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.
InvestA weather system for which a tropical cyclone forecast center (NHC, CPHC, or JTWC) is interested in collecting specialized data sets (e.g.
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.
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
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.
IrreversibilitiesChanges that, once set in motion, cannot be reversed, at least on human time scales.
IrrigationThe controlled application of water for agricultural purposes through manmade systems to supply water requirements that are not satisfied by rainfall.
Irrigation RequirementQuantity of water, exclusive of effective precipitation, that is required for crop production. See crop irrigation requirement.
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.
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…
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…
IsodopA contour of constant Doppler velocity values.
IsodrosothermA line connecting points of equal dew point temperature.
IsoheightSame as a contour depicting vertical height of some surface above a datum plane.
IsohelA line on a weather map connecting points receiving equal sunlight.
IsohyetA line that connects points of equal rainfall.
IsoplethA broad term for any line on a weather map connecting points with equal values of a particular atmospheric variable (temperature, dew point, etc.).
IsotachA line connecting points of equal wind speed.
IsothermA line connecting points of equal temperature.
isotope(I-soh-tope) A form of a chemical element in which the atoms have the same number of protons (part of the nucleus of an atom) but with a different number…
Isotropicthe property of being independent of direction. Isotropic radiation has the same intensity regardless of the direction of measurement.
ITCZInter-tropical Convergence Zone. The region where the northeasterly and southeasterly tradewinds converge, forming an often continuous band of clouds or…