Science terms starting with B

669 terms

B Abbreviation used on long-term climate outlooks issued by CPC to indicate areas that are likely to be below normal for a given parameter (temperature…
B cell A white blood cell that comes from bone marrow. As part of the immune system, B cells make antibodies and help fight infections. Also called B lymphocyte.
B cells Also known as B lymphocytes. Each B cell is capable of making one specific antibody.
B chromosome A supernumerary chromosome present in some individuals (both plant and animal).
B lymphocyte A white blood cell that comes from bone marrow. As part of the immune system, B lymphocytes make antibodies and help fight infections. Also called B cell.
B-44 Form, Cooperative Station Report A Weather Service form documenting station management, exposure, topography, driving instructions, payment information, hydrometeorologic equipment, and…
B.P. Before present year.
B/C benefit-cost ratio.
B20 A mixture of 20% biodiesel and 80% petroleum diesel based on volume.
BA biological assessment.
BABS Abbreviation for biosynthetic antibody binding sites.
BAC Abbreviation for bacterial artificial chromosome.
Bacillus A rod-shaped bacterium.
Bacillus thuringiensis (Abbreviation: Bt). A bacterium that produces a toxin against certain insects, particularly Coloeoptera and Lepidoptera; a major means of insecticide for…
Bacillus thuringiensis (Bt) A bacterium that kills insects; a major component of the microbial pesticide industry.
Back Door Cold Front A cold front moving south or southwest along the Atlantic seaboard and Great Lakes; these are especially common during the spring months.
back mutation A second mutation at the same site in a gene as the original mutation. The second mutation restores the wild-type protein sequence.
Back pressure A pressure that can cause water to backflow into the water supply when a user's water system is at a higher pressure than the public water system.
Back-building Thunderstorm A thunderstorm in which new development takes place on the upwind side (usually the west or southwest side), such that the storm seems to remain…
Back-sheared Anvil [Slang], a thunderstorm anvil which spreads upwind, against the flow aloft. A back-sheared anvil often implies a very strong updraft and a high severe…
Backcross Crossing an organism with one of its parent organisms.
Backdrafting The flow of air down a flue/chimney and into a house caused by low indoor air pressure that can occur when using several fans or fireplaces and/or if the…
Backfill Material used in refilling excavation, or the process of such refilling. Material used to fill an excavated trench.
Backfill concrete Concrete used in refilling excavation in lieu of earth material.
Backfire A fire started to stop an advancing fire by creating a burned area in its path.
Backflow A reverse flow condition, created by a difference in water pressures, which causes water to flow back into the distribution system.
Backfurrow The first cut of a plow, from which the slice is laid on undisturbed soil.
Background level The average amount of a substance present in the environment. Originally referring to naturally occurring phenomena. Used in toxic substance monitoring.
Background level noise Noise in the environment (other than noise emanating from the source of interest).
Background Radiation Filling all space, e.g. the radiation from the early, hot universe.
Backing Any type of line used to partially fill a reel before the main fishing line is added; commonly used in fly-fishing or by bass anglers who use many of the…
Backing Winds Winds which shift in a counterclockwise direction with time at a given location (e.g.
Backscatter The portion of power scattered back in the incident direction.
backscatter depolarization ratio The ratio of cross polarized to co-polarized elastic backscatter.
backscattered radiation The scattering of radiant energy into the hemisphere of space bounded by a plane normal to the direction of the incident radiation and lying on the same…
Backsight A rod reading taken on a point of known elevation, a benchmark or a turning point.
Backsiphonage A form of backflow caused by a negative or below atmospheric pressure within a water system.
Backup electricity, backup services Power or services needed occasionally; for example, when on-site generation equipment fails.
Backup Energy System A reserve appliance; for example, a stand-by generator for a home or commercial building.
Backup rate A utility charge for providing occasional electricity service to replace on-site generation.
Backwater Shallow area of a river that is sometimes isolated, often being located behind a sand bar or other obstruction in the river.
Backwater Curve The longitudinal profile of the surface of a liquid in a non-uniform flow in an open channel, when the water surface is not parallel to the invert owing…
Backwater Effect The effect which a dam or other obstruction or construction has in raising the surface of the water upstream from it.
Backwater Flooding Upstream flooding caused by downstream conditions such as channel restriction and/ or high flow in a downstream confluence stream.
BACT best available control technology.
Bacteria (bak-TEER-ee-uh) A large group of single-cell microorganisms. Some cause infections and disease in animals and humans.
bacterial artificial chromosome A plasmid vector that can be used to clone large inserts of DNA (up to 500 kb). See: yeast artificial chromosome.
Bacterial artificial chromosome (BAC) Large segments of DNA, 100,000 to 200,000 bases, from another species cloned into bacteria.
bacterial toxin (bak-TEER-ee-ul TOK-sin) A toxic substance, made by bacteria, that can be modified to kill specific tumor cells without harming normal cells.
Bacteriocide A class of antibiotics that kills bacterial cells.
bacteriocin A protein produced by bacteria of one strain and active against those of a closely related strain.
Bacteriophage (Abbreviation: phage). A virus that infects bacteria. Altered forms are used as cloning vectors. See: lambda phage, M13.
Bacteriophage (phage or phage particle) A virus that in- fects bacteria. Altered forms are used as vectors for cloning DNA.
Bacteriostat A class of antibiotics that prevents growth of bacterial cells.
Bacterium More than one bacteria.
baculovirus A class of insect virus used to make DNA cloning vectors for gene expression in eukaryotic cells.
baculovirus expression vector (Abbreviation: BEV). A method for the in vitro production of complex recombinant eukaryotic protein s.
BADA Bay Area Dischargers Association.
Baffle A device, such as a steel plate, used to check, retard, or divert a flow of a material.
Baffle block (dentate) One of a series of upright obstructions designed to dissipate energy as in the case of a stilling basin or drop structure.
Baffle chamber In incinerator design, a chamber designed to settle fly ash and coarse particulate matter by changing the direction and reducing the velocity of the…
Bagasse The fibrous material remaining after the extraction of juice from sugarcane; often burned by sugar mills as a source of energy.
Baghouse An air pollution control device used to filter particulates from waste combustion gases; a chamber containing a bag filter.
Bailer A 10- to 20-foot-long pipe equipped with a valve at the lower end. A bailer is used to remove slurry from the bottom or the side of a well as it is being…
Bajada A broad sloping deposit caused by the joining together of alluvial fans. These occur on the lower slopes of mountains and are often characterized by loose…
Balance Point An outdoor temperature, usually 20 to 45 degrees Fahrenheit, at which a heat pump's output equals the heating demand.
Balance-of-System In a renewable energy system, refers to all components other than the mechanism used to harvest the resource (such as photovoltaic panels or a wind…
Balanced head condition The condition in which the water pressure on the upstream and downstream sides of an object are equal (such as an emergency or regulating gate).
balanced lethal system A system for maintaining a recessive lethal allele at each of two loci on the same pair of chromosomes.
balanced polymorphism Two or more phenotypes maintained in the same breeding population.
Balancing The requirement imposed by electricity grids or natural gas pipelines that supply and demand be equal over a certain time period.
Bald and Golden Eagle Protection Act This Act was originally enacted in 1940 as the Bald Eagle Protection Act to protect bald eagles and later amended to include golden eagles.
Baling A means of reducing the volume of a material by compaction into a bale.
Ball-milling The repeated churning action of cobbles, gravel, and sand caused by the force of water in a stilling basin or other structure by which severe concrete…
Ballast A device used to control the voltage in a fluorescent lamp.
Ballast Efficacy Factor The measure of the efficiency of fluorescent lamp ballasts. It is the relative light output divided by the power input.
Ballast Factor The ratio of light output of a fluorescent lamp operated on a ballast to the light output of a lamp operated on a standard or reference ballast.
BAM Binary Angular Measure
Band Gap In a semiconductor, the energy difference between the highest valence band and the lowest conduction band.
Band Gap Energy The amount of energy (in electron volts) required to free an outer shell electron from its orbit about the nucleus to a free state, and thus promote it…
BANDPASS FILTER A filter whose frequencies are between given upper and lower cutoff values, while substantially attenuating all frequencies outside these values (this…
Bandwidth The amount of information or data that can be sent over a network connection in a given period of time.
Bank America has a "dual banking system" which means that both states and the federal government issue bank charters for the need and convenience of their…
Bank full An established river stage at a given location along a river which is intended to represent the maximum safe water level that will not overflow the river…
Bank Storage Water that has inflitrated from a reservoir into the surrounding land where it remains in storage until water level in the reservoir is lowered.
Bankfull The water level, or stage, at which a stream, river or lake is at the top of its banks and any further rise would result in water moving into the flood…
Bankfull Stage An established river stage at a certain point along a river which is intended to represent the maximum safe water level which will not overflow the river…
Bankfull Stage/Elevation An established river stage/water surface elevation at a given location along a river which is intended to represent the maximum water level that will not…
Banner Cloud A cloud plume often observed to extend downwind behind isolated mountain peaks, even on otherwise cloud-free days.
BAPSU Bay Area Public Service Unit. Public Service section of the San Francisco Bay Area Weather Service Forecast Office.
Bar 1. Historically, the partition separating the general public from the space occupied by the judges, lawyers and other participants in a trial. 2.
bar gene See: pat gene.
Bar screen A screen made of parallel bars set 3/4" to 2" apart used to filter out large objects.
Barber Pole [Slang], a thunderstorm updraft with a visual appearance including cloud striations that are curved in a manner similar to the stripes of a barber pole.
bark The outer protective layer of a tree including the inner bark and the outer bark.
barnase A bacterial ribonuclease, which, when transformed into plants and expressed in the anthers, generates a male sterile phenotype.
Baroclinic leaf shield A cloud pattern on satellite images - frequently noted in advance of formation of a low pressure center.
Baroclinic Zone A region in which a temperature gradient exists on a constant pressure surface.
Baroclinity A measure of the state of stratification in a fluid in which surfaces of constant pressure (isobaric) intersect surfaces of constant density (isosteric).
Barogram An analog record of pressure produced by a barograph