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Volcano Solar Transmission Exercise

submitted by

Laura A. Guertin Penn State University Delaware County
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This is a partially developed activity description. It is included in the collection because it contains ideas useful for teaching even though it is incomplete.

The activity begins in the classroom with students graphing and interpreting apparent volcanic solar transmission values collected at Mauna Loa Observatory, HI. Students finish the exercise outside the classroom by investigating the dates of significant decreases in solar transmission and matching those dates to volcanic eruptions.
GSA Poster (PowerPoint 2.5MB Oct30 03)

Learning Goals


Higher Order Thinking Skills:

drawing conclusions from data, investigating cause/effect relationships

Other Skills:

graphing, writing


Instructional Level:

undergraduate entry level

Skills Needed:

none - except being able to manually plot data and search the internet

Role of Activity in a Course:

In a physical geology course, two lectures are given on volcanism and igneous processes, one additional lecture is given on Kileaua and its current eruptions. The next class period is when this activity is conducted. The activity can be in a laboratory or during a lecture session.

Data, Tools and Logistics

Required Tools:

one overhead projector, transparency sheets and markers, apparent solar transmission data set

Logistical Challenges:

students plotting the data incorrectly, students coming late to class or not attending


Evaluation Goals:

Evaluation Techniques:

a grading rubric has been developed and is provided to the students the day of the activity


An interactive lecture and graphing exercise has been developed for an introductory-level physical geoscience course where students work with apparent solar transmission data. When lecturing on volcanism, I discuss volcanic influences on climate that can be seen in a Mauna Loa Observatory data set. Data has been compiled since 1958 of monthly averages of apparent solar transmission values which have been calculated from direct solar irradiance observations.

During a class period, students work in pairs plotting the apparent solar transmission value for a given month and year. Students graph the data on an overhead transparency sheet and answer a series of questions about trends and predictions for future data. All transparencies are overlain on an overhead projector. As a class we discuss features we see in the compiled graph, such as the notable decreases in the transmission values which they do not know at this point coincide to the timing of three major volcanic eruptions (Agung in 1963, El Chichon in 1982, Mount Pinatubo in 1991).

At the conclusion of the in-class exercise, students are required to type a summary explaining the graph. Students must clearly explain why there are the significant decreases in transmission. Students are asked if there are any other decreases in the transmission ratio they are surprised are not reflected in this global data, and they are required to use references to support their interpretations and discussion. The summary must also discuss Kilauea, and a statement as to why or why not the eruptions will be recorded in the solar transmission ratio data.

I use this exercise as the first where students work with graphing and interpreting a data set; consequently, student performance has been wide-ranging. Most groups accurately plot the data in class. Some students do not accurately correlate the dates of solar transmission decreases with volcanic eruptions. In addition, a number of students do not know how to apply what they have learned about Kilauea. Despite the range of student performance, this exercise serves as a valuable introduction to the global impact of physical processes and how to interpret that impact through working with data.

* The format of this exercise is a modification from Randall Richardson's (Univ. of Arizona) homework problem using the global CO2 data set from Mauna Loa, Hawaii.

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