1. Institute of Atmospheric Sciences South Dakota School of Mines and Technology A Cloud Physics Facility for DUSEL John Helsdon South Dakota School of Mines & Technology & Patrick Chuang Univ. of California – Santa Cruz

2. Institute of Atmospheric Sciences South Dakota School of Mines and Technology Big Question 2001 National Research Council Report  Examined Key Questions in Climate Science  60% of Climate Sensitivity Due to Feedbacks Involving: Water vapor CLOUDS Conclusion:  Climate Uncertainty Will Remain Until a More Fundamental Understanding of Clouds is Achieved

3. Institute of Atmospheric Sciences South Dakota School of Mines and Technology Clouds and Climate Key Component of Climate System. Clouds Affect:  Incoming Sunlight  Outgoing Longwave IR  Vertical Transport of Energy, Moisture, Trace Gases  Precipitation in All Forms (Including Cleansing)  Atmospheric Chemistry SO 2 oxidation to SO 4 in cloud droplets Nitrogen fixation by lightning

4. Institute of Atmospheric Sciences South Dakota School of Mines and Technology Environments for Studying Clouds  Laboratory Studies Well-controlled Unrealistic length scales and residence times  Field Studies Realistic conditions Poorly-controlled Difficult sampling conditions (aircraft) Expensive  Model Studies Well-controlled, detailed results Need to be tested and validated against observations  Vertical Shaft Studies Reasonably well-controlled Reasonably realistic length scales and residence times Easier sampling conditions Particles at terminal velocity

6. Institute of Atmospheric Sciences South Dakota School of Mines and Technology Precipitation Formation  How Does Precipitation Form in Clouds? Initiation of precipitation in warm clouds is a longstanding problem in cloud physics Ice phase interactions are primary path to precipitation, but poorly understood Vertical shaft cloud would permit testing of central hypotheses, such as the role of aerosol distributions, turbulence, electrical effects, temperature, etc.

7. Institute of Atmospheric Sciences South Dakota School of Mines and Technology Aerosol-Cloud Interactions  What are Properties of Clouds Formed From Aerosols Composed of Mixture of Organic and Inorganic Compounds? Activation behavior of organic aerosols poorly understood Vertical shaft cloud permits controlled experiments with complex aerosol (e.g., biomass burning, combustion aerosol) in realistic cloud conditions

8. Institute of Atmospheric Sciences South Dakota School of Mines and Technology Cloud Electrification Studies  Ice Particle Interactions in Supercooled Cloud Environment Thought to Cause Charge Separation up to Lightning Many types of ice particles in natural cloud Interaction coefficients poorly defined Vertical shaft cloud with mixed-phase water environment and detailed observations will help resolve interaction matrix

9. Institute of Atmospheric Sciences South Dakota School of Mines and Technology Cloud-Turbulence Interactions  How Does Turbulence Affect the Evolution of Cloud Properties? Microscale turbulence (~ mm to cm length scales) hypothesized to affect cloud processes such as condensation, collision-coalescence/aggregation, radiative transfer, but experimental data lacking Vertical shaft cloud exhibits higher Reynolds numbers than achieved in laboratory conditions, permitting better experimental data to address questions

10. Institute of Atmospheric Sciences South Dakota School of Mines and Technology Cloud Chemistry  How do Models of Aqueous Phase Chemistry in Clouds Compare with Measurements? Conversion of S(IV) to S(VI) well known to be important for atmospheric chemistry Reactions involving other species also believed to be significant Vertical shaft cloud would provide real cloud conditions on timescales sufficiently long to study such reactions

11. Institute of Atmospheric Sciences South Dakota School of Mines and Technology Other Studies  Cloud Remote Sensing  Cloud Radiative Transfer  Instrument Inter-comparison  Adiabatic Parcel Models  Multi-Dimensional Simulation Models

12. Institute of Atmospheric Sciences South Dakota School of Mines and Technology It is Fitting that a Cloud Physics Facility Should be Associated with a Particle Physics Facility. One of the Original Particle Physics Detectors was the Wilson Cloud Chamber.