Diffuse Solar RadiationSunlight scattered by atmospheric particles and gases so that it arrives at the earth's surface from all directions and can not be focused.
diffuse spectral irradianceThe narrow spectral range of measurements coming directly from the sky except for solar radiation coming directly from the sun whose wavelength falls…
diffusionThe spontaneous movement of molecules from a region of higher concentration to a region of lower concentration.
Diffusion LengthThe mean distance a free electron or hole moves before recombining with another hole or electron.
Difluence(or diffluence) - A pattern of wind flow in which air moves outward (in a "fan-out" pattern) away from a central axis that is oriented parallel to the…
digestTo cut DNA molecules with one or more restriction endonucleases.
DigesterAn airtight vessel or enclosure in which bacteria decomposes biomass in water to produce biogas.
Digester (Anaerobic)A device in which organic material is biochemically decomposed (digested) by anaerobic bacteria to treat the material and/or to produce biogas.
digitizerDevice that converts analog information into a digital format; for flat graphic material, such as maps, a digitizer can either be flatbed or scanning.
dihaploidAn individual which arises from a doubled haploid.
dihybridAn individual that is heterozygous for two pairs of alleles; the progeny of a cross between homozygous parents differing at two loci.
DikeA low embankment, usually constructed to close up low areas of the reservoir rim and thus limit the extent of the reservoir.
DilatancyThe expansion of cohesionless soils when subject to shear deformation.
DilutionDilution occurs when a company issues additional shares of stock, and as a result the earnings per share and the book value per share decline.
dimer1. A molecule formed by the covalent combination of two monomers, generally accompanied by elimination of water. 2.
dimethyl sulphoxide(Abbreviation: DMSO). A highly hygroscopic liquid and powerful solvent with little odour, colour or toxicity when pure.
DimmerA light control device that allows light levels to be manually adjusted. A dimmer can save energy by reducing the amount of power delivered to the light…
dimorphismThe existence of two distinctly different types of individuals within a species. An obvious example is sexual dimorphism in mammals.
DiodeAn electronic device that allows current to flow in one direction only.
dioeciousA plant species in which male and female flowers form on different plants.
DioriteA coarse-grained intrusive (or plutonic) igneous rock, less mafic than gabbro, but more mafic than granite and granodiorite; the plutonic equivalent of…
DioxinA family of compounds, some of which are hazardous, that result from combustion of carbon materials.
DipThe angle that a planar geologic surface, for example, a fault, is inclined from the horizontal.
Dip TubeA tube inside a domestic water heater that distributes the cold water from the cold water supply line into the lower area of the water heater where…
diplonemaStage in prophase I of meiosis following the pachytene stage, but preceding diakinesis, in which one pair of sister chromatids begin to separate from the…
DIR1. Direction 2. On a buoy report, the ten-minute average wind direction measurements in degrees clockwise from true North.
direct accessThe ability of an electric power consumer to purchase electricity from a supplier of their choice without being physically inhibited by the owner of the…
Direct CurrentA type of electricity transmission and distribution by which electricity flows in one direction through the conductor; usually relatively low voltage and…
Direct current (DC)(DC)A steady current that flows in one direction only. The current from batteries is an example of direct current.
Direct effectsEffects on the environment which occur at the same time and place as the initial cause or action.
direct embryogenesisThe formation in culture, on the surface of zygotic or somatic embryos or on explant tissues (leaf section, root tip, etc.
Direct Flood DamageThe damage done to property, structures, goods, etc., by a flood as measured by the cost of replacement and repairs.
Direct HitA close approach of a tropical cyclone to a particular location. For locations on the left-hand side of a tropical cyclone's track (looking in the…
Direct impactsImpacts occurring at the place of origin and at the time of the proposed activity.
direct insolationThe solar radiation that is transmitted directly through the atmosphere to the earth's surface without interacting with atmospheric components.
Direct Normal Insolation (DNI)(DNI)Sunlight that directly strikes a surface. DNI does not include refracted sunlight that strikes clouds, dust, or the ground first.
direct organogenesisFormation of organs directly on the surface of cultured intact explants . The process does not involve callus formation. Opposite: indirect organogenesis.
direct repeatTwo or more stretches of DNA within a single molecule which have the same nucleotide sequence in the same orientation.
Direct RunoffWater that flows over the ground surface or through the ground directly into streams, rivers, or lakes.
Direct shear testA shear test in which soil or rock under an applied normal load is stressed to failure by moving one section of the specimen container (shear box)…
direct shortwave irradianceRadiant energy, across the wavelength range of 0.4 and 4 µm, that is transferred directly from the sun to the receiver.
Direct Solar RadiationThe component of solar radiation received by the earth's surface only from the direction of the sun's disk (i.e.
Direct Solar Water HeaterThese systems use water as the fluid that is circulated through the collector to the storage tank. Also known as "open-loop" systems.
direct spectral irradianceThe narrow spectral range of measurements coming directly from the sun whose wavelength falls within the solar range of 0.4 and 4 µm.
Direct Vent HeaterA type of combustion heating system in which combustion air is drawn directly from outside and the products of combustion are vented directly outside.
Direct Water HeaterA type of water heater in which heated water is stored within the tank. Hot water is released from the top of the tank when a hot water faucet is turned.
Direct-GainThe process by which sunlight directly enters a building through the windows and is absorbed and stored in massive floors or walls.
directed amplification of minisatellite DNA(Abbreviation: DAMD). A polymerase chain reaction technique used for obtaining molecular markers in the region of minisatellites .
Directed differentiationManipulating stem cell culture conditions to induce differentiation into a particular cell type.
Directed evolutionA laboratory process used on isolated molecules or microbes to cause mutations and identify subsequent adaptations to novel environments.
Directed mutagenesisThe generation of changes in the nucleotide sequence of a cloned gene by one of several procedures.
Directed sequencingSuccessively sequencing DNA from adjacent stretches of chromosome.
Directional cloningDNA insert and vector molecules are digested with two different restriction enzymes to create noncomplementary sticky ends at either end of each…
Directional drillingThe practice of drilling non-vertical wells. Also called slant drilling.
Directional ShearThe component of wind shear which is due to a change in wind direction with height, e.g., southeasterly winds at the surface and southwesterly winds aloft.
disaccharideA dimer consisting of two covalently linked monosaccharides.
disaccharidesThe class of compound sugars that yields two monosaccharide units upon hydrolysis; examples are sucrose, maltose, and lactose.
Disappearing Solar Filament (DSF)In solar-terrestrial terms, the sudden (timescale of minutes to hours) disappearance of a solar filament (prominence).
disarmThe deletion from a plasmid or virus of genes that are pathogenic.
DisasterAn event that demands a crisis response beyond the scope of any single line agency or service (e.g.
Discharge(DIS-charj) In medicine, a fluid that comes out of the body. Discharge can be normal or a sign of disease.
Discharge capacityThe maximum amount of water that can safely released from a given waterway.
Discharge CurveA curve that expresses the relation between the discharge of a stream or open conduit at a given location and the stage or elevation of the liquid surface…
Discharge Table(1) A table showing the relation between two mutually dependant quantities or variable over a given range of magnitude.
discontinuous variationVariation where individuals can be classified as belonging to one of a set of discrete, non-overlapping classes.
discordantMembers of a pair showing different, rather than similar, characteristics.
Discount rateThe discount rate is the interest rate the Federal Reserve charges on loans it makes to banks and other financial institutions.
DiscountingA method of financial and economic analysis used to determine present and future values of investments or expenses.
DisdrometerEquipment that measures and records the size distribution of raindrops.
disease resistanceThe genetically determined ability to prevent the reproduction of a pathogen, thereby remaining healthy.
Disease-associated genesAlleles carrying particular DNA sequences associated with the presence of disease.
disease-freeA plant or animal certified through specific tests as being free of specified pathogens .
disease-indexingDisease-indexed organisms have been assayed for the presence of known diseases according to standard testing procedures.
Dish engineThe dish engine is a concentrating solar power (CSP) technology that produces electricity, typically in the range of 3 to 25 kilowatts, by using a…
disinfectionAttempted elimination by chemical means of internal micro-organisms (particularly pathogens) from a culture or sample; rarely attained. See: sterilize (1).
disinfestationThe elimination or inhibition of the activity of surface-adhering micro-organisms and removal of insects.
disjunctionSeparation of homologous chromosomes during anaphase I of meiosis, or of sister chromatids during anaphase of mitosis and anaphase II of meiosis.
diskThe visible surface of the sun (or any heavenly body) projected against the sky.
Dispatchable power (dispatchability)The ability of a power-producing facility to provide required amounts of power (at or below the facility's nameplate rating) on demand of the grid…
DispatchingTo schedule and control the generation and delivery of electric power.
dispenseThe transfer of a measured volume of a solution.
Dispersing agentAn agent used to assist in separating individual fine soil particles and to prevent them from flocculating when in suspension.
DispersionDistortion of the shape of a seismic-wave train because of variation of velocity with frequency.
DisplacementDisplacement is the replacement of a U.S. worker by an H-1B worker in an essentially equivalent job and occurs within the period beginning 90 days before…
Displacement PowerA source of power (electricity) that can displace power from another source so that source's power can be transmitted to more distant loads.
Displacement pumpReciprocating type of pump where a piston draws water into a closed chamber and then expels it under pressure.