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Automatic Meteorological Observing System
The air surrounding and bound to the Earth.
Atmospheric Boundary Layer
Same as Boundary Layer - in general, a layer of air adjacent to a bounding surface. Specifically, the term most often refers to the planetary boundary layer, which is the layer within which the effects of friction are significant. For the earth, this layer is considered to be roughly the lowest one or two kilometers of the atmosphere. It is within this layer that temperatures are most strongly affected by daytime insolation and nighttime radiational cooling, and winds are affected by friction with the earth's surface. The effects of friction die out gradually with height, so the "top" of this layer cannot be defined exactly.
Atmospheric Circulation Model
A mathematical model for quantitatively describing, simulating, and analyzing the structure of the circulation in the atmosphere and the underlying causes. Sometimes referred to as Atmospheric General Circulation Models or AGCMs.
Atmospheric Pressure
The pressure exerted by the earth's atmosphere at any given point, determined by taking the product of the gravitational acceleration at the point and the mass of the unit area column of air above the point.
Atmospheric Radiation
Infrared radiation (energy in the wavelength interval of 3- 80 micrometer) emitted by or being propagated through the atmosphere. It consists of both upwelling and downwelling components. Compare with terrestrial radiation.
In solar-terrestrial terms, the layer of the solar atmosphere above the photosphere and beneath the transition region and the corona.
Chromospheric Events
In solar-terrestrial terms, flares that are just Chromospheric Events without Centimetric Bursts or Ionospheric Effects. (SID) (Class C flare)
Coupled Atmosphere-Ocean Model
Same as Coupled Model; in the context of climate modeling this usually refers to a numerical model which simulates both atmospheric and oceanic motions and temperatures and which takes into account the effects of each component on the other.
Free Atmosphere
The part of the atmosphere that lies above the frictional influence of the earth's surface.
Model Output Statistics - the Hydrometeorological Center (HPC) produces a short range (6 to 60 hours) MOS guidance package generated from the NGM, GFS, and ETA models for over 300 individual stations in the continental United States. These alphanumeric messages are made available at approximately 0400 and 1600 UTC for the 0000 and 1200 UTC forecast cycles, respectively. Model Output Statistics are a set of statistical equations that use model output to forecast the probability of precipitation, high and low temperature, cloud cover, and precipitation amount for many cities across the USA. The statistical equations were specifically tailored for each location, taking into account factors such as each location's climate.
Mostly Clear
When the 1/8th to 2/8ths of the sky is covered by with opaque (not transparent) clouds. Sometimes referred to as Mostly Sunny if this condition is present during daylight hours.
Mostly Cloudy
When the 6/8th to 7/8ths of the sky is covered by with opaque (not transparent) clouds. Same as Considerable Cloudiness.
Mostly Sunny
When the 1/8th to 2/8ths of the sky is covered by with opaque (not transparent) clouds Same as Mostly Clear, except only applicable during daylight hours.
Radar Mosaic
A radar product that combines information from multiple radars to give a regional or national view of reflectivity or precipitation. An individual NEXRAD radar is limited to a range of about 200 miles. Typically, a mosaic product is produced for regions spanning several hundreds to several thousands of miles. Mosaic products are produced by vendors external to the NEXRAD system.
Standard Atmosphere
A hypothetical vertical distribution of atmospheric temperature, pressure, and density that, by international agreement, is taken to be representative of the atmosphere for purposes of pressure altimeter calibrations, aircraft performance calculations, aircraft and missile design, ballistic tables, etc.
The atmospheric shell extending from the top of the mesosphere to outer space. It is a region of more or less steadily increasing temperature with height, starting at 70 or 80 km.

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     Page last Modified: 25 June, 2009 1:01 PM