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Alpine Planetary Boundary Layer
The alpine planetary boundary layer is the planetary boundary layer (PBL) associated with mountainous regions. Due to its high spatial and temporal variability, its behavior is more complex than over a flat terrain. The fast changing local wind system directly linked to topography and the variable land cover that goes from snow to vegetation have a significant effect on the growth of the PBL and make it much harder to predict. Understanding the processes inducing changes in the mountain PBL have critical applications for predicting air pollution transport, fire weather and local intense thunderstorm events. While some processes, such as Lee wave, mountain waves, have been well studied in the mountain PBL due to their importance for aviation, most of the behaviors of the alpine PBL are relatively unknown. Wind systems The PBL in complex terrain is shaped by three local (non synoptic) wind systems occurring at different scales, which are closely related to the structure of the topo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shade (shadow)
Shade is the blocking of sunlight (in particular direct sunshine) by any object, and also the shadow created by that object. Shade also consists of the colors grey, black, white, etc. It may refer to blocking of sunlight by a roof, a tree, an umbrella, a window shade or blind, curtains, or other objects. As a resource In temperate and tropical zones (most places on Earth), shade is an important issue in providing cooling and shelter from harmful heat and ultraviolet emitted by the Sun. Plants Green plants produce shade by absorbing sunlight to invest as energy in photosynthesis to produce sugar. They also actively transpire, producing an additional cooling effect. In gardening terms, there are various types of shade: *Full sun – more than five hours of direct sun per day. *Part shade – two to five hours of direct sun, or all-day ' (sunlight shining through open trees). *Full shade – less than two hours of direct sun per day... Under a dense forest canopy, light ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forced Convection
Forced convection is a mechanism, or type of transport, in which fluid motion is generated by an external source (like a pump, fan, suction device, etc.). Alongside natural convection, thermal radiation, and thermal conduction it is one of the methods of heat transfer and allows significant amounts of heat energy to be transported very efficiently. Applications This mechanism is found very commonly in everyday life, including central heating, air conditioning, steam turbines, and in many other machines. Forced convection is often encountered by engineers designing or analyzing heat exchangers, pipe flow, and flow over a plate at a different temperature than the stream (the case of a shuttle wing during re-entry, for example). Mixed convection In any forced convection situation, some amount of natural convection is always present whenever there are gravitational forces present (i.e., unless the system is in an inertial frame or free-fall). When the natural convection is not neglig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Down Slope Winds Created By Snowpack
Down most often refers to: * Down, the relative direction opposed to up * Down (gridiron football), in American/Canadian football, a period when one play takes place * Down feather, a soft bird feather used in bedding and clothing * Downland, a type of hill Down may also refer to: Places * County Down, Northern Ireland, UK ** Down (Parliament of Ireland constituency), abolished 1800 ** Down (Northern Ireland Parliament constituencies) ** Down (Northern Ireland Parliament constituency), 1921–1929 ** Down (UK Parliament constituency), 1801–1885 and 1922–1950 ** Down (civil parish) ** Down county football team, Gaelic football * Down, County Westmeath, Ireland * Downe, Greater London, England, formerly called "Down" People * Down (surname) * John Langdon Down (1828–1896), British physician best known for his description of Down syndrome * Down AKA Kilo (born 1985), American rapper Film and television * ''Down'' (film), a 2001 English remake of the film ''De Lift'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth's Atmosphere
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention ( greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation). By mole fraction (i.e., by number of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% Carbon dioxide in Earth's atmosphere, carbon dioxide, and small amounts of other gases. Air also contains a variable amount of Water vapor#Water vapor in Earth's atmosphere, water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere. Air composition, temperature, and atmospheric pressure vary with altitude. Within the atmosphere, air suitable for use in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mountain CBL
A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher than a hill, typically rising at least 300 metres (1,000 feet) above the surrounding land. A few mountains are isolated summits, but most occur in mountain ranges. Mountains are formed through tectonic forces, erosion, or volcanism, which act on time scales of up to tens of millions of years. Once mountain building ceases, mountains are slowly leveled through the action of weathering, through slumping and other forms of mass wasting, as well as through erosion by rivers and glaciers. High elevations on mountains produce colder climates than at sea level at similar latitude. These colder climates strongly affect the ecosystems of mountains: different elevations have different plants and animals. Because of the less hospitable terrain and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diurnal Mountain Winds Variation
Diurnal ("daily") may refer to: General * Diurnal cycle, any pattern that recurs daily ** Diurnality, the behavior of animals and plants that are active in the daytime * Diurnal phase shift, a phase shift of electromagnetic signals * Diurnal temperature variation, a cycle of daily temperature change Astronomy * Diurnal arc, the time (expressed in right ascension) that it takes a planet etc. to move from its rising to its setting point * Diurnal motion, the apparent motion of stars around the Earth Astrology * Diurnal chart, a chart for a given date, based on the natal chart * Diurnal planet, a planet in a sect for which the Sun is above the horizon * Diurnal sign, a sign in the zodiac See also * Diurnality *Salisbury Diurnal George Herbert Palmer ( Grantchester, 9 August 1846 - Oxford, 20 June 1926) was an English Anglo-Catholic priest, musicologist, organist, and expert on plainchant, particularly of the Sarum Use. Named after the priest and poet George Herbert, he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Santa Ana Winds
The Santa Ana winds (sometimes devil winds) "Scholars who have looked into the name's origins generally agree that it derives from Santa Ana Canyon, the portal where the Santa Ana River -- as well as a congested Riverside (CA-91) Freeway -- leaves Riverside County and enters Orange County. When the Santa Anas blow, winds can reach exceptional speeds in this narrow gap between the Puente Hills and Santa Ana Mountains." are strong, extremely dry downslope winds that originate inland and affect coastal Southern California and northern Baja California. They originate from cool, dry high-pressure air masses in the Great Basin. Santa Ana winds are known for the hot, dry weather that they bring in autumn (often the hottest of the year), but they can also arise at other times of the year. They often bring the lowest relative humidities of the year to coastal Southern California, and “beautifully clear skies.” These low humidities, combined with the warm, compressionally-heated a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspect (geography)
In physical geography and physical geology, aspect (also known as exposure) is the compass direction or azimuth that a terrain surface faces. For example, a slope landform on the eastern edge of the Rockies toward the Great Plains is described as having an ''easterly aspect''. A slope which falls down to a deep valley on its western side and a shallower one on its eastern side has a ''westerly aspect'' or is a ''west-facing slope''. The direction a slope faces can affect the physical and biotic features of the slope, known as a slope effect. The term aspect can also be used to describe a related distinct concept: the horizontal alignment of a coastline. Here, the aspect is the direction which the coastline is facing towards the sea. For example, a coastline with sea to the northeast (as in most of Queensland) has a ''northeasterly aspect''. Aspect is complemented by '' grade'' to characterize the surface gradient. Importance Aspect can have a strong influence on tempera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slope Winds
In mathematics, the slope or gradient of a line is a number that describes both the ''direction'' and the ''steepness'' of the line. Slope is often denoted by the letter ''m''; there is no clear answer to the question why the letter ''m'' is used for slope, but its earliest use in English appears in O'Brien (1844) who wrote the equation of a straight line as and it can also be found in Todhunter (1888) who wrote it as "''y'' = ''mx'' + ''c''". Slope is calculated by finding the ratio of the "vertical change" to the "horizontal change" between (any) two distinct points on a line. Sometimes the ratio is expressed as a quotient ("rise over run"), giving the same number for every two distinct points on the same line. A line that is decreasing has a negative "rise". The line may be practical – as set by a road surveyor, or in a diagram that models a road or a roof either as a description or as a plan. The ''steepness'', incline, or grade of a line is measured by the absolute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Boundary Layer
In meteorology, the planetary boundary layer (PBL), also known as the atmospheric boundary layer (ABL) or peplosphere, is the lowest part of the atmosphere and its behaviour is directly influenced by its contact with a planetary surface. On Earth it usually responds to changes in surface radiative forcing in an hour or less. In this layer physical quantities such as flow velocity, temperature, and moisture display rapid fluctuations ( turbulence) and vertical mixing is strong. Above the PBL is the "free atmosphere", where the wind is approximately geostrophic (parallel to the isobars), while within the PBL the wind is affected by surface drag and turns across the isobars (see Ekman layer for more detail). Cause of surface wind gradient Typically, due to aerodynamic drag, there is a wind gradient in the wind flow ~100 meters above the Earth's surface—the surface layer of the planetary boundary layer. Wind speed increases with increasing height above the ground, starti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valley Winds
A valley is an elongated low area often running between Hill, hills or Mountain, mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over a very long period. Some valleys are formed through erosion by glacier, glacial ice. These glaciers may remain present in valleys in high mountains or polar areas. At lower latitudes and altitudes, these glaciation, glacially formed valleys may have been created or enlarged during ice ages but now are ice-free and occupied by streams or rivers. In desert areas, valleys may be entirely dry or carry a watercourse only rarely. In karst, areas of limestone bedrock, dry valleys may also result from drainage now taking place cave, underground rather than at the surface. Rift valleys arise principally from tectonics, earth movements, rather than erosion. Many different types of valleys are described by geographers, using terms th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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