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📘 How lightning can start upward

You stand beneath a storm. A tower can send a faint, branching leader upward first, reaching toward charged air above. The bright flash may begin at the ground.

4
lessons
~20 min
to learn
Adults
level
Start the course →

What you’ll learn

  1. A storm seen from the groundDistinguish upward lightning from the more familiar cloud-to-ground pattern and identify why direction describes a leader's growth.Lightning can begin with a leader rising from a grounded object, even though the later bright flash is a completed circuit.
  2. Why height changes the oddsExplain how height, sharp geometry, terrain, and changing storm fields make upward initiation more likely.Towers and summits concentrate electric field and shorten the gap, but storm conditions still decide whether a leader begins.
  3. What travels up and what comes backSeparate leader direction, polarity, return stroke, and continuing current in an upward discharge.A staged leader process creates the channel; connection and current produce the bright return stroke and possible continuing flow.
  4. Why researchers careConnect upward-lightning observations to tower research, wind-turbine engineering, and practical protection systems.Instrumented structures reveal the event while protection systems manage its current, and many questions remain open.

Questions this course answers

What makes a tall tower more likely to initiate an upward leader?

Height brings the structure closer to charged regions, while sharp geometry concentrates the electric field.

In upward lightning, what usually happens before the brilliant main flash?

Leaders grow through the air and the completed connection enables the large current that makes the channel bright.

Put the stages of an upward flash in a sensible order.

The structure changes the local field first, then leader growth and connection allow the larger current stage.

Why is a lightning rod not a guarantee that lightning will never strike a building?

A protected structure can still be part of the discharge, but bonding, conductors, grounding, and surge protection reduce the risk of uncontrolled current.

Grounded in trusted sources

  • National Weather Service, Understanding Lightning: Upward Leaders/Discharges. https://www.weather.gov/safety/lightning-science-upward-leaders
  • National Weather Service, Understanding Lightning: Initiation of Leaders. https://www.weather.gov/safety/lightning-science-initiation-leaders
  • Zhu et al., Evolution of an Upward Negative Lightning Flash Triggered by a Distant +CG From a 257-m-Tall Tower, Geophysical Research Letters. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL083274
  • Pineda et al., Meteorological Aspects of Self-Initiated Upward Lightning at the Säntis Tower, Journal of Geophysical Research: Atmospheres. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JD030834
  • Wang et al., Characteristics of upward lightning from a 325-m-tall meteorology tower, Atmospheric Research. https://doi.org/10.1016/j.atmosres.2014.06.007
  • Jerauld et al., Physical processes during development of upward leaders from tall structures, Journal of Electrostatics. https://doi.org/10.1016/j.elstat.2011.01.003

Every Wunder lesson is built from real, reputable sources — never invented.

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