The Glowing Forest: Lesson Plan
Overview
This lesson uses the 271-year journey from Richmann's fatal lightning experiment to the first filmed observation of corona discharges on trees to explore atmospheric electricity, the scientific method, and how technological limitations shape what science can discover.
Subject areas: Physics, Earth Science, History of Science, Atmospheric Science Grade levels: 9-12, AP Physics, AP Environmental Science Duration: 1-2 class periods (45-90 minutes)
Essential Questions
- How does technology determine what science can observe?
- Why did it take 70 years to confirm something scientists already suspected?
- What is the relationship between risk and discovery in experimental science?
- How does atmospheric electricity connect the Earth to the sky?
Learning Objectives
Students will be able to:
- Explain corona discharge and its relationship to electric fields
- Describe the global atmospheric electrical circuit
- Compare historical and modern methods of studying atmospheric electricity
- Evaluate how instrument limitations constrain scientific observation
- Trace the evolution of understanding atmospheric electricity from ancient sailors to modern researchers
Key Vocabulary
- Corona discharge: Electrical current leaking from a pointed conductor into surrounding air
- St. Elmo's fire: Visible corona discharge observed on ship masts, steeples, and other pointed objects during storms
- Electrometer: An instrument for measuring electrical charge or potential
- Ball lightning: A rare atmospheric phenomenon involving luminous spherical objects during thunderstorms
- Ionization: The process of converting atoms or molecules into ions by adding or removing electrons
- Global electrical circuit: The continuous flow of electrical charge between the Earth's surface and the atmosphere
Activities
Activity 1: The Observer's Dilemma (15 min)
Present students with the challenge: "You suspect that every tree in a forest glows with invisible electricity during a thunderstorm. Design an experiment to prove it." Discuss constraints: you can't see the glow with the naked eye (it's ultraviolet), you need to be outside in a thunderstorm, and your equipment needs to survive.
Compare student proposals with the Penn State team's solution: a converted minivan with a UV camera on the roof.
Activity 2: 2,000 Years of Observations (20 min)
Build a timeline of atmospheric electricity observations:
- 1st century: Pliny the Elder describes St. Elmo's fire
- 47 BC: Julius Caesar notes it during African campaign
- 1493: Columbus's crew reports it at sea
- 1752: Franklin proposes lightning is electrical
- 1753: Richmann killed measuring atmospheric electricity
- 1832: Darwin observes it on the Beagle
- 1950s: Scientists theorize forests produce corona discharges
- 2024: Penn State team films it for the first time
Discuss: What changed between each observation? (Instruments, theory, technology, courage?)
Activity 3: Build a Corona Discharge Detector (20 min)
Using a Van de Graaff generator and pointed conductors (needles, pins), demonstrate corona discharge in the classroom. Students observe the faint glow in a darkened room and measure the effect with a simple electroscope.
Activity 4: Risk and Discovery (15 min)
Discuss Richmann's death in the context of scientific ethics and safety:
- Was Richmann reckless or brave?
- How do modern safety protocols differ from 18th-century practice?
- Name other scientists who died or were injured in pursuit of discovery
- How does the Penn State team's approach (a minivan, a parking lot) compare with Richmann's (an iron rod in his study)?
Assessment Options
- Essay: "It took 271 years and a Toyota Sienna to see it." What does this statement reveal about the relationship between technology and scientific discovery?
- Lab report: Design and conduct an experiment demonstrating corona discharge. Document observations and relate them to the atmospheric phenomenon.
- Research project: Investigate the global atmospheric electrical circuit. How much current flows between the Earth and the atmosphere? What role do thunderstorms, forests, and oceans play?
Extension Activities
- Research ball lightning, the phenomenon that killed Richmann. Why is it still poorly understood 270 years later?
- Investigate how corona discharge affects power lines and aircraft. Why do high-voltage lines sometimes glow at night?
- Calculate the total electrical current that forests might contribute to the global atmospheric circuit based on the Penn State findings.