{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/101620"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/101620","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"The effects of entrainment in the developing and rotating stages of supercell thunderstorms","abstract":"Entrainment, the process by which turbulent clouds introduce dry air from outside the cloud inward via overturning eddies at the cloud edge, can decrease the cloud buoyancy, and the water and/or ice mass it contains, limiting both cloud and precipitation development. Numerous studies have shown that growing cumulus clouds entrain air primarily as a result of the overturning thermal circulation near their tops, but have focused upon cumuli in environments with minimal vertical wind shear. Little attention has been given to investigating the entrainment into developing thunderstorms growing in environments with strong vertical wind shear, or to how rotating updrafts in some thunderstorms (i.e. supercells; produced in environments with specific characteristics of the vertical wind shear) might alter the amount of entrainment they experience. In the current study, idealized, 3D, high-resolution numerical simulations of supercell thunderstorms are used to evaluate entrainment and its effects during the developing and rotating stages of the storms. Entrainment is quantified using an algorithm that first estimates the sub-grid scale edge of the 3D cloud core, defined with specific condensate and vertical velocity thresholds, and then calculates the mass flux into that core. As entrainment proceeds in time, the resulting dilution of the core condensate is tracked. Multiple realizations in the same storm environment are created by altering the storm forcing type (heat flux versus “warm bubble”), the horizontal area over which the forcing is applied, and the vertical wind shear. Results show that vertical wind shear can greatly enhance the entrainment rate into the developing storms, being nearly twice as much locally but even exceeding hundreds of percent more when integrated over the entire storm in time. Similar to past studies, the proportionality of entrainment and dilution in the developing stages of the storms depends upon the local properties of the entrained air and the occurrence of multiple thermals. The method of initiating simulated storms with a “warm bubble” was also found to be detrimental to representing the turbulent eddies required for accurate simulations of entrainment, in the developing stages. Surprisingly, entrainment in the rotating stages of the storms decreased slightly but not substantially, counter to theoretical predictions.","abstract_html":"Entrainment, the process by which turbulent clouds introduce dry air from outside the cloud inward via overturning eddies at the cloud edge, can decrease the cloud buoyancy, and the water and/or ice mass it contains, limiting both cloud and precipitation development. Numerous studies have shown that growing cumulus clouds entrain air primarily as a result of the overturning thermal circulation near their tops, but have focused upon cumuli in environments with minimal vertical wind shear. Little attention has been given to investigating the entrainment into developing thunderstorms growing in environments with strong vertical wind shear, or to how rotating updrafts in some thunderstorms (i.e. supercells; produced in environments with specific characteristics of the vertical wind shear) might alter the amount of entrainment they experience. In the current study, idealized, 3D, high-resolution numerical simulations of supercell thunderstorms are used to evaluate entrainment and its effects during the developing and rotating stages of the storms. Entrainment is quantified using an algorithm that first estimates the sub-grid scale edge of the 3D cloud core, defined with specific condensate and vertical velocity thresholds, and then calculates the mass flux into that core. As entrainment proceeds in time, the resulting dilution of the core condensate is tracked. Multiple realizations in the same storm environment are created by altering the storm forcing type (heat flux versus “warm bubble”), the horizontal area over which the forcing is applied, and the vertical wind shear. Results show that vertical wind shear can greatly enhance the entrainment rate into the developing storms, being nearly twice as much locally but even exceeding hundreds of percent more when integrated over the entire storm in time. Similar to past studies, the proportionality of entrainment and dilution in the developing stages of the storms depends upon the local properties of the entrained air and the occurrence of multiple thermals. The method of initiating simulated storms with a “warm bubble” was also found to be detrimental to representing the turbulent eddies required for accurate simulations of entrainment, in the developing stages. Surprisingly, entrainment in the rotating stages of the storms decreased slightly but not substantially, counter to theoretical predictions.","abstract_has_math":false,"creators":["Engelsen, Bryan Nicholas"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Atmospheric Sciences","degree_department":null,"school":null,"contributors":["Lasher-Trapp, Sonia"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-09-27T16:17:59Z","date_published":"2018-09-27T16:17:59Z","updated_at":"2026-07-22T22:24:40Z","subjects":["Entrainment","Supercell","Clouds","Dilution","Thermals","Thunderstorms","Mixing","Rotation","Developing"],"languages":["en"],"rights":["Copyright 2018 Bryan Engelsen"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/101620","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lasher-Trapp, Sonia"]},{"key":"dc:creator","label":"Author","values":["Engelsen, Bryan Nicholas"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-09-27T16:17:59Z","2018-07-19","2018-08"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Atmospheric Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Entrainment","Supercell","Clouds","Dilution","Thermals","Thunderstorms","Mixing","Rotation","Developing"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2018 Bryan Engelsen"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/101620"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Entrainment, the process by which turbulent clouds introduce dry air from outside the cloud inward via overturning eddies at the cloud edge, can decrease the cloud buoyancy, and the water and/or ice mass it contains, limiting both cloud and precipitation development. Numerous studies have shown that growing cumulus clouds entrain air primarily as a result of the overturning thermal circulation near their tops, but have focused upon cumuli in environments with minimal vertical wind shear. Little attention has been given to investigating the entrainment into developing thunderstorms growing in environments with strong vertical wind shear, or to how rotating updrafts in some thunderstorms (i.e. supercells; produced in environments with specific characteristics of the vertical wind shear) might alter the amount of entrainment they experience. In the current study, idealized, 3D, high-resolution numerical simulations of supercell thunderstorms are used to evaluate entrainment and its effects during the developing and rotating stages of the storms. Entrainment is quantified using an algorithm that first estimates the sub-grid scale edge of the 3D cloud core, defined with specific condensate and vertical velocity thresholds, and then calculates the mass flux into that core. As entrainment proceeds in time, the resulting dilution of the core condensate is tracked. Multiple realizations in the same storm environment are created by altering the storm forcing type (heat flux versus “warm bubble”), the horizontal area over which the forcing is applied, and the vertical wind shear. Results show that vertical wind shear can greatly enhance the entrainment rate into the developing storms, being nearly twice as much locally but even exceeding hundreds of percent more when integrated over the entire storm in time. Similar to past studies, the proportionality of entrainment and dilution in the developing stages of the storms depends upon the local properties of the entrained air and the occurrence of multiple thermals. The method of initiating simulated storms with a “warm bubble” was also found to be detrimental to representing the turbulent eddies required for accurate simulations of entrainment, in the developing stages. Surprisingly, entrainment in the rotating stages of the storms decreased slightly but not substantially, counter to theoretical predictions.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2018-09-27 without embargo terms","The student, Bryan Engelsen, accepted the attached license on 2018-07-18 at 13:10.","The student, Bryan Engelsen, submitted this Thesis for approval on 2018-07-18 at 13:15.","This Thesis was approved for publication on 2018-07-19 at 08:56.","DSpace SAF Submission Ingestion Package generated from Vireo submission #12927 on 2018-09-27 at 10:49:38","Made available in DSpace on 2018-09-27T16:17:59Z (GMT). No. of bitstreams: 2 ENGELSEN-THESIS-2018.pdf: 6462466 bytes, checksum: 1af81acee8fb7d9fc5a0b27d9c19b558 (MD5) LICENSE.txt: 4211 bytes, checksum: f5d479876d4a9ea8c7e78ff0746714ae (MD5) Previous issue date: 2018-07-19"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The effects of entrainment in the developing and rotating stages of supercell thunderstorms"]}]}],"canonical_facts":{"dc:contributor":["Lasher-Trapp, Sonia"],"dc:creator":["Engelsen, Bryan Nicholas"],"dc:date":["2018-09-27T16:17:59Z","2018-07-19","2018-08"],"dc:description":["Entrainment, the process by which turbulent clouds introduce dry air from outside the cloud inward via overturning eddies at the cloud edge, can decrease the cloud buoyancy, and the water and/or ice mass it contains, limiting both cloud and precipitation development. Numerous studies have shown that growing cumulus clouds entrain air primarily as a result of the overturning thermal circulation near their tops, but have focused upon cumuli in environments with minimal vertical wind shear. Little attention has been given to investigating the entrainment into developing thunderstorms growing in environments with strong vertical wind shear, or to how rotating updrafts in some thunderstorms (i.e. supercells; produced in environments with specific characteristics of the vertical wind shear) might alter the amount of entrainment they experience. In the current study, idealized, 3D, high-resolution numerical simulations of supercell thunderstorms are used to evaluate entrainment and its effects during the developing and rotating stages of the storms. Entrainment is quantified using an algorithm that first estimates the sub-grid scale edge of the 3D cloud core, defined with specific condensate and vertical velocity thresholds, and then calculates the mass flux into that core. As entrainment proceeds in time, the resulting dilution of the core condensate is tracked. Multiple realizations in the same storm environment are created by altering the storm forcing type (heat flux versus “warm bubble”), the horizontal area over which the forcing is applied, and the vertical wind shear. Results show that vertical wind shear can greatly enhance the entrainment rate into the developing storms, being nearly twice as much locally but even exceeding hundreds of percent more when integrated over the entire storm in time. Similar to past studies, the proportionality of entrainment and dilution in the developing stages of the storms depends upon the local properties of the entrained air and the occurrence of multiple thermals. The method of initiating simulated storms with a “warm bubble” was also found to be detrimental to representing the turbulent eddies required for accurate simulations of entrainment, in the developing stages. Surprisingly, entrainment in the rotating stages of the storms decreased slightly but not substantially, counter to theoretical predictions.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2018-09-27 without embargo terms","The student, Bryan Engelsen, accepted the attached license on 2018-07-18 at 13:10.","The student, Bryan Engelsen, submitted this Thesis for approval on 2018-07-18 at 13:15.","This Thesis was approved for publication on 2018-07-19 at 08:56.","DSpace SAF Submission Ingestion Package generated from Vireo submission #12927 on 2018-09-27 at 10:49:38","Made available in DSpace on 2018-09-27T16:17:59Z (GMT). No. of bitstreams: 2 ENGELSEN-THESIS-2018.pdf: 6462466 bytes, checksum: 1af81acee8fb7d9fc5a0b27d9c19b558 (MD5) LICENSE.txt: 4211 bytes, checksum: f5d479876d4a9ea8c7e78ff0746714ae (MD5) Previous issue date: 2018-07-19"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/101620"],"dc:language":["en"],"dc:rights":["Copyright 2018 Bryan Engelsen"],"dc:subject":["Entrainment","Supercell","Clouds","Dilution","Thermals","Thunderstorms","Mixing","Rotation","Developing"],"dc:title":["The effects of entrainment in the developing and rotating stages of supercell thunderstorms"],"dc:type":["text"],"thesis:degree_discipline":["Atmospheric Sciences"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:40Z"}