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Michael Wilkinson Seeking Answers to How Storms Form Program Title: Chasing El Niño | Hurricane Subject(s): Earth Science Grade Level: 6

Michael Wilkinson works with students to interpret graphical weather data.

Wilkinson took advantage of his students' interests in real-time storm tracking to help them understand what causes storms to form.

Wilkinson, a 17-year veteran educator at the Fieldston Lower School in the Bronx, New York, adapts his climatology unit each year to respond to current events and students' interests. Wilkinson says the key to an inquiry-driven curriculum is feeling comfortable enough with the content to be flexible in how the curriculum gets pieced together.

Wilkinson's climatology study begins with students tracking the Atlantic storm season and studying the link between storm formation and sea surface temperatures (SST). Wilkinson has student analyze SST data that he posts on the Web for easy access from school or home. This leads to a discussion of the factors that influence storms. By looking at data within and outside of the normal expected ranges, students identify the pattern of surface ocean water circulation in the Atlantic Ocean.

A series of lab investigations in convection, condensation, and the Coriolis effect help students make sense of ocean current patterns. From these three lab investigations, students revisit their SST maps to see that a minimum surface temperature of 27° C (80° F) is necessary for hurricane formation.

To help students understand how seasonal changes affect sea surface temperatures, Wilkinson demonstrates how the sun's influence on Atlantic waters shifts with the seasons. First, he marks New York City on a globe with a pushpin. The class then takes the globe outside at 12 noon and aligns it to match Earth's orientation. The shadow of the pin now points north along the local meridian. Doing this activity at different times during the year (e.g., equinoxes or solstices) helps students see the marked differences in where the shadow crosses in the polar regions. (At the equinox the shadow crosses through both poles. At the solstice one pole will be completely dark while the other is completely in the sun.)

Students return to their SST maps and find that the warm spot shifts through the year, moving into the 20-30° N Latitudes by peak hurricane season. They also notice that the Atlantic begins to cool in September as the hurricane season wanes.

The understanding that sea surface temperatures are seasonal provides a springboard to looking at ocean current patterns in the Pacific Ocean and how the Pacific affects global weather. Students use the Tropical Atmosphere Ocean Project Web site to examine monthly data of sea surface temperatures for the years 1991-present. The SST maps are then used to identify patterns of heating and cooling. Students can see seasonal fluctuations in SST caused by the migration of the sun north and south through the tropics between solstices. Once students understand what the norm is, they look at SST anomaly maps and identify significant deviations. These two activities enable students to identify El Niño-Southern Oscillation (ENSO) events, La Niña, and normal tropical Pacific conditions.

The NOVA programs "Chasing El Nino" and "Hurricane" are used either when students discuss remote sensing data or begin to talk about ENSO. Wilkinson says that the NOVA programs provide students with an opportunity to safely observe the nature of storms, give them a context through personal narratives, and expose them to various careers in science.

Wilkinson says that one outcome of an inquiry-driven curriculum is that students are empowered knowing that they use the same data as meteorologists. Another benefit is that students' work with the primary source data and meteorological reports enables them to problem solve and explain anomalies in data. "It's really cool working with all this information because you have to work back and forth with different kinds of information," says one of Wilkinson's students. "You have to learn how to read the information and figure out what it means."

For more information about Wilkinson's unit, you can e-mail him at:

—Kristina Ransick

Resources

National Weather Service
www.nws.noaa.gov/
Provides access to local weather for comparison of conditions around the country and world.

NOAA
www.noaa.gov/
Contains current and archived satellite and synoptic data for tracking tropical storms and ENSO. Includes links to the National Hurricane Center and NOAA weather radio.

NOVA's Chasing El Nino!
shop.wgbh.org/
Examines the effects of past and present El Niños on global weather and follows the work of scientists who are trying to understand and predict this phenomenon.

NOVA's Hurricane!
shop.wgbh.org/
Shows how scientists fly into the world's most destructive storms to discover what makes them tick and provides first-hand accounts of Hurricane Camille.

Tropical Atmosphere Ocean Project
www.pmel.noaa.gov/tao/
Provides real-time data from moored ocean buoys for improved detection, understanding and prediction of El Niño and La Niña.

Weather Underground
www.weatherunderground.com/
Contains current and archival weather data including a section devoted to tropical weather. Tropical weather page includes daily SST map and links to all Atlantic storms for the past century.