Douglas N. Yarger

A forecasting activity for a large introductory meteorology course

A large lecture introductory course at Iowa State University has used a forecasting activity since 1993 to actively engage students in doing science. This automatically scored Web-based activity requires students to evaluate selected weather parameters and to also select appropriate physical reasons for their values. Participants can select from more than 1000 cities in the United States for their forecast city. This activity engages students in doing what practicing meteorologists do. Further, forecast scores demonstrate increased understanding throughout the course. Design considerations were based on constructivist learning theory in order to address goals articulated by national panels; to promote problem solving, collaboration, and communication skills by being involved in scientific inquiry.

Relationship of atmospheric ozone profiles to solar magnetic activity

The observed relationship between atmospheric vorticity variations and solar magnetic sector boundary passages is examined for a possible connection via ionization changes affecting ozone distributions. A superposed epoch analysis was performed on Umkehr distributions for 18 years from Arosa, Switzerland, with use of more than 500 solar sector boundary passages as keyday zero. No significant responses are observed in any Umkehr level or in total observed ozone amounts. Further analyses on shorter records for Belsk, Poland, and Hohenpeissenberg, West Germany, corroborate these results. Another analysis for Arosa with about 100 type IV solar flares as keyday zero also shows no definitive trend. It is concluded that ozone distribution changes cannot be the primary causative mechanism for vorticity variations.

An example of a virtual reality learning environment

Using photographic, computer graphical and experimental data, a pilot model of a tornadic supercell thunderstorm was created in a virtual environment at Iowa State University. One goal of the project was to give students the virtual experience of being in the field, experiencing the dramatic features of typical tornadic supercells, and stimulating them to explore and ask questions in this learning environment. Initial feedback from the prototype version was favorable.

An interactive severe weather activity to motivate student learning

An interactive Web-based severe weather activity has been developed at Iowa State University with broad applications to motivate student learning. The exercise uses an extensive archive of weather data emphasizing warm-season severe convective events and cold-season winter storms. Several variations of the activity have been developed based upon the meteorological background of students. The flexible design of the activity may allow for its use in K–12 settings, or as a significant training tool for weather forecasters outside the classroom.

Sunspot numbers and area-weighted united states monthly temperature and precipitation

Spectral analyses were made of derived area-index series of areas subject to extreme temperatures and precipitation as well as cross-spectral analyses of the area-index series with double sunspot cycle (Zurich) numbers. Superposed epoch analyses also were made of area-index series versus various double-sunspot cycle phases. Area series for wet and dry Junes, warm Junes, defined June drought, and warm Januaries all show statistically significant double sunspot cycle (∼21 year) periodicities. The 21-year cycle of above-normal June precipitation is most striking and has not received previous recognition.

Preliminary Report of Changes in Tropopause Height Compared to Variations in Solar Behavior

A study has been made relating changes in the tropopause height to magnetic sector boundary crossings. Superposed epoch analyses did not clearly indicate a relationship. Modeling the fluctuations with a damped oscillation triggered by boundary crossings did give features varying in time which closely approximate the data.