Seminars

A seminar or talk, either on campus or off campus

Seminar: Retrieving the cumulus entrainment rate remotely

Dr. Timothy Wager, Creighton University Department of Physics

Cumulus clouds are an important, yet underobserved, part of the climate system.  As cumuli develop, they mix with the surrounding environment through the process of entrainment, which impacts the lifespan, droplet size, and depth of the clouds. In order to properly simulate the atmosphere for climate and weather forecasting, these impacts must be accounted for but the small spatial extent of these clouds means the entrainment process must be must be parameterized, a difficult problem due in part to the lack of available observations of entrainment.  Entrainment has been traditionally measured via direct penetration of clouds by instrumented aircraft but the expense and difficulty associated with this method means that the scope of the available entrainment observations is small.

To expand the number of observations of entrainment available for analysis, a remote retrieval method using ground-based instrumentation has been developed.  This method, called the Entrainment Rate In Cumulus Algorithm (ERICA) retrieves the fractional entrainment rate through a Gauss-Newton optimal estimation retrieval.  High temporal resolution observations of cumuli and their environment and a guess of the entrainment rate are ingested by a cloud parcel model, in this case the Explicit Mixing Parcel Model (EMPM).  The entrainment rate is iteratively adjusted until the modeled cloud matches the observations.  ERICA has been shown to correspond well with other methods of retrieving the entrainment rate.  Results for both shallow continental cumulus and deep tropical convection will be shown.

Location
Hixson-Lied Science Building G69
Date of Event

Seminar: Why Isn't God Ambidextrous

Why Isn't God Ambidextrous?

Dr. Tim Gay, Department of Physics, University of Nebraska – Lincoln

Thursday, January 29nd, 2015: 4:00 p.m., Hixon-Lied Science Building, 244

Until 1957, scientists thought that the fundamental laws of Nature must be the same whether they were applied to our Universe or the Universe that is a mirror reflection of our own.  The implications of the discovery that this is not true - essentially that Nature is "handed" - will be discussed.  Some interesting applications of handedness, or "chirality"  in agriculture, biology, chemistry, and physics will be presented.  I will also talk about some new physics experiments on chirality that may shed light on how life began on this planet.

Dr. Gay’s group is interested in polarized electron physics. Their work involves studies of polarized electrons scattering from atomic and chiral molecular targets, the development of novel sources of polarized electrons and electron polarimeters, and investigations of the fundamental nature of the electron.

Location
HLSB 244
Date of Event

Seminar: Shedding Light on Dark Matter using Cryogenic Detectors

Evidence from multiple indirect measurements implies that 80% of the mass in the universe is dark, non-baryonic and hence is composed of a new type of undiscovered particles.  I will describe why Weakly Interacting Massive Particles (WIMPs) are the most popular candidate for the dark matter and describe how WIMPs would interact in a detector.  I will then describe a leading experiment attempting to directly detect WIMP interactions, the Super Cryogenic Dark Matter Search (SuperCDMS) and present results.

Dr. Sander is interested in finding evidence of new physics. Towards that end, he is a primary investigator on the SuperCDMS collaboration looking to directly detect dark matter. He is also working on developing new detection techniques for the next generation of rare event searches.

Location
Hixson-Lied G59
Date of Event
Contact info
AndrewBaruth@creighton.edu

Physics Antique Roadshow

 Tom Greenslade, Ph.D., one of the foremost experts on antique physics apparatus will present "The Creighton Physics Antique Road Show," during Creighton University's Department of Physics colloquium. Some of Creighton's antique apparatus, which includes items from the 1898 Trans-Mississippi Exposition that was held in Omaha, will be on display in a nearby room.

Location
HL G59
Date of Event
Contact info
Jack Gabel (jackgabel@creighton.edu)

Theme by Danetsoft and Danang Probo Sayekti inspired by Maksimer