Subj : Wx Terms (A)(2) To : All From : Daryl Stout Date : Sun Sep 03 2017 10:39 am Adiabatic Changes in temperature caused by the expansion (cooling) or compression (warming) of a body of air as it rises or descends in the atmosphere, with no exchange of heat with the surrounding air. Adiabatic Lapse Rate The rate of decrease of temperature experienced by a parcel of air when it is lifted in the atmosphere under the restriction that it cannot exchange heat with its environment. For parcels that remain unsaturated during lifting, the (dry adiabatic) lapse rate is 9.8ø C per kilometer. Adiabatic Process A process which occurs with no exchange of heat between a system and its environment. Adirondack Type Snow Sampling Set In hydrologic terms, a snow sampler consisting of a 5-foot fiberglass tube, 3 inches in diameter, with a serrated-edge steel cutter at one end and a twisting handle at the other. This sampler has a 60-inch snow depth capacity. ADJ Adjacent ADPC Acoustic Doppler Current Profiler ADVCTN Advection- Transport of an atmospheric property by the wind. Advection (Abbrev. ADVCTN)- Transport of an atmospheric property by the wind. Advection Fog A fog that forms when warm air flows over a cold surface and cools from below until saturation is reached. ADVIS In hydrologic terms, a program which combines the Antecedent Precipitation Index (API) method of estimating runoff with unit hydrograph theory to estimate streamflow for a headwater basin. Advisory (Abbrev. ADVY)- Highlights special weather conditions that are less serious than a warning. They are for events that may cause significant inconvenience, and if caution is not exercised, it could lead to situations that may threaten life and/or property. ADVN Advance ADVY Advisory - Highlights special weather conditions that are less serious than a warning. They are for events that may cause significant inconvenience, and if caution is not exercised, it could lead to situations that may threaten life and/or property. Aeration Zone A portion of the lithosphere in which the functional interstices of permeable rock or earth are not filled with water under hydrostatic pressure. The interstices either are not filled with water or are filled with water that is no held by capillarity. Aeroallergens Any of a variety of allergens such as pollens, grasses, or dust carried by winds. Aerosol A system of colloidal particles dispersed in a gas, such as smoke or fog. AFCT Affect AFD Area Forecast Discussion - This National Weather Service product is intended to provide a well-reasoned discussion of the meteorological thinking which went into the preparation of the Zone Forecast Product. The forecaster will try to focus on the most particular challenges of the forecast. The text will be written in plain language or in proper contractions. At the end of the discussion, there will be a list of all advisories, non-convective watches, and non-convective warnings. The term non-convective refers to weather that is not caused by thunderstorms. An intermediate Area Forecast Discussion will be issued when either significant forecast updates are being made or if interesting weather is expected to occur. AFOS Automation of Field Operations and Services. Computer system linking NWS offices for the transmission of weather data. This system was installed in the early to mid 1980s and it is being replaced by Advanced Weather Interactive Processing System (AWIPS). AFRED Abbreviation for the A Index for Fredericksburg. AFSS Automated Flight Service Station AFT After Afterbay In hydrologic terms, the tail race of a hydroelectric power plant at the outlet of the turbines. The term may be applied to a short stretch of stream or conduit, or to a pond or reservoir. AFTN Afternoon AFTR after AFWA Air Force Weather Agency AGDISP A particular atmospheric disperison model used for treating the transport and diffusion of aerially sprayed pest control agents in agricultural applications. AGFS Aviation Gridded Forecast System Agglomerate An ice cover of floe formed by the freezing together of various forms of ice. AGL Above Ground Level AGN Again AHD Ahead AHOS Automatic Hydrologic Observing System AHOS-S Automatic Hydrologic Observing System - Satellite AHOS-T Automatic Hydrologic Observing System - Telephone Air The mixture of gases comprising the earth's atmosphere. Air Mass A body of air covering a relatively wide area and exhibiting horizontally uniform properties. Air Mass Thunderstorm Generally, a thunderstorm not associated with a front or other type of synoptic-scale forcing mechanism. Air mass thunderstorms typically are associated with warm, humid air in the summer months; they develop during the afternoon in response to insolation, and dissipate rather quickly after sunset. They generally are less likely to be severe than other types of thunderstorms, but they still are capable of producing downbursts, brief heavy rain, and (in extreme cases) hail over 3/4 inch in diameter. Since all thunderstorms are associated with some type of forcing mechanism, synoptic-scale or otherwise, the existence of true air-mass thunderstorms is debatable. Air Pollutant Harmful substance or product introduced into the atmosphere. Air Pollution Potential The meteorological potential for air pollution problems, considered without regard to the presence or absence of actual pollution sources. Air Quality Model Mathematical or conceptual model used to estimate present or future air quality. Air Stagnation A meteorological situation in which there is a major buildup of air pollution in the atmosphere. This usually occurs when the same air mass is parked over the same area for several days. During this time, the light winds cannot "cleanse" the buildup of smoke, dust, gases, and other industrial air pollution. Air Stagnation Advisory This National Weather Service product is issued when major buildups of air pollution, smoke, dust, or industrial gases are expected near the ground for a period of time. This usually results from a stagnant high pressure system with weak winds being unable to bring in fresh air. --- þ Synchronet þ The Thunderbolt BBS - wx1der.dyndns.org .