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Outline Of Meteorology
The following outline is provided as ''an overview of and topical guide to'' the field of Meteorology. ; Meteorology : The interdisciplinary, scientific study of the Earth's atmosphere with the primary focus being to understand, explain, and forecast weather events. Meteorology, is applied to and employed by a wide variety of diverse fields, including the military, energy production, transport, agriculture, and construction. Essence of meteorology Meteorology * Climate – the average and variations of weather in a region over long periods of time. * Meteorology – the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting (in contrast with climatology). * Weather – the set of all the phenomena in a given atmosphere at a given time. Branches of meteorology *Microscale meteorology – the study of atmospheric phenomena about 1 km or less, smaller than mesoscale, including small and generally fleetin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Pressure
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 760mm Hg, 29.9212 inchesHg, or 14.696psi.International Civil Aviation Organization. ''Manual of the ICAO Standard Atmosphere'', Doc 7488-CD, Third Edition, 1993. . The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, the Earth's atmospheric pressure at sea level is approximately 1 atm. In most circumstances, atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so atmospheric pressure decreases with increasing elevation. Because the atmosphere is thin relative to the Earth's radius—especially the dense atmospheric layer at low altitudes—the Earth's gravi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barograph
A barograph is a barometer that records the barometric pressure over time in graphical form. This instrument is also used to make a continuous recording of atmospheric pressure. The pressure-sensitive element, a partially evacuated metal cylinder, is linked to a pen arm in such a way that the vertical displacement of the pen is proportional to the changes in the atmospheric pressure. Development Alexander Cumming, a watchmaker and mechanic, has a claim to having made the first effective recording barograph in the 1760s using an aneroid cell.Gloria Clifton (2004)"Cumming, Alexander (1731/2–1814)", ''Oxford Dictionary of National Biography'', Oxford University Press. (Subscription or UK public library membership required) Cumming created a series of barometrical clocks, including one for King George III. However, this type of design fell out of favour. Since the amount of movement that can be generated by a single aneroid is minuscule, up to seven aneroids (so called Vidie-cans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anemometer
In meteorology, an anemometer () is a device that measures wind speed and direction. It is a common instrument used in weather stations. The earliest known description of an anemometer was by Italian architect and author Leon Battista Alberti (1404–1472) in 1450. History The anemometer has changed little since its development in the 15th century. Alberti is said to have invented it around 1450. In the ensuing centuries numerous others, including Robert Hooke (1635–1703), developed their own versions, with some mistakenly credited as its inventor. In 1846, John Thomas Romney Robinson (1792–1882) improved the design by using four hemispherical cups and mechanical wheels. In 1926, Canadian meteorologist John Patterson (1872–1956) developed a three-cup anemometer, which was improved by Brevoort and Joiner in 1935. In 1991, Derek Weston added the ability to measure wind direction. In 1994, Andreas Pflitsch developed the sonic anemometer. Velocity anemometers Cup anemomet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Speed
In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Wind speed is now commonly measured with an anemometer. Wind speed affects weather forecasting, aviation and maritime operations, construction projects, growth and metabolism rate of many plant species, and has countless other implications. Note that wind direction is usually almost parallel to isobars (and not perpendicular, as one might expect), due to Earth's rotation. Units Metres per second (m/s) is the SI unit for velocity and the unit recommended by the World Meteorological Organization for reporting wind speeds, and is amongst others used in weather forecasts in the Nordic countries. Since 2010 the International Civil Aviation Organization (ICAO) also recommends meters per second for reporting wind speed when approaching runways, replacing their former recommendation of using kilometres per h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Direction
Wind direction is generally reported by the direction from which it originates. For example, a ''north'' or ''northerly'' wind blows from the north to the south. The exceptions are onshore winds (blowing onto the shore from the water) and offshore winds (blowing off the shore to the water). Wind direction is usually reported in cardinal (or compass) direction, or in degrees. Consequently, a wind blowing from the north has a wind direction referred to as 0° (360°); a wind blowing from the east has a wind direction referred to as 90°, etc. Weather forecasts typically give the direction of the wind along with its speed, for example a "northerly wind at 15 km/h" is a wind blowing ''from'' the north at a speed of 15 km/h. Measurement techniques A variety of instruments can be used to measure wind direction, such as the windsock and wind vane. Both of these instruments work by moving to minimize air resistance. The way a weather vane is pointed by prevailing winds indicates the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Chill
Wind chill or windchill (popularly wind chill factor) is the lowering of body temperature due to the passing-flow of lower-temperature air. Wind chill numbers are always lower than the air temperature for values where the formula is valid. When the apparent temperature is higher than the air temperature, the heat index is used instead. Explanation A surface loses heat through conduction, evaporation, convection, and radiation. The rate of convection depends on both the difference in temperature between the surface and the fluid surrounding it and the velocity of that fluid with respect to the surface. As convection from a warm surface heats the air around it, an insulating boundary layer of warm air forms against the surface. Moving air disrupts this boundary layer, or epiclimate, allowing for cooler air to replace the warm air against the surface. The faster the wind speed, the more readily the surface cools. Alternative approaches Many formulas exist for wind chill beca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Front
A weather front is a boundary separating air masses for which several characteristics differ, such as air density, wind, temperature, and humidity. Disturbed and unstable weather due to these differences often arises along the boundary. For instance, cold fronts can bring bands of thunderstorms and cumulonimbus precipitation or be preceded by squall lines, while warm fronts are usually preceded by stratiform precipitation and fog. In summer, subtler humidity gradients are known as dry lines can trigger severe weather. Some fronts produce no precipitation and little cloudiness, although there is invariably always a wind shift. Cold fronts generally move from west to east, whereas warm fronts move poleward, although any direction is possible. Occluded fronts are a hybrid merge of the two, and stationary fronts are stalled in their motion. Cold fronts and cold occlusions move faster than warm fronts and warm occlusions because the dense air behind them can lift as well as push ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called ''centigrade''), the Fahrenheit scale (°F), and the Kelvin scale (K), the latter being used predominantly for scientific purposes. The kelvin is one of the seven base units in the International System of Units (SI). Absolute zero, i.e., zero kelvin or −273.15 °C, is the lowest point in the thermodynamic temperature scale. Experimentally, it can be approached very closely but not actually reached, as recognized in the third law of thermodynamics. It would be impossible to extract energy as heat from a body at that temperature. Temperature is important in all fields of natur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precipitation (meteorology)
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor (reaching 100% relative humidity), so that the water condenses and "precipitates" or falls. Thus, fog and mist are not precipitation but colloids, because the water vapor does not condense sufficiently to precipitate. Two processes, possibly acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. 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 condense ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-pressure Area
In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible rain or storms), while high-pressure areas are associated with lighter winds and clear skies. Winds circle anti-clockwise around lows in the northern hemisphere, and clockwise in the southern hemisphere, due to opposing Coriolis force, Coriolis forces. Low-pressure systems form under areas of wind divergence that occur in the upper levels of the Atmosphere of Earth, atmosphere (aloft). The formation process of a low-pressure area is known as cyclogenesis. In Meteorology#Dynamic meteorology, meteorology, atmospheric divergence aloft occurs in two kinds of places: * The first is in the area on the east side of upper Trough (meteorology), troughs, which form half of a Rossby wave within the Westerlies (a trough (meteorology), trough with la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frost
Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above-freezing atmosphere coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase change from water vapor (a gas) to ice (a solid) as the water vapor reaches the freezing point. In temperate climates, it most commonly appears on surfaces near the ground as fragile white crystals; in cold climates, it occurs in a greater variety of forms. The propagation of crystal formation occurs by the process of nucleation. The ice crystals of frost form as the result of fractal process development. The depth of frost crystals varies depending on the amount of time they have been accumulating, and the concentration of the water vapor (humidity). Frost crystals may be invisible (black), clear (translucent), or white; if a mass of frost crystals scatters light in all directions, the coating of frost appears white. Types of frost include crystalline frost (hoar fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
