| Label | Concept definition | Figure(s) | Code |
|---|---|---|---|
| ICE | Frozen <WATER>; ice [SOED, "ice", 1.a]. | 546 | |
| ICE_BOOM | A floating <BARRIER> constrained by <ANCHOR>s and used to deflect the path of floating <ICE> in order to prevent the obstruction of <HYDROGRAPHIC_LOCK>s or <WATER_INTAKE>s or to prevent damage to <BRIDGE_PIER>s or other <STRUCTURE>s; ice boom. | 547 | |
| ICE_CLIFF | A perpendicular or steep face of a <GLACIER> or <ICE_SHELF> of considerable <<HEIGHT>>; ice cliff. | 548 | |
| ICE_FIELD | A <FROZEN_PRECIPITATION_FIELD> that consists of <ICE>; ice-field. | 549 | |
| ICE_GLAZE | A coating of <ICE>, generally clear and smooth, formed on exposed <OBJECT>s by the freezing of a film of supercooled <WATER> deposited by <RAIN>, <DRIZZLE>, or <FOG> or possibly condensed from supercooled water vapour; ice glaze. <ICE_GLAZE> is denser, harder, and more transparent than either <RIME> or <HOAR_FROST>. | 550 | |
| ICE_KEEL | An irregular, linear, downward extension of <ICE> formed where two moving masses of <ICE> collide on a <WATERBODY>; ice keel. | 551 | |
| ICE_PEAK | A rocky peak that may be perpetually covered with <ICE> and that projects above a surrounding <ICE_FIELD>; ice peak. An ice peak is also known as a nunatak. | 552 | |
| ICE_PELLETS | <SOLID_PRECIPITATION> of transparent or translucent <PARTICLE>s of <ICE> that are spherical or irregular, rarely conical, and that have an <<OUTSIDE_DIAMETER>> of 5 millimetres or less; ice pellets. <SMALL_HAIL> is a form of ice pellets. | 553 | |
| ICE_SHELF | A thick sheet of <ICE> usually of great extent, mostly afloat on a <WATERBODY_SURFACE>, with a level or undulating <SURFACE> and attached to <LAND>; ice shelf. The seaward edge is termed an <ICE_CLIFF> (ice front). | 554 | |
| ICE_SLUDGE | Spongy whitish lumps of <ICE> a few centimetres in <<OUTSIDE_DIAMETER>> that are floating on the <WATERBODY_SURFACE> of a shallow <SEA>; ice sludge. | 555 | |
| ICEBERG | A very large mass of <ICE> floating loose in a <WATERBODY> after becoming detached from a <GLACIER> or <ICE_SHELF>; iceberg [SOED, "iceberg", 2]. | 556 | |
| IFR_REGION | A <REGION> in which IFR should be observed. | 557 | |
| ILS_COMPONENT | An air navigation <COMPONENT> that is essential to the establishment and execution of a precision approach based on an ILS. | 558 | |
| ILS_TERMINAL_COMPONENT | An <ATS_ROUTE_COMPONENT> designated for channelling the flow of air traffic via ILS terminal procedures. | 559 | |
| INCINERATOR | A permanent <STRUCTURE> used for the disposal of waste products by burning; incinerator. | 560 | |
| INDIGENOUS_BURIAL_GROUND | A <CEMETERY> for native peoples, generally without <MEMORIAL_MONUMENT>s; indigenous burial ground. | 561 | |
| INDIGENOUS_PEOPLES_RESERVE | A <TRACT>and associated <STRUCTURE>s set apart specifically for the use of a native people; indigenous peoples reserve. | 562 | |
| INDIVIDUAL_FIGHTING_POSITION | A <FIGHTING_POSITION> designed to accommodate an individual soldier and that soldier's <EQUIPMENT>. | 563 | |
| INDUSTRIAL_BUILDING | A <BUILDING> used for the manufacture of goods or the processing of <MATERIAL>s; industrial building. | 564 | |
| INDUSTRIAL_OVEN | An industrial <STRUCTURE> used for hardening, burning, or heating <MATERIAL>s (for example: grain, meal, clay, or wood); industrial oven. | 565 | |
| INDUSTRIAL_WORKS | The <STRUCTURE>s, <GROUNDS>, and <EQUIPMENT> of a manufacturing <FACILITY>; industrial works. | 566 | |
| INFANTRY_TRENCH | A <MILITARY_TRENCH>, typically integrated into a complex <SYSTEM> of <TERRAIN_OBSTACLE>s, that is used to provide cover, concealment, protected <FIGHTING_POSITION>s, and communications capability for infantry. | 567 | |
| INFRARED_MATERIAL_PROPERTY_SET | A <PROPERTY_SET> describing the infrared properties of the <MATERIAL>s composing an <OBJECT>. | 568 | |
| INLAND_SHORELINE | The <SHORELINE> of an inland <WATERBODY>. | 569 | |
| INLAND_WATER | A <WATERBODY> that either does not experience or only minimally experiences tidal fluctuations; inland water. | 570 | |
| INLAND_WATER_BOTTOM | A bathymetric <REGION> underlying an <INLAND_WATER_SURFACE>; inland water bottom. | 571 | |
| INLAND_WATER_ELEVATION | A <SPOT_ELEVATION> associated with an <INLAND_WATER_SURFACE>. | 572 | |
| INLAND_WATER_SURFACE | The <WATERBODY_SURFACE> of an <INLAND_WATER>. | 573 | |
| INLET | A short, narrow <WATERCOURSE> connecting a <MARINE_BAY> or <LAGOON> with a <SEA>; inlet. | 574 | |
| INS_ALIGNMENT_PAD | A designated <LOCATION> where the automated INS instruments of <AIRCRAFT> are reset before taking-off; INS alignment pad. | 575 | |
| INSECT | An <ARTHROPOD> of the superclass Hexapoda, characterized by having six feet; insect [SOED, "hexopod"]. | 576 | |
| INSTITUTIONAL_FACILITY | A <FACILITY> housing an established organization or foundation, especially one dedicated to education, public service, or culture, that provides for the care of <HUMAN>s who are destitute, disabled, or mentally ill; institutional facility. | 577 | |
| INTEREST_SITE | A <REGION> maintained for the public and declared to be of national or provincial historical significance or interest; interest site. | 578 | |
| INTERIOR_WALL | A <WALL> in a <BUILDING> separating two <ROOM>s from each other; interior wall. | 579 | |
| INTERIOR_WALL_OPENING | An opening (for example: an uncovered <APERTURE> in an <INTERIOR_WALL> and/or the space above a <WALL> of partial <<HEIGHT>>) that supports the passage of <MATERIAL>s or visibility into an adjoining <ROOM>. | 580 | |
| INTERNATIONAL_DATE_LINE | A <LINE> designated as the place on the <EARTH> where each calendar day begins; International Date Line. This <LINE> generally coincides with the 180th meridian but is modified to avoid <LAND>. | 581 | |
| INTERPLANETARY_MAGNETIC_FIELD | The <MAGNETIC_FIELD> in a <STAR_SYSTEM> carried with its <STELLAR_WIND>; interplanetary magnetic field. | 582 | |
| INUNDATED_LAND | <LAND> subject to controlled inundation (for example: flooded by the regulation of the level of a <RESERVOIR>) that is normally associated with permanently flooded ground in which <TREE>s are still standing; inundated land. | 583 | |
| INVERTEBRATE | An <ANIMAL> without a backbone or spinal column that does not belong to the subphylum Vertebrata; invertebrate [SOED, "invertebrate"]. | 584 | |
| IONOSPHERE | The <ATMOSPHERE_REGION> of the <EARTH> characterized by ions and free electrons existing in sufficient quantities to reflect electromagnetic waves and located roughly between the <<ALTITUDE_MSL>>s of 70 to 500 kilometres; ionosphere. | 585 | |
| IONOSPHERE_ELECTRON_DENSITY- _PROPERTY_SET |
A <PROPERTY_SET> describing the electron-density related characteristics of an <IONOSPHERE>. | 586 | |
| IONOSPHERE_SCINTILLATION- _PROPERTY_SET |
A <PROPERTY_SET> describing the distortion of the propagation of electromagnetic radiation through an <IONOSPHERE> due to medium density irregularities; ionosphere scintillation property set. | 587 | |
| IONOSPHERIC_D_REGION | The lowest daytime <REGION> of the <IONOSPHERE> characterized by weak concentrations of ions and located roughly between the <<ALTITUDE_MSL>>s of 50 and 90 kilometres; ionospheric D-region. An ionospheric D-region is also known as an ionospheric D-layer. | 588 | |
| IONOSPHERIC_E_REGION | A daytime <REGION> of the <IONOSPHERE> characterized by concentrations of O2+ and NO+ ions and located roughly between the <<ALTITUDE_MSL>> s of 85 and 140 kilometres; ionospheric E-region. An ionospheric E-region is also known as an ionospheric E-layer. | 589 | |
| IONOSPHERIC_F1_REGION | A daytime <REGION> of the <IONOSPHERE>, above the <IONOSPHERIC_E_REGION>, characterized by weak concentrations of O2+ ions and located roughly between the <<ALTITUDE_MSL>>s of 120 and 200 kilometres; ionospheric F1-region. An ionospheric F1-region is also known as an ionospheric F1-layer. | 590 | |
| IONOSPHERIC_F2_REGION | A daytime <REGION> of the <IONOSPHERE>, above the <IONOSPHERIC_E_REGION>, characterized by weak concentrations of O2+ ions and located roughly between the <<ALTITUDE_MSL>>s of 200 and 1 500 kilometres; ionospheric F2-region. An ionospheric F2-region is also known as an ionospheric F2-layer. | 591 | |
| IRRIGATION_DITCH | A <TRENCH> that is constructed for the purpose of irrigation or drainage; irrigation ditch. | 592 | |
| ISLAND | A <TRACT> smaller (usually much smaller) than a continent and surrounded by a <WATERBODY>; island. | 593 | |
| ISOGONIC_LINE | An <ISOPLETH> that connects <LOCATION>s of equal magnetic variation; isogonic line. | 594 | |
| ISOPLETH | A <LINE> defined by <LOCATION>s for which some chosen quantity has the same value; isopleth [SOED, "isopleth", 1]. | 595 | |
| ISTHMUS | A <TERRAIN_STRIP> that is bordered on both sides by <WATERBODY>s and that connects two larger bodies of <LAND>; isthmus. | 596 |
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