<descriptor thcode="2"><thesaurus thcode="2" name="USGS Thesaurus" scope="Topics and methods of scientific study carried out by USGS, with product types, scientific disciplines, geologic time, and types of institutional structure and activities.  Broad and shallow, used to help people find scientific information." creator="U.S. Geological Survey" rights="Public domain" edition="2.0" date="2020-01-09" codetype="number" prefix="topic" uri="https://www2.usgs.gov/science/USGSThesaurus" tblname="term" nonpref="nonpref" relterm="relterm" root_code="1" contact="pschweitzer"><category><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/></category><altlabel><altlabel>USGSThesaurus</altlabel><altlabel>USGSThesaurus</altlabel></altlabel></thesaurus><term thcode="2" code="731" name="meteorology" parent="68" scope="Branch of science dealing with the short-term variations of atmospheric conditions including wind, precipitation, temperature, humidity, cloud cover, and air pressure."/><bt><term thcode="2" code="68" name="atmospheric sciences" parent="291" scope="Studies relating to composition, structure, physics, chemistry, and dynamics of the atmosphere."/><term thcode="2" code="291" name="earth sciences" parent="1019" scope="Broad term for all science related to the study of the earth."/><term thcode="2" code="1019" name="sciences" parent="1" scope="Major educational fields, fields of study, and professional groupings within USGS."/><term thcode="2" code="1" name="Categories" scope="Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."/></bt><rt><term thcode="2" code="63" name="atmospheric and climatic processes" parent="101" scope="Phenomena affecting or occurring within the mass of gases that surrounds the earth, including its physics, chemistry, dynamics, and weather conditions."/><term thcode="2" code="170" name="climatology" parent="68" scope="Scientific study of the characteristic weather conditions of geographic areas."/><term thcode="2" code="549" name="hurricanes" parent="1102" scope="Severe cyclones, or revolving storms, originating over the equatorial regions of the earth, accompanied by torrential rain, lightning, and winds with a speed greater than 74 miles per hour."/><term thcode="2" code="560" name="hydrology" parent="291" scope="Branch of earth science that deals with water as it occurs in the atmosphere, on the surface of the ground, and underground."/><term thcode="2" code="814" name="ocean currents" parent="816" scope="Recurrent strong flows of seawater generated by wind or variations in water density along a given path."/><term thcode="2" code="818" name="ocean sciences" parent="291" scope="Sciences involved in the study of geological, biological, chemical, and physical characteristics and processes of the oceans."/><term thcode="2" code="901" name="planetary sciences" parent="1019" scope="Scientific study of the solid bodies of the solar system, including planets, moons, asteroids, meteorites, and interplanetary materials."/><term thcode="2" code="1102" name="storms" parent="63" scope="Atmospheric disturbances with winds of unusual force or direction. Accompanied by rain, snow, hail, or sleet, and often by thunder and lightning."/><term thcode="2" code="1178" name="tornadoes" parent="1102" scope="Violent storms characterized by whirling funnels of wind moving at great speeds."/></rt></descriptor>