1. Development of Ice Nucleation ChamberBy
Gourihar Kulkarni
Supervisor : Dr. Steven Dobbie
Co-Supervisor : Prof. Mike Smith
RSG : Dr. Jim McQuid
With thanks to Prof. John Hallett & Prof. Clive Saunders

2. Outline Introduction Background Current Research Future Plans
1.What is the Motivation for the study
2. Literature , what people have done
4. What r short term and long term plans, how I’m going to achieve.

3. Motivation Ice Formation Radiation Lab studies
Lab studies – although there are number of modelling studies, which provides frame of reference. Expt studies redefines these references and gives more qualitative and quantative insight into microphysical processes.

4. To date Mineral Dust Soot ( burner and fires)- AIDA chamber Coating
Sulphates
Dust
Organics
Both modeling and experimental work has been done.
-Dust has been studies widely. Dust from africa seems to be very popular, as this dust flows over atlantic ocean
To USA and has changed/altered the climate.
Aluminium oxides, iron oxide used as surrogates.
Studied by many scientists.
In few experiments, soot has been artificially manufactured and studied. Plus the comparison has been done
between artificial and real soot.- read AIDA paper
Coating has been studied
Let us enter/study more on experimental sides, what has been done, let us narrow the field.

5. To date cont… Ice Nucleation Growth rates and Habits of ice crystal
Nucleation active surfaces
- There r different types of nucleation modes, which nucleation mode place takes the first place in atmosphere.
These modes I will explain in coming slides, var modes and their significance.
As per the Fukuta 1979, for one particular smoke , condensation-freezing nucleation takes first then contact nucleation- as been observed in no of ice crystal observed vs temp plot.
Importance in cloud parameterisation in global climate models and interpretation of remote sensing msrts.
SS and temp influences the nucleation and growth of ice deposit.
- To begin heterogeneous nucleation, u need something surface, As would expected , different surfaces has different nucleating abilities. Much of ice nucleation research has been dedicated to expts with varieties of materials, and to the search for explanations why each one should be a good or poor nucleator. For given surface there is critical temperature above which ice crystals can appear, taking aerosols. Different surfaces were- crystalline ( natural substances like graphite,cinnabar ) and inorganic crystals ( like AgI, PhI2, CuS) .Also studied on organic crystals like cholesterol,amino acids, aromatic compounds

6. Nucleating Surfaces-Mason 1957 Organic Inorganic
From figure it clealy shows that the orientations of the growing crystals follow, to a large extent , some specific direction with respect to the surface structure. .
Nucleation sites follow patterns set by the surface.

7. Why Experiment Control and steady Environment Ice crystal growth
Introduction from Hallett review
which is usually difficult to obtain in the turbulent atmosphere
We get some idea regarding at what atmospheric variables like temp,RH,SS nucleation takes place.
Which becomes basic ideas to understand atm clouds.
Basically care should be taken that some atmospheric processes are structure insensitive and few are structure
Sensitive.
Ice crystal growth – basic mechanisms which determine the ice surface growth rates are still only very poorly understood. Most confusing aspect of ice crystal growth from the vapor is that the growth rates exhibit a complex dependence on temp. or we can say cloud droplet nucleation and growth rate depend on nucleus mass and gross thermodynamics properties ( vap pr, latent heat ). Also knowledge of ice crystal habit,size, and mass distribution are reqd for accurate cloud parameterization in global climate models and in the interpretation of remote sensing measurements.
Ice memory effect - cycling the growth of a crystal , growing it again, then sublimating it back down, then growing it again - often yielded crystals with non ideal morphologies.

8. Why Experiment cont… Effect of cloud cycling
Importance of In/Organic aerosols
Biogenic origin aerosols
2. Read abbatt paper Which class of aerosol, inorganic or organic, dominates over the other in specific environments? Biomass-burning generated organic aerosols, freshly emitted particles of biogenic origin & high degree of photochemical processing
- Cloud nucleating roles
4. All these uncertainities are solved using lab studies

9. Nucleation Mechanisms

10. Definitions Supersaturation (SS) SS in % = {(P / Pe) – 1 } * 100
IN, CCN, Organics,Inorganics,minerals
Thermal Diffusion Chamber
Types of aerosols
Before going into detail, let me explain few terms widely used in chamber – cloud chamber study.
Minerals are naturally occurring inorganic compounds that have inorganic origins. The chemical composition of a mineral can be expressed by a chemical formula, and a mineral has unique physical and chemical properties.
4. Types hygroscopic and hydrophobic

11. How chamber works Warm T SS Cold

12. Past Experiments
Wilson Cloud Chamber

13. Laboratory Cloud Chamber
Laboratory cold chamber, Desert Research Institute, University of Nevada, Reno, Nevada, USA

14. Static Diffusion Chamber
Static-expansion thermal diffusion chamber

15. Shortcomings Aerosol samples Static/Continuous flow diffusion chamber
In/Organic coating of aerosols
Pressure (in)dependence
Laser interferometry
Re/Pre- activation
Various aerosol samples are not tested. We r collecting samples through out the world.
Doug Parker has brought some samples from his recent field trip. Samples with var altitudes will be tested.
West Africa – aerosols varying with altitudes
Contact has been made with Chemistry dept, to see any instrument which can do coating over dust or mineral
Dust or any any aerosols, using organic or vocs or OH
This is used to measure changes in the crystal thickness as it grows, which is not done in any cloud chamber or nucleation chamber
Considering all these disadvantages of previous chambers, we have designed unique chamber, yet still modification will be done. It is always iterative procedure.

16. Our Chamber Ours is different than others, How,
Able to use any surfaces – organic, inorganic, natural
Any aerosol samples can be located
Can act as static diffusion chamber and flow diffusion chamber
Adv and disadv of these chambres. Adv of static- samples can be gathered and processed later without degradation of the nuclei
Pressure dependence/independence

17. Specifications Material Properties - Glass , Perspex Saphire Brass
Stainless Steel
Microscope -
Working distance, size of aerosol and pixel,
cost

18. Some Mathematics LAPLACE Equation Finite Difference Temperature
Profiles

19. Temperature Profiles

20. Aerosol Time Of Flight Mass Spectrometer (ATOMFS)
Aotmfas used for-
Size and chemical composition of individual aerosol particle.
Specific compounds that makes the aerosol particles,

21. Future Plan Future Short Term Blue Print Modeling ( FLUENT ) Samples
Expertise- dust generator, ATOMFS,ER
Future Long Term
Validation/calibration
Pressure
Coatings