Ice Nucleation

As an interdisciplinary group, we welcome applications from those with a background in a range of disciplines (for example, Environmental Science, Chemistry, Physics, Engineering, Maths) for MSc, PhD and postdoctoral positions as well as undergraduate and summer research projects. Funding for PhD projects can be obtained through the Doctoral Training Programme (DTP), independently funded projects as well as university or other funding sources.

Our goal is to improve understanding of the fundamental role aerosols and clouds play in the Earth’s climate system. We research the properties of aerosol particles in the Earth’s atmosphere and how these particles influence clouds through laboratory, field and numerical modelling projects. We also use this knowledge to develop industrial applications for controlling freezing such as cryopreservation.

Current opportunities

Visit phd.leeds.ac.uk to search our funded projects and opportunities.

Potential PhD or Masters projects

This list is not meant to be definitive; the group is always open to new ideas.

• Mineral dust particles as the seeds of ice in clouds. Ice formation in clouds remains one of the least well understood cloud processes. In this laboratory project you will quantify the role that mineral dusts play in the formation of ice in clouds. This novel and exciting project is on the interface between atmospheric science and geochemistry. We recently discovered that feldspars are the most efficient mineral in desert dust ice nucleate (Atkinson et al., Nature, 2013). But, there are many types of feldspar and it is unclear which are effective ice nuclei and which are not. Read more here. 
   
• The mystery of triangular ice crystals in the atmosphere. We are all familiar with the six-fold rotational symmetry of snow and ice crystals and it is well established that this stems from the hexagonal crystal structure of ice.  However, atmospheric ice crystals with only three-fold rotational symmetry are frequently observed, which is inconsistent with the hexagonal space group symmetry of ordinary ice. We think that this is related to disorder in the crystal structure which we have observed when water droplets freeze (Malkin et al. PNAS, 2012). Given ice crystal shape is critically important for cloud radiative properties and also the rate at which crystals fall this is extremely important to understand.  You will grow ice crystals under well-defined conditions in a microscope cold stage and also in an X-ray diffractometer.  This will allow you to work out the relationship between ice crystal shape and crystal structure. Read more here. 
   
• Quantifying ice nuclei concentrations in nature. Ice nuclei nuclei concentrations are extremely poorly quantified in the Earth’s atmosphere and surprisingly few measurement have been made. We have developed new techniques for quantifying the concentration of ice nuclei in the atmosphere using technologically simple techniques. We recently used these techniques on a UK research aircraft in the Arctic and would like to deploy these techniques elsewhere. You will further develop this technique and quantify ice nuclei concentrations in the atmosphere. 
   
• Heterogeneous chemistry of glassy and ultra-viscous droplets. It was recently discovered that aerosol particles can exist in a glassy solid state, rather than a liquid one in the Earth’s atmosphere, but it is unclear how these particles interact with trace gasses. You will use newly developed techniques using a Raman microscope to investigate the rate of chemical reactions within ultra-viscous, highly metastable, solution droplets. We have worked on ice nucleation by glassy aerosol particles (Murray et al., Nature Geoscience, 2010) and quantified diffusion coefficients (Price et al., ACP 2013) 
   
• Chemical processing of ice nuclei in the atmosphere. Mineral dust is one of the most important ice nuclei globally, however first order questions remain unanswered. Our discovery that feldspar is the material in mineral dust which makes it an effective IN suggests that mineral dust will be particularly sensitive to atmospheric acids. This sensitivity arises because feldspars react with acids to form clay minerals and this is consistent with the deactivation or passivation of mineral dust IN by acid in previous experiments. The rate at which acid passivation happens in the atmosphere and the quantitative impact on IN concentrations is unknown. Our exploratory global model studies show acid passivation is very likely an important process in determining atmospheric IN concentrations, especially in regions remote from sources; but it remains to be quantified. In this project you will quantify the rate of acid deactivation of ice nuclei. 
   
• Nucleation of ice by biological material. Certain types of bacteria and fungus are some of best ice nuclei we know of, but their impact on clouds remains poorly quantified. Ice nucleation and crystallisation in cells is also important for cryo-preservation, but is again poorly understood. We recently worked on ice nucleation by biological material in soils (O’Sullivan et al., ACP, 2014) You will use our droplet freezing instrumentation to quantify how effectively various biological ice nuclei nucleate ice.

Postdoctoral fellowship opportunities

Our school has a strong record of supporting aspiring scientists in building an independent career through postdoctoral fellowship schemes. Funding is available from the Royal Society, NERC, EPSRC and the Marie Curie Fellowship. If you are interested in working alongside our team as a fellow, please contact Professor Murray.

Masters course

We offer an MRes in Climate and Atmospheric Science. This is a one-year course designed to prepare graduates in the Physical Sciences and Maths for research careers in Climate, Atmospheric or Environmental Sciences.

Undergraduate summer students

We welcome suitably qualified applicants for summer scholarship programmes. It is advisable to contact Professor Murray in January in order to meet application deadlines.

Please see below for some ideas on possible topics.

• The effects of atmospheric aging (acidity) on the ice nucleating effectiveness of volcanic ash. Volcanic ash is periodically injected into the atmosphere, but our understanding of its impact on ice formation in clouds is poor. In this project you will would with a volcanic ash expert in the Ice Nucleation group to experimentally quantify the role of acids in altering the ice nucleating properties of volcanic ash. You should have a desire to work in a laboratory environment. High quality work may lead to co-authoring a future publication. 
   
• Quantifying the concentration of ice nucleating particles in rain water. Ice nucleating aerosol particles in the Earth’s atmosphere dramatically alter cloud properties and trigger rainfall, however their abundance at cloud altitudes is very poorly defined.  In this project you will collect rain water samples over the course of your project and determine the concentration of ice nucleating particles in the rain water and use this information to derive the atmospheric ice nucleating particle concentration at cloud altitudes. You should have a desire to work in a laboratory environment and also collect rain samples from a suitable field site. High quality work may lead to co-authoring a future publication. 
   
• The fundamentals of ice nucleation. The nucleation of ice in clouds is of fundamental importance for climate and precipitation, and therefore life on earth, but is extremely poorly understood. We are working towards a better quantitative understanding of why certain materials are better at nucleating ice and why our instruments sometime produce conflicting results, you will contribute to this effort. You should have a desire to work in a laboratory environment. High quality work may lead to co-authoring a future publication.