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Heterogeneous nucleation of ice particles on glassy aerosols under cirrus conditions


Ice clouds in the tropical tropopause layer play a key role in dehydrating air as it enters the stratosphere1,2. However, in situ measurements show that water vapour within these clouds is unexpectedly supersaturated3,4,5; normally the growth of ice crystals rapidly quenches supersaturation3. The high in-cloud humidity may be related to the low number of ice crystals found in these clouds4,6, but low ice number densities are inconsistent with standard models of cirrus cloud formation involving homogeneous freezing of liquid aerosols7. Aqueous aerosols rich in organic matter are ubiquitous in the atmosphere8,9, and under cirrus conditions they are known to become glassy10,11, that is, amorphous, non-crystalline solids. Here we report experiments in a cloud simulation chamber that demonstrate heterogeneous nucleation of ice on glassy solution droplets. Cirrus residues measured in situ showed ice nuclei rich in oxidized organic matter12, consistent with heterogeneous nucleation on glassy aerosols. In addition, using a one-dimensional cirrus model, we show that nucleation on glassy aerosols may explain low ice crystal numbers and high in-cloud humidity in the tropical tropopause layer. We propose that heterogeneous nucleation on glassy aerosols is an important mechanism for ice nucleation in the tropical tropopause layer.

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Figure 1: Ice particle concentrations for expansion chamber experiments.
Figure 2: The onset of ice formation and fraction of citric acid aerosol particles that nucleated ice in a number of expansion experiments.
Figure 3: Time series of model results averaged between 17.25 and 17.35 km.
Figure 4: Model result for Nice and RHi allowing heterogeneous nucleation on glassy particles, for a range of cooling rates.


  1. Holton, J. R. & Gettleman, A. Horizontal transport and the dehydration of the stratosphere. Geophys. Res. Lett. 28, 2799–2802 (2001).

    Article  Google Scholar 

  2. Jensen, E. J., Toon, O. B., Pfister, L. & Selkirk, H. B. Dehydration of the upper troposphere and lower stratosphere by subvisible cirrus clouds near the tropical tropopause. Geophys. Res. Lett. 23, 825–828 (1996).

    Article  Google Scholar 

  3. Peter, T. et al. When dry air is too humid. Science 314, 1399–1402 (2006).

    Article  Google Scholar 

  4. Krämer, M. et al. Ice supersaturations and cirrus cloud crystal numbers. Atmos. Chem. Phys. 9, 3505–3522 (2009).

    Article  Google Scholar 

  5. Shilling, J. E. et al. Measurements of the vapour pressure of cubic ice and their implications for atmospheric ice clouds. Geophys. Res. Lett. 33, L17801 (2006).

    Article  Google Scholar 

  6. Jensen, E. J. et al. Formation of large (similar or equal to 100 μm) ice crystals near the tropical tropopause. Atmos. Chem. Phys. 8, 1621–1633 (2008).

    Article  Google Scholar 

  7. Jensen, E. J., Pfister, L., Bui, T.-P., Lawson, P. & Baumgardner, D. Ice nucleation and cloud microphysical properties in tropical tropopause layer cirrus. Atmos. Chem. Phys. 10, 1369–1384 (2010).

    Article  Google Scholar 

  8. Froyd, K. D. et al. Aerosol composition of the tropical upper troposphere. Atmos. Chem. Phys. 9, 4363–4385 (2009).

    Article  Google Scholar 

  9. Murphy, D. M. et al. Single-particle mass spectrometry of tropospheric aerosol particles. J. Geophys. Res. Atmos. 111, D23S32 (2006).

    Google Scholar 

  10. Murray, B. J. Inhibition of ice crystallisation in highly viscous aqueous organic acid droplets. Atmos. Chem. Phys. 8, 5423–5433 (2008).

    Article  Google Scholar 

  11. Zobrist, B., Marcolli, C., Pedernera, D. A. & Koop, T. Do atmospheric aerosols form glasses? Atmos. Chem. Phys. 8, 5221–5244 (2008).

    Article  Google Scholar 

  12. Froyd, K. D., Murphy, D. M., Lawson, P., Baumgardner, D. & Herman, R. L. Aerosols that form subvisible cirrus at the tropical tropopause. Atmos. Chem. Phys. 10, 209–218 (2010).

    Article  Google Scholar 

  13. Koop, T., Luo, B. P., Tsias, A. & Peter, T. Water activity as the determinant for homogeneous ice nucleation in aqueous solutions. Nature 406, 611–614 (2000).

    Article  Google Scholar 

  14. Möhler, O. et al. Experimental investigation of homogeneous freezing of sulphuric acid particles in the aerosol chamber AIDA. Atmos. Chem. Phys. 3, 211–223 (2003).

    Article  Google Scholar 

  15. Möhler, O. et al. The effect of organic coating on the heterogeneous ice nucleation efficiency of mineral dust aerosols. Environ. Res. Lett. 3, 025007 (2008).

    Article  Google Scholar 

  16. Koop, T. Homogeneous ice nucleation in water and aqueous solutions. Z. Phys. Chem. 218, 1231–1258 (2004).

    Article  Google Scholar 

  17. Cziczo, D. J. et al. Observations of organic species and atmospheric ice formation. Geophys. Res. Lett. 31, L12116 (2004).

    Article  Google Scholar 

  18. Kärcher, B. & Spichtinger, P. in Clouds in the Perturbed Climate System, Their Relationship to Energy Balance, Atmospheric Dynamics, and Precipitation (eds Heintzenberg, J. & Charlson, R. J.) (MIT Press, 2009).

    Google Scholar 

  19. Kärcher, B. Supersaturation, dehydration, and denitrification in Arctic cirrus. Atmos. Chem. Phys. 5, 1757–1772 (2005).

    Article  Google Scholar 

  20. Jensen, E. J. et al. Ice supersaturations exceeding 100% at the cold tropical tropopause: Implications for cirrus formation and dehydration. Atmos. Chem. Phys. 5, 851–862 (2005).

    Article  Google Scholar 

  21. Lawson, R. P. et al. Aircraft measurements of microphysical properties of subvisible cirrus in the tropical tropopause layer. Atmos. Chem. Phys. 8, 1609–1620 (2008).

    Article  Google Scholar 

  22. Gensch, I. V. et al. Supersaturations, microphysics and nitric acid partitioning in a cold cirrus cloud observed during CR-AVE 2006: An observation-modelling intercomparison study. Environ. Res. Lett. 3, 035003 (2008).

    Article  Google Scholar 

  23. Khvorostyanov, V. I., Morrison, H., Curry, J. A., Baumgardner, D. G. & Lawson, P. High supersaturation and modes of ice nucleation in thin tropopause cirrus: Simulation of the 13 July 2002 cirrus regional study of tropical anvils and cirrus layers case. J. Geophys. Res. 111, D02201 (2006).

    Google Scholar 

  24. Spichtinger, P. & Gierens, K. M. Modelling of cirrus clouds—Part 2: Competition of different nucleation mechanisms. Atmos. Chem. Phys. 9, 2319–2334 (2009).

    Article  Google Scholar 

  25. Eastwood, M. L. et al. The effects of sulfuric acid and ammonium sulphate coatings on the ice nucleation properties of kaolinite particles. Geophys. Res. Lett. 36, L02811 (2009).

    Article  Google Scholar 

  26. Murray, B. J., Knopf, D. A. & Bertram, A. K. The formation of cubic ice under conditions relevant to Earth’s atmosphere. Nature 434, 202–205 (2005).

    Article  Google Scholar 

  27. Murray, B. J. Enhanced formation of cubic ice in aqueous organic acid droplets. Environ. Res. Lett. 3, 025008 (2008).

    Article  Google Scholar 

  28. Murray, B. J. & Bertram, A. K. Inhibition of solute crystallisation in aqueous H+–NH4+–SO42−–H2O droplets. Phys. Chem. Chem. Phys. 10, 3287–3301 (2008).

    Article  Google Scholar 

  29. Peter, T. et al. Ultrathin tropical tropopause clouds (UTTCs): I. Cloud morphology and occurrence. Atmos. Chem. Phys. 3, 1083–1091 (2003).

    Article  Google Scholar 

  30. Murphy, D. M. & Koop, T. Review of the vapour pressures of ice and supercooled water for atmospheric applications. Q. J. R. Meteorol. Soc. 131, 1539–1565 (2005).

    Article  Google Scholar 

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B.J.M. thanks the Natural Environment Research Council (NE/D009308/1) and the European Research Council (FP7, 240449—ICE) for fellowships. We acknowledge the FP6 European Network of Excellence Atmospheric Composition Change ‘ACCENT’ for travel funds (GOCE CT-2004—505337). T.W.W. thanks the Charles Brotherton Trust for a Studentship and the Aerosol Society for further financial support. We thank the AIDA operators and technicians for their support during the experiments. The water vapour measurements were partially funded by the Helmholtz Virtual Institute Aerosol Cloud Interaction (VIACI). We thank T. Leisner for helpful discussions and M. Pilling for commenting on this manuscript.

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B.J.M. oversaw this project, sought financial support for it and wrote this manuscript. S.D. led the modelling aspects in collaboration with S.M.R.K.A. and B.K. T.W.W. analysed the data provided by the AIDA team. O.M. led the AIDA team, which included M.S., R.W., S.B., M.N. and H.S., who operated the AIDA chamber and equipment. B.J.M., T.W.W. and Z.C. helped with the AIDA experiments. V.E. and S.W. provided the analysed AIDA water vapour data.

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Correspondence to Benjamin J. Murray.

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Murray, B., Wilson, T., Dobbie, S. et al. Heterogeneous nucleation of ice particles on glassy aerosols under cirrus conditions. Nature Geosci 3, 233–237 (2010).

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