Atmospheric Chemistry of Contrails Vignesh Unnithan GTID 903572553

What are contrails? • (Con)densation trails from the exhaust of aircrafts • Suspended water

How do contrails form? • Combustion of jet fuel gives a lot of water,

Persistence of Contrails • Low humidity, the contrail will be short-lived Ice crystals evaporate

Other types of Contrails • Military craft contrails: • Black soot • Poor fuel

Other types of Contrails • Chaffs • Anti radar measure • Chaff fibers form

Chemtrail claims and arguments Claim: Long-lasting contrails are something new and must have harmful

Chemtrail claims and arguments “Normal” contrail Claim: Contrails should be purely white if they

Chemtrail claims and arguments Claim: Contrails should be purely white if they are only

Chemtrail claims and arguments Claim: Grid patterns of contrails in the sky are evidence

References • "Contrails Facts" (PDF). US Air Force. 13 October 2005. Archived from the

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Atmospheric Chemistry of Contrails Vignesh Unnithan (GTID: 903572553)

What are contrails? • (Con)densation trails from the exhaust of aircrafts • Suspended water droplets and ice crystals forming clouds • Persistence depends on ambient atmospheric conditions

How do contrails form? • Combustion of jet fuel gives a lot of water, among other products. • Low temperature and high humidity at cruising altitudes (35000 ft). • Exhaust mixes with local air, condensing and crystallizing.

Persistence of Contrails • Low humidity, the contrail will be short-lived Ice crystals evaporate short trails follow • High humidity, the contrail will persist ice particles grow trail extends by miles spread by turbulence, solar heating

Other types of Contrails • Military craft contrails: • Black soot • Poor fuel & engine efficiency • Only during take-off • Space craft contrails: • Combustion of solid fuel • Smoke and contrail mix

Other types of Contrails • Chaffs • Anti radar measure • Chaff fibers form radar-reflective cloud • 500 tons released per year • Chaff fibers • 60% glass fiber and 40% aluminum by weight • 25 microns in diameter and 1 to 2 cm • 10 -100 times larger than PM 10 and PM 2. 5

Chemtrail conspiracies – Hoax or Truth?

Chemtrail claims and arguments Claim: Long-lasting contrails are something new and must have harmful chemicals “Normal” contrail Long-lasting chemtrail

Chemtrail claims and arguments “Normal” contrail Claim: Contrails should be purely white if they are only comprised of water

Chemtrail claims and arguments Claim: Contrails should be purely white if they are only comprised of water Red and Iridescent ‘chemtrails’

Chemtrail claims and arguments Claim: Grid patterns of contrails in the sky are evidence of a systematic spraying operation ‘Chemtrail’ grid

Thank You

References • "Contrails Facts" (PDF). US Air Force. 13 October 2005. Archived from the original (PDF) on 6 March 2013. • https: //www. bbc. com/news/blogs-trending-42195511 • Appleman, H. , 1953. The formation of exhaust condensation trails by jet aircraft. Bulletin of the American Meteorological Society 34: 14 -20. Brewer, A. W. , 1946. Condensation trails. Weather 1: 34 -40.