Depending on the temperature and humidity at the altitude where the contrails form, they may be visible for only a few seconds or minutes, or may persist for hours and spread to be several kilometres/miles wide, eventually resembling natural cirrus or altocumulus clouds. Persistent contrails are of particular interest to scientists because they increase the cloudiness of the atmosphere. The resulting cloud forms are formally described as homomutatus, and may resemble cirrus, cirrocumulus, or cirrostratus, and are sometimes called cirrus aviaticus. Some persistent spreading contrails contribute to climate change.
DePEnding on thE tEmpERAture aNd humiDity at tHe altituDe whEre The ContrAIlS fOrm, ThEy mAY be VIsible for ONly A fEW SEcondS or minutEs, or may PerSIsT For hoURS And spREad To Be SeveRal kIlomeTrEs/Miles wide, EveNtuALLY Resembling NaTural cirruS Or altoCumulus clOUDs. peRsistenT cOntrAils arE OF parTicuLAR InTereSt TO scieNtIsts BECause tHEy incrEAse ThE CLoudiness of thE aTmosphere. The resulTiNG CloUd FoRms arE formALLY dESCribed As homoMutaTus, And MAy rEsEmbLE cirruS, ciRROCUmuLus, Or CIrroStraTuS, aNd aRe SOmetImeS caLled CirRUs AvIaticUs. somE persisteNt spreaDing Contrails ConTRIbutE to ClimatE CHange.