Science — page 9 of 132

Science terms

801. Arctic Circle Arctic Circle The line of latitude 66° 32' N (often taken as 66.5° N). Along this line the Sun does not set on the day of the summer solstice, and does…
802. Arctic front The boundary or front separating deep, cold arctic air from shallower, relatively less cold polar air.
803. Arctic haze Arctic haze Haze in Arctic regions which reduces horizontal and slant visibility and which may extend to a height of about 10 km.
804. Arctic high Arctic high A weak high which appears over the Arctic Basin during late spring, summer and early autumn, one of the centers of action in the atmosphere.
805. Arctic mist Arctic mist A mist of ice crystals; a very light ice fog.
806. Arctic Oscillation (abbrev. AO)- The Arctic Oscillation is a pattern in which atmospheric pressure at polar and middle latitudes fluctuates between negative and positive…
807. Arctic Sea Smoke Steam fog, but often specifically applied to steam fog rising from small open water within sea ice.
808. Arctic tundra A treeless area between the icecap and the tree line of Arctic regions that has permanently frozen subsoil and supports low-growing vegetation such as…
809. Arcus A low, horizontal cloud formation associated with the leading edge of thunderstorm outflow (i.e., the gust front).
810. Area Must have legally defined geographical boundaries, and may be of any size, except that the site must be a subset of the U.S.
811. 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…
812. Area of Influence The area covered by the drawdown curves of a given pumping well or combination of wells at a particular time.
813. Area of influence of a well Area surrounding a well within which the piezometric surface has been lowered when pumping has produced a maximum steady rate of flow.
814. Area of Potential Effect (APE) (APE) The geographic area or areas within which an undertaking (project, activity, program, or practice) may cause changes in the character or use of any…
815. Area Source An array of pollutant sources, so widely dispersed and uniform in strength that they can be treated in a dispersion model as an aggregate pollutant…
816. Area sources (emissions) Any source of air pollution that is released over a relatively small area but which cannot be classified as a point source.
817. Area Wide Hydrologic Prediction System (Abbrev. AWHPS) - A computer system which automatically ingests areal flash flood guidance values and WSR-88D products and displays this data and other…
818. Area Wide Hydrologic Prediction System (AWHPS) (AWHPS) A computer system which automatically ingests areal flash flood guidance values and WSR-88D products and displays this data and other hydrologic…
819. Area-Capacity Curve A graph showing the relation between the surface area of the water in a reservoir, the corresponding volume, and elevation.
820. Area-capacity table A table giving reservoir storage capacity, and sometimes surface areas, in terms of elevation increments.
821. Areas of Critical Environmental Concern (ACEC) (ACEC) These areas are managed by the Bureau of Land Management and are defined by the Federal Land Policy and Management Act of 1976 as having significant…
822. Argon A colorless, odorless inert gas sometimes used in the spaces between the panes in energy efficient windows.
823. Arid A region that receives too little water to support agriculture without irrigation. Less than ten inches of rainfall a year is typically considered arid.
824. ARINC Aeronautical Radio, Incorporated
825. Arizona Water Banking Authority (AWBA) (AWBA) The AWBA was established in 1996 to increase utilization of the state's Colorado River entitlement and to develop long-term storage credits for the state.
826. ARM Climate Research Facility (ACRF) (ACRF) A U.S. Department of Energy designated national user facility that provides a unique asset for the study of global change to the broader national and…
827. ARM Mobile Facility See Mobile Facility.
828. ARMG Abbreviation for antibiotic resistance marker gene.
829. Armoring. See riprap.
830. ARMS Automated Records Management System.
831. ARND Around
832. aromatic (A-ruh-MA-tik) Having an odor, which often is pleasant or spicy.
833. ARP address resolution protocol.
834. ARR Arrive/Arrival
835. ARRA American Recovery and Reinvestment Act (can also be shortened to \"Recovery Act\").
836. Array (Solar) Any number of solar photovoltaic modules or solar thermal collectors or reflectors connected together to provide electrical or thermal energy.
837. Arrayed library Individual primary recombinant clones (hosted in phage, cosmid, YAC, or other vector) that are placed in two-dimensional arrays in microtiter dishes.
838. Arrays See Photovoltaic (PV) array
839. Arroyo A Spanish word for brook that refers to a dry river, creek, or stream bed that temporarily or seasonally fills and flows after sufficient rain.
840. ARS Abbreviation for autonomous(ly) replicating segment (or sequence).
841. ARSI Atmospheric Research System, Inc.
842. ART The Automatic Radiotheodolite. A ground-based radio direction finder that automatically tracks a ballon-borne radiosonde.
843. ARTCC Air Route Traffic Control Center
844. Artesian water (artesian pressure) Groundwater that is under pressure when tapped by a well and is able to rise above the level at which it is first encountered.
845. Artesian Well Water held under pressure in porous rock or soil confined by impermeable geologic formations. An artesian well is free flowing. See confined aquifer.
846. Artifact An object produced or shaped by human beings and of archaeological or historical interest.
847. Artificial Control A weir or other man-made structure which serves as the control for a stream-gaging station.
848. Artificial drains Man-made or constructed drains.
849. artificial inembryonation Non-surgical transfer of embryo(s) to a recipient female. As in vitro embryo technology develops, artificial inembryonation may replace artificial…
850. artificial insemination (Abbreviation: AI). The deposition of semen, using a syringe, at the mouth of the uterus to make conception possible.
851. artificial medium See: culture medium.
852. Artificial recharge Addition of surface water to a ground water reservoir by human activity, such as putting surface water into spreading basins.
853. artificial seed Encapsulated or coated somatic embryos that are planted and treated like seed.
854. artificial selection The practice of choosing individuals from a population for reproduction, usually because these individuals possess one or more desirable traits.
855. ARTS Automated Resources Training System.
856. ARWRI American River Water Resources Investigation.
857. AS assistant secretary.
858. ASA Abbreviation for allele-specific amplification.
859. ASAP as soon as possible.
860. ASAPTRAN The software component of ASAP.
861. ASB Aviation Support Branch
862. ASC Administrative Service Center.
863. ASCC Alaskan System Coordination Council (part of NERC).
864. ASCE American Society of Civil Engineers.
865. ASCII An acronym for American Standard Code that allocates a number to each key on the keyboard and that can be traded and read by most computer systems.
866. ascites (uh-SY-teez) Abnormal buildup of fluid in the abdomen that may cause swelling. In late-stage cancer, tumor cells may be found in the fluid in the abdomen.
867. ASCMP Administrative Support Career Management Program.
868. ascospore One of the spores contained in the ascus of certain fungi.
869. ASCS Agricultural Stabilization and Conservation Service.
870. ascus (pl.: asci) Reproductive sac in the sexual stage of a type of fungi (Ascomycetes) in which ascospores are produced.
871. aseptic Sterile, free of contaminating organisms (bacteria, fungi, algae but not generally including viruses, and particularly not internal symbionts ).
872. asexual Reproduction not involving meiosis or the union of gametes.
873. asexual embryogenesis See: somatic cell embryogenesis.
874. asexual propagation Vegetative, somatic, non-sexual reproduction of a plant without fertilization.
875. Asexual reproduction Nonsexual means of reproduction which can include grafting and budding.
876. Ash The non-combustible residue of a combusted substance composed primarily of alkali and metal oxides.
877. ASHRAE Abbreviation for the American Society of Heating, Refrigeration, and Air-Conditioning Engineers.
878. ASL Above Sea Level
879. ASOS The ASOS program is a joint effort of the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense (DOD).
880. Asphalt A dark-brown-to-black cement-like material containing bitumen as the predominant constituent. It is obtained by petroleum processing.
881. ASR Alkali-silica reaction.
882. ASR-9 Airport Surveillance Radar (FAA)
883. assay (AS-say) A laboratory test to find and measure the amount of a specific substance.
884. ASSE American Society of Safety Engineers.
885. Assembly Putting sequenced fragments of DNA into their correct chromosomal positions.
886. Associated facility A term used by Reclamation to describe those facilities examined by the respective regional or area office.
887. ASSOCIATED PRINCIPAL USER A Principal User with dedicated communications to a WSR-88D unit.
888. Association of Boards of Certification (ABC) An international organization representing over 150 boards which certify the operators of waterworks and waste water facilities.
889. assortative mating Mating in which the partners are chosen on the basis of phenotypic similarity.
890. assortment See: segregation.
891. ASSR alkali-silicate/silica reaction.
892. ASTM Abbreviation for the American Society for Testing and Materials, which is responsible for the issue of many standard methods used in the energy industry.
893. Astrocyte (AS-troh-site) A star-shaped cell that helps nerve cells in the brain and spinal cord work the way they should. An astrocyte is a type of glial cell.
894. Astronomical Dawn The time at which the sun is 18 degrees below the horizon in the morning. Astronomical dawn is that point in time at which the sun starts lightening the…
895. Astronomical Dusk This is the time at which the sun is 18 degrees below the horizon in the evening. At this time the sun no longer illuminates the sky.
896. Astronomical Unit (abbrev. AU)- The mean earth-sun distance, equal to 1.496x1013 cm, or 214.94 solar radii.
897. ASTS above ground storage tanks.
898. Asymmetric Not similar in size, shape, form or arrangement of parts on opposite sides of a line, point or plane.
899. asymmetric hybrid A hybrid formed, usually via protoplast fusion, between two donors, where the chromosome complement of one of the donors is incomplete.
900. asynapsis The failure or partial failure in the pairing of homologous chromosomes during the first meiotic prophase.