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Haines Index
Haines Index (also known as Lower Atmosphere Severity Index) is a weather index developed by meteorologist Donald Haines in 1988 that measures the potential for dry, unstable air to contribute to the development of large or erratic wildland fires. The index is derived from the stability (temperature difference between different levels of the atmosphere) and moisture content (dew point depression) of the lower atmosphere. These data may be acquired with a radiosonde or simulated by a numerical weather prediction model. The index is calculated over three ranges of atmospheric pressure: low elevation (950-850 millibars (mb)), mid elevation (850-700 mb), and high elevation (700-500 mb). A Haines Index of 6 means a high potential for an existing fire to become large or exhibit erratic fire behavior, 5 means medium potential, 4 means low potential, and anything less than 4 means very low potential. References See also * Forest fire weather index * Wildfire modeling In computati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorologist
A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists in research, while those using mathematical models and knowledge to prepare daily weather forecasts are called ''weather forecasters'' or ''operational meteorologists''. Meteorologists work in government agencies, private consulting and research services, industrial enterprises, utilities, radio and television stations, and in education. They are not to be confused with weather presenters, who present the weather forecast in the media and range in training from journalists having just minimal training in meteorology to full fledged meteorologists. Description Meteorologists study the Earth's atmosphere and its interactions with the Earth's surface, the oceans and the biosphere. Their knowledge of applied mathematics and physics allows them to understand the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dew Point Depression
The dew point depression (T-Td) is the difference between the temperature and dew point temperature at a certain height in the atmosphere. For a constant temperature, the smaller the difference, the more moisture there is, and the higher the relative humidity. In the lower troposphere, more moisture (small dew point depression) results in lower cloud bases and lifted condensation levels (LCL). LCL height is an important factor modulating severe thunderstorms. One example concerns tornadogenesis, with tornadoes most likely if the dew point depression is 20 °F (11 °C) or less, and the likelihood of large, intense tornadoes increasing as dew point depression decreases. LCL height also factors in downburst and microburst activity. Conversely, instability is increased when there is a mid-level dry layer (large dew point depression) known as a " dry punch", which is favorable for convection if the lower layer is buoyant. As it measures moisture content in the atmosphere, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmosphere
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosphere is the outer region of a star, which includes the layers above the opaque photosphere; stars of low temperature might have outer atmospheres containing compound molecules. The atmosphere of Earth is composed of nitrogen (78%), oxygen (21%), argon (0.9%), carbon dioxide (0.04%) and trace gases. Most organisms use oxygen for respiration; lightning and bacteria perform nitrogen fixation to produce ammonia that is used to make nucleotides and amino acids; plants, algae, and cyanobacteria use carbon dioxide for photosynthesis. The layered composition of the atmosphere minimises the harmful effects of sunlight, ultraviolet radiation, the solar wind, and cosmic rays to protect organisms from genetic damage. The current comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiosonde
A radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calculate the following variables: altitude, pressure, temperature, relative humidity, wind (both wind speed and wind direction), cosmic ray readings at high altitude and geographical position (latitude/longitude). Radiosondes measuring ozone concentration are known as ozonesondes. Radiosondes may operate at a radio frequency of 403 MHz or 1680 MHz. A radiosonde whose position is tracked as it ascends to give wind speed and direction information is called a rawinsonde ("radar wind -sonde"). Most radiosondes have radar reflectors and are technically rawinsondes. A radiosonde that is dropped from an airplane and falls, rather than being carried by a balloon is called a dropsonde. Radiosondes are an essential source of meteorological data ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bar (unit)
The bar is a metric unit of pressure, but not part of the International System of Units (SI). It is defined as exactly equal to 100,000 Pa (100 kPa), or slightly less than the current average atmospheric pressure on Earth at sea level (approximately 1.013 bar). By the barometric formula, 1 bar is roughly the atmospheric pressure on Earth at an altitude of 111 metres at 15 °C. The bar and the millibar were introduced by the Norwegian meteorologist Vilhelm Bjerknes, who was a founder of the modern practice of weather forecasting. The International System of Units, despite previously mentioning the bar, now omits any mention of it.. The bar has been legally recognised in countries of the European Union since 2004.British Standard BS 350:2004 ''Conversion Factors for Units''. The US National Institute of Standards and Technology (NIST) deprecates its use except for "limited use in meteorology" and lists it as one of several units that "must not be introduced ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forest Fire Weather Index
The Forest fire weather index (FWI) (French: indice forêt météo, IFM) is an estimation of the risk of wildfire computed by Météo France and the Meteorological Service of Canada. It was introduced in France in 1992 but is based on a Canadian empirical model developed and widely used since 1976. Description The index is a whole number that ranges between 0 and 20 in France and up to above 30 in Canada. It is computed from five components. The first three components are numeric ratings of the moisture content of litter and other fine fuels, the average moisture content of loosely compacted organic layers of moderate depth, and the average moisture content of deep, compact organic layers. The last two components are the rate of fire spread if fuel is available for combustion, and the frontal fire intensity. The essential information needed to calculate this index is: * the humidity of the air at the beginning of the afternoon (when it has its lowest value); * the temperature in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wildfire Modeling
In computational science, wildfire modeling is concerned with numerical simulation of wildland fires in order to understand and predict fire behavior. Wildfire modeling can ultimately aid wildland fire suppression, namely increase safety of firefighters and the public, reduce risk, and minimize damage. Wildfire modeling can also aid in protecting ecosystems, watersheds, and air quality. Objectives Wildfire modeling attempts to reproduce fire behavior, such as how quickly the fire spreads, in which direction, how much heat it generates. A key input to behavior modeling is the Fuel Model, or type of fuel, through which the fire is burning. Behavior modeling can also include whether the fire transitions from the surface (a "surface fire") to the tree crowns (a "crown fire"), as well as extreme fire behavior including rapid rates of spread, fire whirls, and tall well-developed convection columns. Fire modeling also attempts to estimate fire effects, such as the ecological and hydrol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hazard Scales
A hazard is a potential source of harm. Substances, events, or circumstances can constitute hazards when their nature would allow them, even just theoretically, to cause damage to health, life, property, or any other interest of value. The probability of that harm being realized in a specific ''incident'', combined with the magnitude of potential harm, make up its risk, a term often used synonymously in colloquial speech. Hazards can be classified in several ways; they can be classified as Natural hazard, natural, Anthropogenic hazard, anthropogenic, technological, or any combination, such as in the case of the natural phenomenon of wildfire becoming more common due to human-made climate change or more harmful due to changes in building practices. A common theme across many forms of hazards in the presence of Potential energy, stored energy that, when released, can cause damage. The stored energy can occur in many forms: chemical, mechanical, thermal hazards and by the populations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorological Indices
Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not begin until the 18th century. The 19th century saw modest progress in the field after weather observation networks were formed across broad regions. Prior attempts at prediction of weather depended on historical data. It was not until after the elucidation of the laws of physics, and more particularly in the latter half of the 20th century the development of the computer (allowing for the automated solution of a great many modelling equations) that significant breakthroughs in weather forecasting were achieved. An important branch of weather forecasting is marine weather forecasting as it relates to maritime and coastal safety, in which weather effects also include atmospheric interactions with large bodies of water. Meteorological phenom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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