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SUMMARY:Ice nucleation without supercooling: on the search for the most po
 tent ice nucleants. - Professor Valeria Molinero\, University of Utah
DTSTART:20201202T160000Z
DTEND:20201202T170000Z
UID:TALK150241@talks.cam.ac.uk
CONTACT:Lisa Masters
DESCRIPTION:The crystallization of water in clouds plays a key role in wea
 ther and climate through its effect on albedo and precipitation. The unass
 isted\, homogeneous nucleation of ice occurs only at temperatures lower th
 an -32oC\, which are only achieved in high altitude clouds. Ice formation 
 in lower lying\, warmer clouds is promoted by atmospheric aerosols. These 
 aerosols include minerals\, organics\, and biological molecules.  Bacteria
 l proteins are the most potent ice-nucleating agents in the atmosphere and
  the biosphere\, able to nucleate ice at temperatures as high as -1oC. Som
 e organics reach reach comparably high ice nucleation potencies\, and have
  been used for the seeding of clouds to promote precipitation. The molecul
 ar mechanisms by which these potent nucleants interact with ice\, and the 
 mechanisms by which they promote crystallization have long been debated\, 
 but only recently it has been possible to access them through molecular si
 mulations. In this presentation\, I will discuss our work to elucidate the
  mode of binding and nucleation of ice by proteins and organics\, how ice 
 nucleation is modulated by the size and interactions of these particles\, 
 and our quest to find even stronger ice nucleants that can form ice withou
 t supercooling. I will discuss how to achieve the latter through prefreezi
 ng of water above the melting temperature\, and present an integrated view
  of ice premelting\, ice nucleation\, and prefreezing in water. The entici
 ng possibility of accessing the prefreezing regime by small modifications 
 of existing surfaces opens the doors to the design of materials for energy
 -efficient formation of artificial snow and the induction of precipitation
  through cloud glaciation.
LOCATION:Zoom - Meeting ID: 916 8928 5361 Passcode: 848429
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