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Atmospheric pressure, also known as air pressure or barometric pressure, is the pressure within the atmosphere of Earth. The standard atmosphere is a unit of pressure defined as 101,325 Pa (1,013.25 hPa), which is equivalent to 1,013.25 millibars, 760 mm Hg, 29.9212 inches Hg, or 14.696 psi. 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.
A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a bushfire, desert fire, grass fire, hill fire, peat fire, prairie fire, vegetation fire, or veld fire. Some natural forest ecosystems depend on wildfire. Wildfires are distinct from beneficial human usage of wildland fire, called controlled or prescribed burning, although controlled burns can turn into wildfires. Modern forest management often engages in prescribed burns to mitigate risk and promote natural forest cycles.
Geopotential height or geopotential altitude is a vertical coordinate referenced to Earth's mean sea level that represents the work involved in lifting one unit of mass over one unit of length through a hypothetical space in which the acceleration of gravity is assumed constant. In SI units, a geopotential height difference of one meter implies the vertical transport of a parcel of one kilogram; adopting the standard gravity value, it corresponds to a constant work or potential energy difference of 9.80665 joules. Geopotential height differs from geometric height because Earth's gravity is not constant, varying markedly with altitude and latitude; thus, a 1-m geopotential height difference implies a different vertical distance in physical space: "the unit-mass must be lifted higher at the equator than at the pole, if the same amount of work is to be performed". It is a useful concept in meteorology, climatology, and oceanography; it also remains a historical convention in aeronautics as the altitude used for calibration of aircraft barometric altimeters.
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 creates pressure, absorbs most meteoroids and ultraviolet solar radiation, warms the surface through heat retention, allowing life and liquid water to exist on the Earth's surface, and reduces temperature extremes between day and night.
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Numerical weather prediction (NWP) uses mathematical models of the atmosphere and oceans to predict the weather based on current weather conditions. Though first attempted in the 1920s, it was not until the advent of computer simulation in the 1950s that numerical weather predictions produced realistic results. A number of global and regional forecast models are run in different countries worldwide, using current weather observations relayed from radiosondes, weather satellites and other observing systems as inputs.
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National Fire Danger Rating System (NFDRS) is used in the United States to provide a measure of the relative seriousness of burning conditions and threat of wildfires.
Atmospheric instability is a condition where the Earth's atmosphere is considered to be unstable and as a result local weather is highly variable through distance and time. Atmospheric stability is a measure of the atmosphere's tendency to discourage vertical motion, and vertical motion is directly correlated to different types of weather systems and their severity. In unstable conditions, a lifted thing, such as a parcel of air will be warmer than the surrounding air. Because it is warmer, it is less dense and is prone to further ascent.
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WRF-SFIRE is a coupled atmosphere-wildfire model, which combines the Weather Research and Forecasting Model (WRF) with a fire-spread model, implemented by the level-set method. A version from 2010 was released based on the WRF 3.2 as WRF-Fire.
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This glossary of meteorology is a list of terms and concepts relevant to meteorology and atmospheric science, their sub-disciplines, and related fields.
Janice Coen is a Project Scientist at the National Center for Atmospheric Research in Boulder, Colorado. Her work focuses on understanding and predicting wildland fire behavior through the use of wildfire modeling software. She has made major contributions to the field through her coupled weather—wildland fire computer simulation models.
The 2022 California wildfire season was a series of wildfires burning throughout the U.S. state of California. By the end of the year, a total of 7,667 fires had been recorded, totaling approximately 363,939 acres across the state. Wildfires killed nine people in California in 2022, destroyed 772 structures, and damaged another 104. The 2022 season followed the 2020 and 2021 California wildfire seasons, which had the highest and second-highest (respectively) numbers of acres burned in the historical record, with a sharp drop in acreage burned.
References
- ↑ "Haines Index". USA Forest Service. Archived from the original on April 16, 2014. Retrieved 16 April 2014.
- ↑ Noaa
- ↑ Winkler, Julie A.; Potter, Brian E.; Wilhelm, Dwight F.; Shadbolt, Ryan P.; Piromsopa, Krerk; Bian, Xindi (2007). "Climatological and statistical characteristics of the Haines Index for North America". International Journal of Wildland Fire. 16 (2): 139–152. CiteSeerX 10.1.1.486.1768 . doi:10.1071/WF06086.
- ↑ Haines index definition
