Sailplane pilot Bruce Miller guides the NSF-owned,
NCAR-operated Schweizer SGS 2-32 aircraft through the
skies in search of storm electricity. (Photo courtesy
MacGillivray Freeman Films and NOVA/WGBH Boston.)
3 November 1995
What is it like to sail on a glider into the heart of a developing thunderstorm? Denver moviegoers can see for themselves beginning on Friday, November 10, when the new film "Stormchasers" debuts at the Phipps IMAX Theater at the Denver Museum of Natural History. This 38- minute film brings the audience a look at tornadoes, hurricanes, and the Indian monsoon, as well as a sailplane used by the National Center for Atmospheric Research (NCAR) to study lightning.
One of the most dramatic segments of "Stormchasers" is its opening, which features a Schweizer SGS 2-32 sailplane heading into a towering cumulus cloud that is soon to become a thunderstorm. The plane, owned by the National Science Foundation (NSF), has been operated by NCAR for more than 25 years. Featured in "Stormchasers" is Boulder pilot Bruce Miller, who has flown the sailplane for NCAR over the past 13 years.
NCAR scientists James Dye and Daniel Breed have used the sailplane since the 1970s. Because the sailplane can ride thermals--ascending parcels of unstable air--it is ideally suited for studying how thermals feed into clouds and developing storms and how the storms' electric fields are generated. Many scientists believe that the electrification process is closely related to a thunderstorm's evolution. When Dye and Breed sent the plane into New Mexico thunderheads in 1984, they found that electric field strengths can triple inside a developing storm in as little time as a minute.
In July and August of this year, Breed oversaw a study using the sailplane in northeast Colorado to study precipitation formation and electrification inside young storms. When ice particles of different sizes develop and begin to collide, they can exchange charges and separate into different regions of a storm. The resulting electrical structure usually features positive charge near the storm top and negative charge at middle to low levels. Data from this summer's flights were combined with output from a radar operated by Colorado State University that distinguishes the sizes and types of precipitation particles in a storm. The results (now being analyzed) should provide insight on how radar data can be used to diagnose the onset of a storm's electrification and lightning.
Along with the sailplane segment, "Stormchasers" includes footage from a tornado research project carried out in Oklahoma during 1994-95. Researchers are shown as they drive near severe thunderstorms, collecting data and watching for tornado development. NCAR scientist Morris Weisman (not in the film) was among the participants in this study, which also included an airborne Doppler radar aboard the NSF's Electra aircraft, also operated by NCAR.
"Stormchasers" will play at the Denver Museum of Natural History through March 28. Tickets are $5 for adults and $4 for children (ages 4-12) and seniors, with discounts for museum members. Details and reservations may be obtained at 322-7009.
"Stormchasers"was produced by MacGillivray Freeman Films for the Museum Film Network and NOVA/WGBH Boston, with major funding provided by NSF. NCAR is managed by the University Corporation for Atmospheric Research under sponsorship by NSF.