Diablo WindSimilar to Santa Ana winds in southern California. These winds occur below canyons in the East Bay hills (Diablo range) and in extreme cases can exceed 60…
DiagnosticAn item that is indicative of a particular time and/or cultural group.
Diagnostic ModelA computer model used to calculate air pollution concentrations. A diagnostic model produces a wind field over an area by interpolating from actual wind…
Diagnostic toolAny artifact which, because of form, shape, or function, provides chronological or manufacturing information.
diakinesisA stage of meiosis at the end of prophase I, in which the contraction of the chromosomes is almost at a maximum, pairing configurations are well defined…
dialysis(dye-AL-ih-sis) The process of filtering the blood when the kidneys are not able to cleanse it.
Diamond DustA fall of non-branched (snow crystals are branched) ice crystals in the form of needles, columns, or plates.
Diaphragm pumpA pump that moves water by reciprocating motion of a diaphragm in a chamber having inlet and outlet check valves.
Diaphragm wallA sheet, thin zone, or facing made of a relatively impervious material such as concrete, steel, wood, plastic, etc. Also see core wall.
Diaphragm-type earthfillAn embankment dam which is constructed mostly of pervious material and having a diaphragm of impermeable material which forms a water barrier.
Diaphragm.(DY-uh-fram) The thin muscle below the lungs and heart that separates the chest from the abdomen.
DiatomSingle-celled or colonial algae whose cell walls are made of silica.
diazotrophAn organism that can fix atmospheric nitrogen.
dichogamyThe condition in which the male and the female reproductive organs of a flower (or certain hermaphroditic animals) mature at different times, thereby…
dicotyledon(Abbreviation: dicot). A plant with two cotyledons . One of the two major classes of flowering plants (along with the monocotyledons ).
Dideoxynucleotide (didN)A deoxynucleotide that lacks a 3' hydroxyl group, and is thus unable to form a 3'-5' phosphodiester bond necessary for chain elongation.
Diesel engineA compression-ignition piston engine in which fuel is ignited by injecting it into air that has been heated (unlike a spark-ignition engine).
Difference of PotentialThe difference in electrical pressure (voltage) between any two points in an electrical system or between any point in an electrical system and the earth.
differential centrifugationA method for separating sub-cellular particles according to their sedimentation coefficients, which are roughly proportional to their size.
Differential compactionMay occur over a large area when the compaction of soil or deeper sediments occurs at different rates and degrees.
differential displayA method to identify mRNAs which are present at different levels in different tissues, or in response to specific treatments.
Differential MotionCloud motion that appears to differ relative to other nearby cloud elements, e.g.
Differential RotationIn solar-terrestrial terms, the change in solar rotation rate with latitude. Low latitudes rotate at a faster angular rate (approx.
Differential ThermostatA type of automatic thermostat (used on solar heating systems) that responds to temperature differences (between collectors and the storage components) so…
differentially permeableReferring to a membrane, through which different substances diffuse at different rates.
DifferentiationIn cancer, refers to how mature (developed) the cancer cells are in a tumor. Differentiated tumor cells resemble normal cells and tend to grow and spread…
Diffuse IcePoorly defined ice edge limiting an area of dispersed ice; usually on the leeward side of an area of floating ice.
diffuse insolationThe solar radiation that is scattered or reflected by atmospheric components (e.g., clouds) to the earth's surface.
diffuse shortwave irradianceAll of the solar radiation, across the wavelength range of 0.4 and 4 µm, coming directly from the sky except for solar radiation coming directly from the…
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)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)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).