fourier in 1824. The effect was more fully quantified by Svante Arrhenius in 1896, however, the term greenhouse was not used to refer to this effect by any of these scientists, the term was first used in this way by Nils Gustaf Ekholm in 1901. Earth receives energy from the Sun in the form of ultraviolet, visible, of the total amount of solar energy available at the top of the atmosphere, about 26% is reflected to space by the atmosphere and clouds and 19% is absorbed by the atmosphere and clouds. Most of the energy is absorbed at the surface of Earth. Because the Earths surface is colder than the photosphere of the Sun, most of this thermal radiation is absorbed by the atmosphere, thereby warming it. In addition to the absorption of solar and thermal radiation, the atmosphere gains heat by sensible, the atmosphere radiates energy both upwards and downwards, the part radiated downwards is absorbed by the surface of Earth. This leads to an equilibrium temperature than if the atmosphere were absent. An ideal thermally conductive blackbody at the distance from the Sun as Earth would have a temperature of about 5.3 °C. However, because Earth reflects about 30% of the incoming sunlight, the surface temperature of this hypothetical planet is 33 °C below Earths actual surface temperature of approximately 14 °C. The basic mechanism can be qualified in a number of ways, the atmosphere near the surface is largely opaque to thermal radiation, and most heat loss from the surface is by sensible heat and latent heat transport. Radiative energy losses become increasingly important higher in the atmosphere, largely because of the concentration of water vapor
Greenhouse effect
–
A modern
Greenhouse in
RHS Wisley
Greenhouse effect
–
A representation of the exchanges of energy between the source (the
Sun), the Earth's surface, the
Earth's atmosphere, and the ultimate sink
outer space. The ability of the atmosphere to capture and recycle energy emitted by the Earth surface is the defining characteristic of the greenhouse effect.
15.
Adiabatic process
–
In thermodynamics, an adiabatic process is one that occurs without transfer of heat or matter between a thermodynamic system and its surroundings. In an adiabatic process, energy is transferred only as work, the adiabatic process provides a rigorous conceptual basis for the theory used to expound the first law of thermodynamics, and as such it is a key concept in thermodynamics. The adiabatic flame temperature is the temperature that would be achieved by a if the process of combustion took place in the absence of heat loss to the surroundings. A process that does not involve the transfer of heat or matter into or out of a system, so that Q =0, is called an adiabatic process, the assumption that a process is adiabatic is a frequently made simplifying assumption. Even though the cylinders are not insulated and are quite conductive, the same can be said to be true for the expansion process of such a system. The assumption of adiabatic isolation of a system is a useful one, the behaviour of actual machines deviates from these idealizations, but the assumption of such perfect behaviour provide a useful first approximation of how the real world works. According to Laplace, when sound travels in a gas, there is no loss of heat in the medium and the propagation of sound is adiabatic. For this adiabatic process, the modulus of elasticity E = γP where γ is the ratio of specific heats at constant pressure and at constant volume, such a process is called an isentropic process and is said to be reversible. Fictively, if the process is reversed, the energy added as work can be recovered entirely as work done by the system, if the walls of a system are not adiabatic, and energy is transferred in as heat, entropy is transferred into the system with the heat. Such a process is neither adiabatic nor isentropic, having Q >0, naturally occurring adiabatic processes are irreversible. The transfer of energy as work into an isolated system can be imagined as being of two idealized extreme kinds. In one such kind, there is no entropy produced within the system, in nature, this ideal kind occurs only approximately, because it demands an infinitely slow process and no sources of dissipation. The other extreme kind of work is work, for which energy is added as work solely through friction or viscous dissipation within the system. The second law of thermodynamics observes that a process, of transfer of energy as work, always consists at least of isochoric work. Every natural process, adiabatic or not, is irreversible, with ΔS >0, the adiabatic compression of a gas causes a rise in temperature of the gas. Adiabatic expansion against pressure, or a spring, causes a drop in temperature, in contrast, free expansion is an isothermal process for an ideal gas. Adiabatic heating occurs when the pressure of a gas is increased from work done on it by its surroundings and this finds practical application in diesel engines which rely on the lack of quick heat dissipation during their compression stroke to elevate the fuel vapor temperature sufficiently to ignite it. Adiabatic heating occurs in the Earths atmosphere when an air mass descends, for example, in a wind, Foehn wind
Adiabatic process
–
For a simple substance, during an adiabatic process in which the volume increases, the
internal energy of the working substance must decrease
16.
Heat of vaporization
–
The enthalpy of vaporization is a function of the pressure at which that transformation takes place. The heat of vaporization is temperature-dependent, though a constant heat of vaporization can be assumed for small temperature ranges, the heat of vaporization diminishes with increasing temperature and it vanishes completely at a certain point called the critical temperature. Above the critical temperature, the liquid and vapor phases are indistinguishable, values are usually quoted in J/mol or kJ/mol, although kJ/kg or J/g, and older units like kcal/mol, cal/g and Btu/lb are sometimes still used, among others. The increase in the energy can be viewed as the energy required to overcome the intermolecular interactions in the liquid. Hence helium has a particularly low enthalpy of vaporization,0.0845 kJ/mol, as the van der Waals forces between helium atoms are particularly weak. This is particularly true of metals, which often form covalently bonded molecules in the gas phase, in these cases, the enthalpy of atomization must be used to obtain a true value of the bond energy. An alternative description is to view the enthalpy of condensation as the heat which must be released to the surroundings to compensate for the drop in entropy when a gas condenses to a liquid. These two definitions are equivalent, the point is the temperature at which the increased entropy of the gas phase overcomes the intermolecular forces. Estimation of the enthalpy of vaporization of electrolyte solutions can be carried out using equations based on the chemical thermodynamic models. The vaporization of metals is a key step in metal vapor synthesis, gmelin-Handbuch der anorganischen Chemie /08 a. NIST Chemistry WebBook Young, Francis W. Sears, Mark W. Zemansky, Hugh D
Heat of vaporization
–
Fig. 1 Schematic cross section of the proposed vaporization model for monatomic liquids with one atomic surface layer.
Heat of vaporization
–
Temperature-dependency of the heats of vaporization for water, methanol, benzene, and acetone.
17.
Dew point
–
Dew point is the temperature to which air must be cooled to become saturated with water vapor. When further cooled, the water vapor will condense to form liquid dew. Dew point is called frost point when the temperature is below freezing. The measurement of dew point is related to humidity, a higher dew point means there will be more moisture in the air. Given that all the factors influencing humidity remain constant, at ground level the relative humidity rises as the temperature falls. This is because water vapor condenses as the temperature falls. Dew point temperature is never greater than the air temperature because relative humidity cannot exceed 100%. In technical terms, the dew point is the temperature at which the vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates. At temperatures below the dew point, the rate of condensation will be greater than that of evaporation, the condensed water is called dew when it forms on a solid surface. The condensed water is called either fog or a cloud, depending on its altitude, a high relative humidity implies that the dew point is closer to the current air temperature. Relative humidity of 100% indicates the dew point is equal to the current temperature, when the moisture content remains constant and temperature increases, relative humidity decreases. General aviation pilots use dew point data to calculate the likelihood of carburetor icing and fog, at a given temperature but independent of barometric pressure, the dew point is a consequence of the absolute humidity, the mass of water per unit volume of air. If both the temperature and pressure rise, however, the dew point will increase and the humidity will decrease accordingly. Reducing the absolute humidity without changing other variables will bring the dew point back down to its initial value, in the same way, increasing the absolute humidity after a temperature drop brings the dew point back down to its initial level. If the temperature rises in conditions of constant pressure, then the dew point will remain constant but the relative humidity will drop. For this reason, a constant relative humidity with different temperatures implies that when it is hotter, a higher fraction of the air is present as water vapor compared to when it is cooler. At a given barometric pressure but independent of temperature, the dew point indicates the fraction of water vapor in the air, or, put differently. If the pressure rises without changing this mole fraction, the dew point will rise accordingly, reducing the mole fraction, i. e. making the air less humid, would bring the dew point back down to its initial value
Dew point
–
Humidity and hygrometry
Dew point
–
This graph shows the maximum percentage, by mass, of water vapor that air at sea-level pressure across a range of temperatures can contain. For a lower ambient pressure, a curve has to be drawn above the current curve. A higher ambient pressure yields a curve under the current curve.
18.
Cloud
–
The experiment began operation in November 2009. The primary goal is to understand the influence of cosmic rays on aerosols and clouds. Although its design is optimised to address the cosmic ray question, CLOUD allows as well to measure aerosol nucleation, atmospheric aerosols and their effect on clouds are recognised by the IPCC as main source of uncertainty in present radiative forcing and climate models. The core of the experiment is a steel chamber of 26m³ volume filled with synthetic air made from liquid nitrogen. The chamber atmosphere and pressure is being measured and regulated by various instrumentations, the aerosol chamber can be exposed to an adjustable particle beam simulating GCRs at various altitude or latitude. The chamber contains a field cage to control the drift of small ions. The ionisation produced by cosmic rays can be removed with an electric field. Besides, humidity and temperature inside the chamber can be regulated, CERN posted a 2009 progress report on the CLOUD project. J. Kirkby reviews developments in the CERN CLOUD project and planned tests and he describes cloud nucleation mechanisms which appear energetically favourable and depend on GCRs. On 24 August 2011, preliminary research published in the journal Nature showed there was a connection between Cosmic Rays and aerosol nucleation, the first CLOUD experiments showed that sulphuric acid as such has a much smaller effect than had been assumed. In 2014, CLOUD researchers presented newer experimental results showing an interaction between oxidised biogenic vapours and sulphuric acid and this new process may account for seasonal variations in atmospheric aerosol particles, which are being related to higher global tree emissions in the northern hemisphere summer. Besides biogenic vapours produced by plants, another class of trace vapours and these are found close to their primary sources, e. g. animal husbandry, while alpha-pinene is generally found over landmasses. The experiments show that sulfuric acid and oxidized organic vapors at low concentrations reproduce suitable particle nucleation rates, CLOUD insofar allows to explain a large fraction of cloud seeds in the lower atmosphere involving sulphuric acid and biogenic aerosols. This result does not support the hypothesis that cosmic rays significantly affect climate, dunne et al. have presented the main outcomes of 10 years of results obtained at the CLOUD experiment performed at CERN. They have studied in detail the physico-chemical mechanisms and the kinetics of aerosols formation
Cloud
19.
Latitude
–
In geography, latitude is a geographic coordinate that specifies the north–south position of a point on the Earths surface. Latitude is an angle which ranges from 0° at the Equator to 90° at the poles, lines of constant latitude, or parallels, run east–west as circles parallel to the equator. Latitude is used together with longitude to specify the location of features on the surface of the Earth. Without qualification the term latitude should be taken to be the latitude as defined in the following sections. Also defined are six auxiliary latitudes which are used in special applications, there is a separate article on the History of latitude measurements. Two levels of abstraction are employed in the definition of latitude and longitude, in the first step the physical surface is modelled by the geoid, a surface which approximates the mean sea level over the oceans and its continuation under the land masses. The second step is to approximate the geoid by a mathematically simpler reference surface, the simplest choice for the reference surface is a sphere, but the geoid is more accurately modelled by an ellipsoid. The definitions of latitude and longitude on such surfaces are detailed in the following sections. Lines of constant latitude and longitude together constitute a graticule on the reference surface, latitude and longitude together with some specification of height constitute a geographic coordinate system as defined in the specification of the ISO19111 standard. This is of importance in accurate applications, such as a Global Positioning System, but in common usage, where high accuracy is not required. In English texts the latitude angle, defined below, is denoted by the Greek lower-case letter phi. It is measured in degrees, minutes and seconds or decimal degrees, the precise measurement of latitude requires an understanding of the gravitational field of the Earth, either to set up theodolites or to determine GPS satellite orbits. The study of the figure of the Earth together with its field is the science of geodesy. These topics are not discussed in this article and this article relates to coordinate systems for the Earth, it may be extended to cover the Moon, planets and other celestial objects by a simple change of nomenclature. The primary reference points are the poles where the axis of rotation of the Earth intersects the reference surface, the plane through the centre of the Earth and perpendicular to the rotation axis intersects the surface at a great circle called the Equator. Planes parallel to the plane intersect the surface in circles of constant latitude. The Equator has a latitude of 0°, the North Pole has a latitude of 90° North, the latitude of an arbitrary point is the angle between the equatorial plane and the radius to that point. The latitude, as defined in this way for the sphere, is termed the spherical latitude
Latitude
–
A graticule on the Earth as a
sphere or an
ellipsoid. The lines from pole to pole are lines of constant
longitude, or meridians. The circles parallel to the
equator are lines of constant latitude, or parallels. The graticule determines the latitude and longitude of points on the surface. In this example meridians are spaced at 6° intervals and parallels at 4° intervals.
20.
Ocean
–
An ocean is a body of saline water that composes much of a planets hydrosphere. On Earth, an ocean is one of the major divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern, the word sea is often used interchangeably with ocean in American English but, strictly speaking, a sea is a body of saline water partly or fully enclosed by land. The ocean contains 97% of Earths water, and oceanographers have stated that less than 5% of the World Ocean has been explored, the total volume is approximately 1.35 billion cubic kilometers with an average depth of nearly 3,700 meters. As the world ocean is the component of Earths hydrosphere, it is integral to all known life, forms part of the carbon cycle. The world ocean is the habitat of 230,000 known species, but because much of it is unexplored, the origin of Earths oceans remains unknown, oceans are thought to have formed in the Hadean period and may have been the impetus for the emergence of life. Extraterrestrial oceans may be composed of water or other elements and compounds, the only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their histories, Mars and Venus are theorized to have had large water oceans. The Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, compounds such as salts and ammonia dissolved in water lower its freezing point so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of many planets and natural satellites, notably. The Solar Systems giant planets are thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may also exist on exoplanets and exomoons, including surface oceans of water within a circumstellar habitable zone. Ocean planets are a type of planet with a surface completely covered with liquid. The concept of Ōkeanós has an Indo-European connection, Greek Ōkeanós has been compared to the Vedic epithet ā-śáyāna-, predicated of the dragon Vṛtra-, who captured the cows/rivers. Related to this notion, the Okeanos is represented with a dragon-tail on some early Greek vases, though generally described as several separate oceans, these waters comprise one global, interconnected body of salt water sometimes referred to as the World Ocean or global ocean. This concept of a body of water with relatively free interchange among its parts is of fundamental importance to oceanography. The major oceanic divisions – listed below in descending order of area and volume – are defined in part by the continents, various archipelagos, Oceans are fringed by smaller, adjoining bodies of water such as seas, gulfs, bays, bights, and straits. The Mid-Oceanic Ridge of the World are connected and form the Ocean Ridge, the continuous mountain range is 65,000 km long, and the total length of the oceanic ridge system is 80,000 km long
Ocean
–
Surface of the
Atlantic Ocean meeting
Earth 's
planetary boundary layer and
troposphere.
Ocean
–
Artist's conception of subsurface ocean of Enceladus confirmed April 3, 2014.
Ocean
–
Two models for the composition of Europa predict a large subsurface ocean of liquid water. Similar models have been proposed for other celestial bodies in the Solar System
Ocean
–
Diagram showing a possible internal structure of
Ceres
21.
Precipitation (meteorology)
–
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation include drizzle, rain, sleet, snow, graupel, Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, so that the water condenses and precipitates. Thus, fog and mist are not precipitation but suspensions, because the vapor does not condense sufficiently to precipitate. Two processes, possibly acting together, can lead to air becoming saturated, Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called showers, moisture that is lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into clouds and rain. This process is active when freezing rain is occurring. A stationary front is often present near the area of freezing rain, provided necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely stratus and cumulonimbus. Eventually, the droplets will grow large enough to form raindrops. Lake-effect snowfall can be locally heavy, thundersnow is possible within a cyclones comma head and within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation, on the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. The movement of the trough, or intertropical convergence zone. Precipitation is a component of the water cycle, and is responsible for depositing the fresh water on the planet. Approximately 505,000 cubic kilometres of water falls as precipitation each year,398,000 cubic kilometres of it over the oceans and 107,000 cubic kilometres over land. Given the Earths surface area, that means the globally averaged annual precipitation is 990 millimetres, Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Precipitation may occur on celestial bodies, e. g. when it gets cold, Mars has precipitation which most likely takes the form of frost. Precipitation is a component of the water cycle, and is responsible for depositing most of the fresh water on the planet. Approximately 505,000 km3 of water falls as precipitation each year,398,000 km3 of it over the oceans, given the Earths surface area, that means the globally averaged annual precipitation is 990 millimetres. Mechanisms of producing precipitation include convective, stratiform, and orographic rainfall, Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with the surface, or ice
Precipitation (meteorology)
–
A thunderstorm with heavy precipitation
Precipitation (meteorology)
–
Long-term mean precipitation by month
Precipitation (meteorology)
–
Late-summer
rainstorm in
Denmark
Precipitation (meteorology)
–
Lenticular cloud forming due to mountains over Wyoming
22.
Snow
–
Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets, snowflakes take on a variety of shapes, basic among these are platelets, needles, columns and rime. As snow accumulates into a snowpack, it may blow into drifts, over time, accumulated snow metamorphoses, by sintering, sublimation and freeze-thaw. Where the climate is cold enough for year-to-year accumulation, a glacier may form, otherwise, snow typically melts seasonally, causing runoff into streams and rivers and recharging groundwater. Major snow-prone areas include the regions, the upper half of the Northern Hemisphere and mountainous regions worldwide with sufficient moisture. In the Southern Hemisphere, snow is confined primarily to mountainous areas, Snow affects ecosystems, as well, by providing an insulating layer during winter under which plants and animals are able to survive the cold. Snow develops in clouds that themselves are part of a weather system. The physics of snow crystal development in clouds results from a set of variables that include moisture content. The resulting shapes of the falling and fallen crystals can be classified into a number of shapes and combinations. Occasionally, some plate-like, dendritic and stellar-shaped snowflakes can form under clear sky with a cold temperature inversion present. Two additional and locally productive sources of snow are lake-effect storms and elevation effects, miid-latitude cyclones are low pressure areas which are capable of producing anything from cloudiness and mild snow storms to heavy blizzards. During a hemispheres fall, winter, and spring, the atmosphere over continents can be cold enough through the depth of the troposphere to cause snowfall, in the Northern Hemisphere, the northern side of the low pressure area produces the most snow. For the southern mid-latitudes, the side of a cyclone that produces the most snow is the southern side, a cold front, the leading edge of a cooler mass of air, can produce frontal snowsqualls—an intense frontal convective line, when temperature is near freezing at the surface. The strong convection that develops has enough moisture to produce whiteout conditions at places which line passes over as the wind causes intense blowing snow. This type of snowsquall generally lasts less than 30 minutes at any point along its path, in cases where there is a large amount of vertical growth and mixing the squall may develop embedded cumulonimbus clouds resulting in lightning and thunder which is dubbed thundersnow. A warm front can produce snow for a period, as warm, moist air overrides below-freezing air, often, snow transitions to rain in the warm sector behind the front. The same effect occurs over bodies of salt water, when it is termed ocean-effect or bay-effect snow. The effect is enhanced when the air mass is uplifted by the orographic influence of higher elevations on the downwind shores
Snow
–
Snow on the
Carpathian Mountains, Romania
Snow
–
Snow on the mountains of
Southern California
Snow
–
Satellite photo of sea-effect snow bands near the
Korean Peninsula
Snow
–
Road and trees covered in snow,
Bârnova
23.
Tropopause
–
The tropopause is the boundary in the Earths atmosphere between the troposphere and the stratosphere. Going upward from the surface, it is the point where air ceases to cool with height, more formally, the tropopause is the region of the atmosphere where the environmental lapse rate changes from positive, as it behaves in the troposphere, to the stratospheric negative one. The troposphere is one of the lowest layers of the Earths atmosphere, it is located right above the boundary layer. The troposphere extends upwards from right above the layer, and ranges in height from an average of 9 km at the poles. In the absence of inversions and not considering moisture, the lapse rate for this layer is 6.5 °C per kilometer, on average. The tropopause location coincides with the lowest point at which the lapse rate falls below a prescribed threshold. Since the tropopause responds to the temperature of the entire layer that lies underneath it, it is at its peak levels over the Equator. On account of this, the coolest layer in the lies at about 17 km over the equator. Due to the variation in starting height, the extremes are referred to as the equatorial tropopause. It is formed with the aid of potential vorticity, which is defined as the product of the isentropic density, instead of using the vertical temperature gradient as the defining variable, the dynamic tropopause surface is expressed in potential vorticity units. Nevertheless, the tropopause is useless at equatorial latitudes because the isentropes are almost vertical. For the extratropical tropopause in the Northern Hemisphere the WMO established a value of 1.5 PVU and it is also possible to define the tropopause in terms of chemical composition. For example, the stratosphere has much higher ozone concentrations than the upper troposphere. The tropopause is not a hard boundary, vigorous thunderstorms, for example, particularly those of tropical origin, will overshoot into the lower stratosphere and undergo a brief low-frequency vertical oscillation. Such oscillation sets up an atmospheric gravity wave capable of affecting both atmospheric and oceanic currents in the region. Most commercial aircraft are flown in the stratosphere, just above the tropopause. Jet stream Maximum parcel level Andrews, D. G. Holton, J. R. Leovy, C. B. R. Dmowska, Holton, a First Course in Atmospheric Thermodynamics
Tropopause
–
The tropopause lies higher in the tropics than at the poles.
Tropopause
–
Schematic showing the different layers of the atmosphere (not to scale). The tropopause is located between the troposphere and the stratosphere.
24.
Summit
–
A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. Mathematically, a summit is a maximum in elevation. The topographic terms acme, apex, peak, and zenith are synonymous, the UIAA definition is that a summit is independent if it has a prominence of 30 metres or more, it is a mountain if it has a prominence of at least 300 metres. This can be summarised as follows, A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top, Summit may also refer to the highest point along a line, trail, or route. In many parts of the western United States, the term refers to the highest point along a road, highway. For example, the highest point along Interstate 80 in California is referred to as Donner Summit while the highest point on Interstate 5 is Siskiyou Mountain Summit, geoid Hill List of highest mountains Maxima and minima Nadir Summit accordance Peak finder
Summit
–
The highest elevation summit, Mount Everest, shown with a climber at the summit wearing an oxygen mask. The summit is 8850 m (29,035 ft) elevation. (While the cruising altitude of jetliners is roughly 10,000 m (32,808 feet), they are pressurized.)
Summit
–
View from the summit of Switzerland's highest,
Monte Rosa
Summit
–
The summit of
Mount Damavand,
Iran, in winter
Summit
–
Jeff Davis Peak, one of the highest peaks entirely within
Nevada
25.
Sierra Nevada (U.S.)
–
The Sierra Nevada is a mountain range in the Western United States, between the Central Valley of California and the Basin and Range Province. The vast majority of the lies in the state of California. The Sierra runs 400 miles north-to-south, and is approximately 70 miles across east-to-west, the Sierra is home to three national parks, twenty wilderness areas, and two national monuments. These areas include Yosemite, Sequoia, and Kings Canyon National Parks, the character of the range is shaped by its geology and ecology. More than one hundred years ago during the Nevadan orogeny. The range started to uplift four M. A. ago, the uplift caused a wide range of elevations and climates in the Sierra Nevada, which are reflected by the presence of five life zones. Uplift continues due to faulting caused by forces, creating spectacular fault block escarpments along the eastern edge of the southern Sierra. The Sierra Nevada has a significant history, the California Gold Rush occurred in the western foothills from 1848 through 1855. Due to inaccessibility, the range was not fully explored until 1912, the Sierra Nevada lies in Central and Eastern California, with a very small but historically important spur extending into Nevada. West-to-east, the Sierra Nevadas elevation increases gradually from 1,000 feet in the Central Valley to an height of about 10,500 feet at its crest only 50–75 miles to the east. The east slope forms the steep Sierra Escarpment, unlike its surroundings, the range receives a substantial amount of snowfall and precipitation due to orographic lift. The Sierra Nevada stretches from the Susan River and Fredonyer Pass in the north to Tehachapi Pass in the south and it is bounded on the west by Californias Central Valley and on the east by the Basin and Range Province. The geographical boundary between the Sierra and the Cascades is virtually indistinguishable, with the Fredonyer Pass designation being traditional, physiographically, the Sierra is a section of the Cascade-Sierra Mountains province, which in turn is part of the larger Pacific Mountain System physiographic division. The range is drained on its western slope by the Central Valley watershed, the northern third of the western Sierra is part of the Sacramento River watershed, and the middle third is drained by the San Joaquin River. The eastern slope watershed of the Sierra is much narrower, its rivers flow out into the endorheic Great Basin of eastern California and western Nevada. Although none of the eastern rivers reach the sea, many of the streams from Mono Lake southwards are diverted into the Los Angeles Aqueduct which provides water to Southern California, the height of the mountains in the Sierra Nevada increases gradually from north to south. Between Fredonyer Pass and Lake Tahoe, the range from 5,000 feet to more than 9,000 feet. The crest near Lake Tahoe is roughly 9,000 feet high, farther south, the highest peak in Yosemite National Park is Mount Lyell
Sierra Nevada (U.S.)
–
The Sierra's
Mills Creek cirque (center) is on the west side of the
Sierra Crest, south of
Mono Lake (top, blue).
Sierra Nevada (U.S.)
–
Mount Whitney, the highest peak in the range and the contiguous United States
Sierra Nevada (U.S.)
–
The Sierra hosts many waterways, such as the
Tuolumne River.
Sierra Nevada (U.S.)
–
Mount Tallac above
Lake Tahoe
26.
Cascade Mountains
–
The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades, the small part of the range in British Columbia is referred to as the Canadian Cascades or, locally, as the Cascade Mountains. The highest peak in the range is Mount Rainier in Washington at 14,411 feet, the Cascades are part of the Pacific Oceans Ring of Fire, the ring of volcanoes and associated mountains around the Pacific Ocean. All of the eruptions in the contiguous United States over the last 200 years have been from Cascade volcanoes, the two most recent were Lassen Peak from 1914 to 1921 and a major eruption of Mount St. Helens in 1980. Minor eruptions of Mount St. Helens have also occurred since, the Cascade Range is a part of the American Cordillera, a nearly continuous chain of mountain ranges that form the western backbone of North America, Central America, and South America. The Cascades extend northward from Lassen Peak in northern California to the confluence of the Nicola, the Fraser River separates the Cascades from the Coast Mountains. The highest volcanoes of the Cascades, known as the High Cascades, dominate their surroundings and they often have a visual height of one mile or more. The highest peaks, such as the 14, 411-foot Mount Rainier, Mount Baker in Washington recorded a world-record single-season snowfall in the winter of 1998–99 with 1,140 inches. Prior to that year, Mount Rainier held the record for snow accumulation at Paradise in 1978. It is not uncommon for some places in the Cascades to have over 500 inches of snow accumulation, such as at Lake Helen. Most of the High Cascades are therefore white with snow and ice year-round, annual rainfall is as low as 9 inches on the eastern foothills due to a rain shadow effect. Beyond the eastern foothills is a plateau that was largely created 17 to 14 million years ago by the many flows of the Columbia River Basalt Group. Together, these sequences of fluid volcanic rock form the 200, 000-square-mile Columbia Plateau in eastern Washington, Oregon, the Columbia River Gorge is the only major break of the range in the United States. When the Cascades began to rise 7 million years ago in the Pliocene, as the range grew, erosion from the Columbia River was able to keep pace, creating the gorge and major pass seen today. The gorge also exposes uplifted and warped layers of basalt from the plateau, in early 1792, British navigator George Vancouver explored Puget Sound and gave English names to the high mountains he saw. Mount Baker was named for Vancouvers third lieutenant, Joseph Baker, although the first European to see it was Manuel Quimper, Mount Rainier was named after Admiral Peter Rainier. Later in 1792, Vancouver had his lieutenant William Robert Broughton explore the lower Columbia River and he named Mount Hood after Lord Samuel Hood, an admiral of the Royal Navy. Mount St. Helens was sighted by Vancouver in May 1792 and it was named for Alleyne FitzHerbert, 1st Baron St Helens, a British diplomat
Cascade Mountains
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Cascades in Washington, with
Mount Rainier, the highest mountain in the range, standing at 14,411 ft (4,392 m). Seen in the background (left to right) are
Mount Adams, the peak of
Mount Hood, and
Mount St. Helens.
Cascade Mountains
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Map of the Cascade Range showing major volcanic peaks
Cascade Mountains
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The
Columbia Gorge marks where the
Columbia River splits the Cascade Range between the states of Washington and Oregon.
Cascade Mountains
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West side view of
Mount Shuksan in summer as seen from
Artist Point in
Washington
27.
Rocky Mountains
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The Rocky Mountains, commonly known as the Rockies, are a major mountain range in western North America. The Rocky Mountains stretch more than 3,000 miles from the northernmost part of British Columbia, in western Canada, to New Mexico, in the Southwestern United States. Within the North American Cordillera, the Rockies are somewhat distinct from the Pacific Coast Ranges, the Rocky Mountains were initially formed from 80 million to 55 million years ago during the Laramide orogeny, in which a number of plates began to slide underneath the North American plate. The angle of subduction was shallow, resulting in a belt of mountains running down western North America. Since then, further tectonic activity and erosion by glaciers have sculpted the Rockies into dramatic peaks, at the end of the last ice age, humans started to inhabit the mountain range. The first mention of their present name by a European was in the journal of Jacques Legardeur de Saint-Pierre in 1752, the Rocky Mountains are commonly defined as stretching from the Liard River in British Columbia south to the Rio Grande in New Mexico. The United States definition of the Rockies includes the Cabinet and Salish Mountains of Idaho and their counterparts north of the Kootenai River, the Columbia Mountains, are considered a separate system in Canada, lying to the west of the huge Rocky Mountain Trench. This runs the length of British Columbia from its beginnings in the middle Flathead River valley in western Montana to the bank of the Liard River. The Rockies vary in width from 70 to 300 miles, also west of the Rocky Mountain Trench, farther north and facing the Muskwa Range across the trench, are the Stikine Ranges and Omineca Mountains of the Interior Mountains system of British Columbia. A small area east of Prince George, British Columbia on the side of the Trench. In Canada geographers define three main groups of ranges, the Continental Ranges, Hart Ranges and Muskwa Ranges, the Muskwa and Hart Ranges together comprise what is known as the Northern Rockies. The western edge of the Rockies includes ranges such as the Wasatch near Salt Lake City, the Great Basin and Columbia River Plateau separate these sub-ranges from distinct ranges further to the west, most prominent among which are the Sierra Nevada, Cascade Range and Coast Mountains. The Rocky Mountain System within the United States is a United States physiographic region, the Rocky Mountains are notable for containing the highest peaks in central North America. The ranges highest peak is Mount Elbert located in Colorado at 14,440 feet above sea level, Mount Robson in British Columbia, at 12,972 feet, is the highest peak in the Canadian Rockies. The Continental Divide of the Americas is located in the Rocky Mountains, triple Divide Peak in Glacier National Park is so named because water that falls on the mountain reaches not only the Atlantic and Pacific, but Hudson Bay as well. Farther north in Alberta, the Athabasca and other rivers feed the basin of the Mackenzie River, see Rivers of the Rocky Mountains for a list of rivers. Human population is not very dense in the Rocky Mountains, with an average of four people per square kilometer, however, the human population grew rapidly in the Rocky Mountain states between 1950 and 1990. The 40-year statewide increases in range from 35% in Montana to about 150% in Utah
Rocky Mountains
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Moraine Lake, and the
Valley of the Ten Peaks,
Banff National Park,
Alberta,
Canada
Rocky Mountains
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The Front Range of the Rocky Mountains near
Denver, Colorado
Rocky Mountains
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The
Tetons are a rugged subrange in Wyoming
Rocky Mountains
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Mount Robson in
British Columbia.
28.
Appalachian Mountains
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The Appalachian Mountains, often called the Appalachians, are a system of mountains in eastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period and it once reached elevations similar to those of the Alps and the Rocky Mountains before naturally occurring erosion. The Appalachian chain is a barrier to east-west travel, as it forms a series of alternating ridgelines, definitions vary on the precise boundaries of the Appalachians. A common variant definition does not include the Adirondack Mountains, which belong to the Grenville Orogeny and have a different geological history from the rest of the Appalachians. The range covers parts of the islands of Saint Pierre and Miquelon, the system is divided into a series of ranges, with the individual mountains averaging around 3,000 ft. The highest of the group is Mount Mitchell in North Carolina at 6,684 feet, the term Appalachian refers to several different regions associated with the mountain range. Most broadly, it refers to the mountain range with its surrounding hills. The Ouachita Mountains in Arkansas and Oklahoma were originally part of the Appalachians as well, the name was soon altered by the Spanish to Apalachee and used as a name for the tribe and region spreading well inland to the north. Pánfilo de Narváezs expedition first entered Apalachee territory on June 15,1528, now spelled Appalachian, it is the fourth-oldest surviving European place-name in the US. After the de Soto expedition in 1540, Spanish cartographers began to apply the name of the tribe to the mountains themselves. The first cartographic appearance of Apalchen is on Diego Gutierrezs map of 1562, the name was not commonly used for the whole mountain range until the late 19th century. A competing and often more popular name was the Allegheny Mountains, Alleghenies, in the early 19th century, Washington Irving proposed renaming the United States either Appalachia or Alleghania. In U. S. dialects in the regions of the Appalachians. In northern parts of the range, it is pronounced /ˌæpəˈleɪtʃᵻnz/ or /ˌæpəˈleɪʃᵻnz/, the third syllable is like lay. There is often debate between the residents of the regions as to which pronunciation is the more correct one. Elsewhere, a commonly accepted pronunciation for the adjective Appalachian is /ˌæpəˈlætʃiən/, the whole system may be divided into three great sections, Northern, The northern section runs from the Canadian province of Newfoundland and Labrador to the Hudson River. The Monteregian Hills, which cross the Green Mountains in Quebec, are also unassociated with the Appalachians, Central, The central section goes from the Hudson Valley to the New River running through Virginia and West Virginia. Southern, The southern section runs from the New River onwards and it consists of the prolongation of the Blue Ridge, which is divided into the Western Blue Ridge Front and the Eastern Blue Ridge Front, the Ridge-and-Valley Appalachians, and the Cumberland Plateau
Appalachian Mountains
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View from the slopes of
Back Allegheny Mountain, looking east; visible are
Allegheny Mountain (in the
Monongahela National Forest of
West Virginia, middle distance) and
Shenandoah Mountain (in the
George Washington National Forest of
Virginia, far distance)
Appalachian Mountains
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Detail of Diego Gutiérrez's 1562 map of the Western Hemisphere, showing the first known use of a variation of the place name "Appalachia" ("Apalchen") - from the map Americae sive qvartae orbis partis nova et exactissima descriptio
Appalachian Mountains
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Shaded relief map of the
Cumberland Plateau and
Ridge-and-Valley Appalachians on the
Virginia –
West Virginia border
Appalachian Mountains
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Old
fault exposed by roadcut near
Harrisburg,
Pennsylvania, along
Interstate 81, such faults are common in the folded Appalachians
29.
Mauna Loa
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Mauna Loa is one of five volcanoes that form the Island of Hawaii in the U. S. state of Hawaiʻi in the Pacific Ocean. The largest subaerial volcano in both mass and volume, Mauna Loa has historically considered the largest volcano on Earth. Lava eruptions from Mauna Loa are silica-poor and very fluid, Mauna Loa has probably been erupting for at least 700,000 years, and may have emerged above sea level about 400,000 years ago. The oldest-known dated rocks are not older than 200,000 years, the volcanos magma comes from the Hawaii hotspot, which has been responsible for the creation of the Hawaiian island chain over tens of millions of years. The slow drift of the Pacific Plate will eventually carry Mauna Loa away from the hotspot within 500,000 to one years from now. Mauna Loas most recent eruption occurred from March 24 to April 15,1984, no recent eruptions of the volcano have caused fatalities, but eruptions in 1926 and 1950 destroyed villages, and the city of Hilo is partly built on lava flows from the late 19th century. Because of the hazards it poses to population centers, Mauna Loa is part of the Decade Volcanoes program. Mauna Loa has been monitored intensively by the Hawaiian Volcano Observatory since 1912, observations of the atmosphere are undertaken at the Mauna Loa Observatory, and of the Sun at the Mauna Loa Solar Observatory, both located near the mountains summit. Hawaii Volcanoes National Park covers the summit and the flank of the volcano, and also incorporates Kīlauea. Like all Hawaiian volcanoes, Mauna Loa was created as the Pacific tectonic plate moved over the Hawaiian hotspot in the Earths underlying mantle. The Hawaii island volcanoes are the most recent evidence of this process that, the prevailing view states that the hotspot has been largely stationary within the planets mantle for much, if not all of the Cenozoic Era. However, while the Hawaiian mantle plume is well-understood and extensively studied, Mauna Loa is one of five subaerial volcanoes that make up the island of Hawaiʻi, created by the Hawaii hotspot. The oldest volcano on the island, Kohala, is more than a years old, and Kīlauea. Lōʻihi Seamount on the flank is even younger, but has yet to breach the surface. Since then, the volcano has remained active, with a history of effusive and explosive eruptions, although Mauna Loas activity has been overshadowed in recent years by that of its neighbor Kīlauea, it remains active. Mauna Loa is the largest subaerial and second largest overall volcano in the world, covering an area of 5,271 km2. Consisting of approximately 65,000 to 80,000 km3 of solid rock, the shield-stage lavas that built the enormous main mass of the mountain are tholeiitic basalts, like those of Mauna Kea, created through the mixing of primary magma and subducted oceanic crust. Mokuʻāweoweos caldera floor lies between 170 and 50 m beneath its rim and it is only the latest of several calderas that have formed and reformed over the volcanos life, additionally, two smaller pit craters lie southwest of the caldera, named Lua Hou and Lua Hohonu
Mauna Loa
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Mauna Loa as seen from the air;
Hualālai is visible in the background
Mauna Loa
Mauna Loa
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Landsat mosaic; recent lava flows appear in black
Mauna Loa
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Mauna Loa's summit, overlaid with 100 m (328 ft)
contour lines; its rift zones are visible from the air.
