intrageneric crossA hybrid made between parents belonging to two species in the same genus. See: intraspecific cross, interspecific cross.
intragenic complementationOccurs when wild type phenotype is restored in an F1 individual made by crossing two independent mutants, carrying different heteroalleles.
Intraseasonal OscillationOscillation with variability on a timescale less than a season. One example is the Madden-Julian Oscillation.
intraspecificWithin a species, such as an intraspecific cross, or intraspecific variation.
intraspecific crossA hybrid made between parents belonging to the same species. See: intrageneric cross, interspecific cross.
Intravenous(IN-truh-VEE-nus) Into or within a vein. Intravenous usually refers to a way of giving a drug or other substance through a needle or tube inserted into a…
Intrinsic LayerA layer of semiconductor material (as used in a solar photovoltaic device) whose properties are essentially those of the pure, undoped, material.
Intrinsic LuminosityA measure of the true brightness of an object. It is the amount of energy radiated into space every second by a celestial object, such as a star.
IntrogressionBackcrossing of hybrids of two plant populations to introduce new genes into a wild population.
IntronA noncoding DNA sequence within a gene that is initially transcribed into messenger RNA but is later snipped out.
IntrusionA feature (landform, vegetation, or structure) that is generally considered out of context because of excessive contrast and disharmony with…
IntrusiveAn igneous rock that forms under the Earth's surface. Examples include granite, diorite, and gabbro.
InundateTo cover with impounded waters or floodwaters.
InundationThe flooding of normally dry land, primarily caused by severe weather events along the coasts, estuaries, and adjoining rivers.
Inundation AreaArea downstream from a dam that would be subject to flooding in the event of a dam failure or large spillway release. See also, "Flood Plain".
Inundation MapA map delineating the area that would be flooded by a particular flood event. It includes the ground surfaces downstream of a dam showing the probable…
Invasive speciesAny species, including noxious and exotic species, that is an aggressive colonizer and can out-compete indigenous species.
InvasivenessAbility of a plant to spread beyond its introduction site and become established in new locations where it may provide a deliterious effect on organisms…
Inverse Square1 divided by a quantity squared. 1/(r^2). The force due to gravity is proportional to 1 over distance squared. F~1/(d2).
InversionA chromosome re-arrangement, which involves the re-orientation of a segment so that the order of a linear array of genes within it is reversed.
InvertThe lowest point of an underground excavation or the lowest point of the interior of a circular conduit, pipe, or tunnel.
InvertebrateAn animal, such as an insect or mollusk, that lacks a backbone or spinal column.
InvertebratesAll animals without a vertebral column, e.g. spiders, crabs, or worms.
inverted repeatTwo sequences of nucleotides occurring in one strand, where, relative to the first sequence, the second has complementary bases but in the inverted order.
InverterA device that converts direct current electricity (from for example a solar photovoltaic module or array) to alternating current for use directly to…
InvestA weather system for which a tropical cyclone forecast center (NHC, CPHC, or JTWC) is interested in collecting specialized data sets (e.g.
Investor Owned Utility (IOU)A power provider owned by stockholders or other investors; sometimes referred to as a private power provider, in contrast to a public power provider that…
INVRNInversion- Generally, a departure from the usual increase or decrease in an atmospheric property with altitude.
IonAn atom or molecule that has lost or gained one or more electrons and has become electrically charged as a result.
ion channelA protein integral to a cell membrane, through which selective ion transport occurs.
Ion, IonizeAn ion is an atom which has lost or gained one or more electrons so that it has a net electrical charge.
IonizationA process that produces ions, typically collisions between atoms or electrons, or by interaction with electromagnetic radiation.
IonizedThe state in which an atom is missing on or more of its electrons, and is therefore positively charged.
IonizerA device that removes airborne particles from breathable air. Negative ions are produced and give up their negative charge to the particles.
ionizing radiation(I-uh-NYZ-ing RAY-dee-AY-shun) A type of radiation made (or given off ) by x-ray procedures, radioactive substances, rays that enter the Earth's…
IonosphereThe region of Earth's atmosphere that extends from about 50 to 300 miles above the surface of the planet and is made up of multiple layers dominated by…
Ionospheric StormA disturbance in the F region of the ionosphere, which occurs in connection with geomagnetic activity
Iowa vaneA flow deflector that will divert water in a way calculated to attract fish.
IridescenceBrilliant spots or borders of colors in clouds, usually red and green, caused by diffraction of light by small cloud particles.
Iridescent CloudsClouds that exhibit brilliant bright spots, bands, or borders of colors, usually red and green, observed up to about 30 degrees from the sun.
IrradianceThe direct, diffuse, and reflected solar radiation that strikes a surface.
IrradiateApplication of radiation from a source (heat, light, Xrays) to a structure or organism.
irradiation(ih-RAY-dee-AY-shun) The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors.
IrretrievableCommitments that are lost for a period of time.
IrreversibilitiesChanges that, once set in motion, cannot be reversed, at least on human time scales.
IrreversibleCommitments that cannot be reversed, except perhaps in the extreme long term.
Irrigable area not for servicePart of the total irrigable area for which service eventually will be available but for which project facilities have not yet been constructed.
Irrigable landArable land under a specific plan for which a water supply is or can be made available and which is provided with or planned to be provided with…
Irrigated acreageIrrigable acreage actually irrigated in any one year. It includes irrigated cropland harvested, irrigated pasture, cropland planted but not harvested, and…
Irrigated AreaThe gross farm area upon which water is artificially applied for the production of crops, with no reduction for access roads, canals, or farm buildings.
IrrigationThe controlled application of water for agricultural purposes through manmade systems to supply water requirements that are not satisfied by rainfall.
Irrigation checkSmall dike or dam used in the furrow alongside an irrigation border to make the water spread evenly across the border.
Irrigation districtA cooperative, self-governing public corporation set up as a subdivision of the State government, with definite geographic boundaries, organized and…
Irrigation EfficiencyThe ratio of the average depth of irrigation water that is beneficially used to the average depth of irrigation water applied, expressed as a percent.
Irrigation Non-Expansion Area (INA)A geographic area in Arizona that has been designated as having insufficient groundwater to provide a reasonably safe supply for the irrigation of the…
Irrigation RequirementQuantity of water, exclusive of effective precipitation, that is required for crop production. See crop irrigation requirement.
IS elementAbbreviation for insertion sequence element. A short (800-1400 nucleotide pairs) found in bacteria that is capable of transposing to a new genomic…
IsallobarA line of equal change in atmospheric pressure during a specified time period.
Isentropic AnalysisA way in the forecaster can look at the atmosphere in 3-dimensions instead of looking at constant pressure surfaces (such as the 850 mb, 700 mb, 500 mb…
Isentropic LiftLifting of air that is traveling along an upward-sloping isentropic surface. Isentropic lift often is referred to erroneously as overrunning, but more…
Isentropic SurfaceA two-dimensional surface containing points of equal potential temperature.
iso-electric focusing gel(Abbreviation: IEF gel). A variant of gel electrophoresis, in which macromolecules (usually protein s) are separated on the basis of differing…
isoalleleMultiple similar copies of a gene, usually located at independent positions in the genome, which encode similar gene products and produce the same, or a…
Isobaric ChartA weather map representing conditions on a surface of equal atmospheric pressure.
Isobaric ProcessAny thermodynamic change of state of a system that takes a place at constant pressure.
IsobathAn imaginary line on the earth's surface or a line on a map connecting all points which are the same vertical distance above the upper or lower surface of…
IsochromeA curve showing the distribution of the excess hydrostatic pressure at a given time during a process of consolidation.
isochromosomeA chromosome produced following an error in meiosis, in which the two arms are mirror images of each other.
IsochroneA line on a chart connecting equal times of occurrence of an event. In a weather analysis, a sequence plotted on a map of the frontal positions at several…
isodiametricCommonly used to describe cells with equal diameters.
IsodopA contour of constant Doppler velocity values.
IsodrosothermA line connecting points of equal dew point temperature.
IsolatedA National Weather Service convective precipitation descriptor for a 10 percent chance of measurable precipitation (0.01 inch).
Isolated Solar Gain SystemA type of passive solar heating system where heat is collected in one area for use in another.
isolating mechanismThe properties of an organism that prevent interbreeding (and therefore exchange of genetic material) between members of different species that inhabit…
isolation mediumAn optimum plant tissue culture medium suitable for explant survival, growth and development.
isomerOne of two or more compounds that have the same chemical formula but different arrangements of the atoms within the molecules and that may have different…
isomeraseAny of a class of enzymes that catalyse the re-arrangement of the atoms within a molecule, thereby converting one isomer into another.