Making it rain: Designing a convection-cloud chamber for exploring interactions between aerosols, clouds and precipitation
Raymond A. Shaw
Michigan Tech University
Friday, February 28, 12:00 PM, C215 ESC
Abstract:
The 2021 Nobel Prize in Physics recognized the development of computational models for the energy budget controlling Earth’s climate, which involves absorption and emission of electromagnetic radiation, and thermal plus phase-change-related energy transport through atmospheric convection. All of these processes are influenced by clouds, and a central challenge of climate science is to seek simple but physically-based representations of cloud and precipitation formation that can be incorporated into coarse-resolution computational models. Clouds are collections of droplets and ice crystals, formed on aerosol particles, all interacting within a turbulent environment. Understanding these interactions is central to current challenges ranging from the influence of clouds on climate, to solar radiation management strategies like marine cloud brightening. Turning to the laboratory is one way to make progress because we control or characterize all initial and boundary conditions. In the “Pi convection-cloud chamber”, a pi-cubic-meter turbulent cloud is generated by feeding aerosols into a water-supersaturated environment created by moist Rayleigh-Benard convection. The resulting cloud microphysical and optical properties are similar to those observed in shallow reflective clouds that strongly modulate Earth’s climate. Over the last decade the Pi chamber has provided insight into cloud processes related to the “birth” of clouds through aerosol activation and the “death” of clouds through turbulent mixing with dry air. Now, the ACDC2 consortium has been developing a design for a much larger convection-cloud chamber that will allow us to explore the most crucial and uncertain stage of cloud evolution: the formation of precipitation. It would be the only research facility in the world with this capability, and it’s a dream that bright, young physicists can help create.
Biographical Sketch:
Dr. Shaw's research involves the physics of the earth's atmosphere, with an emphasis on clouds and experimental tools for studying clouds. Clouds are transient collections of particles that interact strongly with visible radiation: they are transient in the sense that the particles in a cloud are continuously evolving in size and thermodynamic phase (liquid versus ice), and the cloud itself dissipating if the particles are not continuously "fed" through atmospheric motions or radiative cooling. Research in Shaw's group has focused on understanding the influence of turbulence on cloud particle growth through condensation and collisions, and on understanding the nucleation process through which ice forms from liquid water. Shaw's group is actively involved in the development of methods for studying clouds in controlled conditions in the laboratory as well as in the atmosphere itself. For example, digital holography is applied to particle tracking in turbulent laboratory clouds, and to measurement of particle size distributions in clouds sampled by research aircraft.
Alumni Event
Alumni Event
Friday, March 7, 12:00 PM, C215 ESC
Abstract:
Biographical Sketch:
Science & Nuclear Weapons Proliferation
James Wells
University of Michigan
Friday, March 14, 12:00 PM, C215 ESC
Abstract:
Fear of nuclear weapons use and the proliferation of nuclear weapons throughout the world is rising fast. Russia is threatening its use. China is building at break-neck pace. Ukraine regrets giving up their weapons. These factors and more have led multiple countries to express strong interest in obtaining nuclear weapons. This talk will discuss the steps and challenges of building usable nuclear weapons, and what the USA and others can do to stop the dangerous pursuit. We will illustrate the progress and responses, such as missile defense, with a discussion of the successful nuclear weapons program of North Korea. Our primary emphasis will be on the scientific and technological breakthroughs needed. Important policy/diplomatic issues will also be highlighted, which are integral to the story.
Biographical Sketch:
Professor Wells' research focuses on high energy particle science. For ten years he worked with security officials from the American Physical Society and the Center for Global Security Research at Livermore.
Jacob Barker
University of Arizona
Thursday, March 27, 4:00 PM, C247
Abstract:
Biographical Sketch:
Cryo-EM
Gunnar Schroeder
Heinrich-Heine University Düsseldorf
Friday, March 28, 12:00 PM, C215 ESC
Abstract:
Professor Schroeder works on both the application of cryo-EM for biomolecular structure determination and also the development of computational tools for cryo-EM. His focus is to determine of structures of amyloid fibrils in collaboration with colleagues at the ICS-6 in Jülich and the IPB in Düsseldorf. Amyloid fibrils play a significant role in many neurodegenerative diseases, such as Alzheimers or Parkinsons disease.
Biographical Sketch:
Nuclear Engineering
Taylor Kimball
University of Utah
Friday, April 4, 12:00 PM, C215 ESC
Abstract:
Kimball’s innovative work introduces a new method to create calibration standards for use in radiation detectors at radioxenon measurement labs, which support the Comprehensive Test Ban Treaty (CTBT). His research supports the CTBT by providing better tools for detecting nuclear explosions, ensuring more accurate monitoring and compliance with the treaty.
Biographical Sketch:
Deep (machine) learning
Pratik Chaudhari
University of Pennsylvania
Friday, April 11, 12:00 PM, C215 ESC
Abstract:
Biographical Sketch:
Dr.Chaudhari is an Assistant Professor in the Electrical and Systems Engineering department and a core faculty in the General Robotics, Automation, Sensing and Perception (GRASP) Laboratory. He holds a secondary appointment in the Computer and Information Sciences department and is a member of the Applied Mathematics (AMCS) graduate group, Penn Institute for Computational Science (PICS), Center for AI-enabled Systems: Safe, Explainable, and Trustworthy (ASSET) and Center For AI And Data Science For Integrated Diagnostics (AI2D).
Previously, he held a joint position as a Senior Applied Scientist at Amazon Web Services and was a post-doctoral researcher at the California Institute of Technology in Computing and Mathematical Sciences.
He defended his PhD thesis in the Computer Science department at University of California, Los Angeles in 2018 where he worked with Stefano Soatto in the UCLA Vision Lab. He has Engineer's (2014) and Master's (2012) degrees in Aeronautics & Astronautics from the Massachusetts Institute of Technology where he worked with Emilio Frazzoli at the Laboratory of Information and Decision Systems (LIDS). He was in the Aerospace Engineering department at IIT Bombay for his undergraduate studies until 2010.
He has worked extensively on self-driving cars in the areas of motion planning and computer vision at nuTonomy Inc (now Hyundai-Aptiv Motional).
We welcome anyone who wish to attend, and typically serve refreshments ten minutes before the colloquium begins. Speakers generally keep their presentation accessible to undergraduate physics students.