PHYSICS SEMINAR SERIES Easter 2015

Understanding the formation of inversions and mixing layers in mountainous terrain remains a challenge to atmospheric science and is limited by basic measurements of ceiling heights, inversion dynamics, and turbulence. Moreover the turbulent dynamics responsible for the mixing of air parcels within the boundary layer in mountainous terrain is also an open question of research, particularly for smoke management and atmospheric deposition applications. The most common tool used for these type of measurements is a single point LiDAR system called a ceilometer. This tools is both expensive and often immobile, primarily deployed at airports for continuous measurements affecting visibility for flight planning. The University of the South in partnership with the US Forest Service Southern Research Station has recently deployed a ceilometer to collect preliminary data on these dynamics on the campus through the senior project of Joel Stewart under the direction of Mr. Kevin Hiers and Dr. Randy Peterson. The initial results are promising and can be easily expanded into active research. We proposed to continuously operate the USFS ceilometer for 2 months to quantify daytime and nighttime mixing heights and compare to predictions from the NWS Fire Weather Forecasts on slopes and at surface of the Cumberland

Thermodynamic Analysis of a

Thermoelectric Device

Mike O’Neil C’15

The University of the South

Wednesday, April 15, 2015 Woods Labs 216

7:00-8:00pm

Mike is a senior physics major from Bethlehem, CT and a pitcher on Sewanee’s NCAA baseball team. Last spring, he presented his work on Alpha Spectroscopy and theory. In that project, he studied the natural radioactive decay of series of elements that exist in our environment as well as in originally purified bottles of chemicals. Using alpha spectroscopy with a silicon surface barrier detector and a multichannel analyzer, he was able to measure the radioactivity from sources such as Thorium, Uranium and other isotopes. After this year, he plans on attending engineering school to acquire a degree in mechanical engineering. For additional information contact: Dr. Randolph S. Peterson rpeterso@sewanee.edu, 931-598-1550

The second law of thermodynamics states that in a closed system, entropy will increase. Using a thermoelectric device as a Seeback-effect heat engine and a Peltier-effect heat pump, the entropy changes for the two engines are measured to isolate the reversible entropy changes from the irreversible changes. The engine efficiencies for a reversible engine as a function of temperature are determined from these measurements and are compared with the second law of thermodynamics. There should be good agreement.