-->
geology

Home » Volcanoes » Volcanic Lightning

Photos of Lightning in the Redoubt Volcano Ash Cloud


Images and discussion submitted by Brentwood Higman of GroundTruthTrekking.org

These photos of lightning in a volcanic ash cloud from Redoubt Volcano were taken by Bretwood Higman. The camera was mounted under the yurt where he lives in Seldovia, Alaska, and was set to automatically take a 30 second photo every two minutes. Seldovia is 80 miles from the volcano, on the far side of Cook Inlet. Two eruptions are captured in the photos, the first at 11:20 pm on March 27, and the second two hours later. The camera, a Canon Digital Rebel XTi with a Canon 70-200mm L lens, was only barely able to resolve the eruption cloud illuminated by the lightning, which is why the images appear noisy.

Redoubt Volcano lightning
Lightning in the ash cloud from the 11:20 PM March 27 eruption at 11:26 PM. Photo by Bretwood Higman.

 Related Pages
 More Volcanoes
 Redoubt Information
For both of these eruptions, the lightning did not begin until several minutes after the explosion began. How lightning forms in general is still debated among scientists, and volcanic lightning is even less well understood. What is mostly agreed upon is that the process starts when particles separate, either after a collision or when a larger particle breaks in two. Then some difference in the aerodynamics of these particles causes the positively charged particles to be systematically separated from the negatively charged particles. Lightning is the electrical flow that results when this charge separation becomes too great for air to resist the flow of electricity. Some of the lighting strokes in these photos are at least 2 miles long, so the separation of charged particles must occur on this scale.

Ash cloud lightning
Lightning in the ash cloud from the 11:20 PM March 27 eruption at 11:28 PM. Photo by Bretwood Higman.

Lightning science
Idealized sequence of events that leads to lightning

1. Starting state (particles might have already been charged by some previous process).

2. Collisions lead to charge separation. For this to happen there has to be some difference in the electrical properties of the particles in the collisions.

3. Some process, such as aerodynamic sorting, segregates the positively and negatively charged particles. This means that there are sections of the cloud that are more negative or positive than other sections.

4. When the charge separation becomes too great, electricity will flow between the positive and negative regions of the cloud forming lightning and neutralizing the charge separation.

Volcanic lightning
Lightning in the ash cloud from the 11:20 PM March 27 eruption at 11:32 PM. Photo by Bretwood Higman.

seismogram
Timing of the eruptions relative to these photos. Image by Alaska Volcano Observatory.



Find it on Geology.com




More from Geology.com


Sliding Rocks
Sliding Rocks Mystery: What causes these rocks to slide across a Death Valley playa?
Ant Hill Garnets
Ant Hill Garnets - tiny garnets that ants haul to the surface and discard on their anthill.
Sea Level Rise Map
Sea Level Rise Map: A Google map that shows where flooding will occur as sea level rises.
Hand Lens
Hand Lens A 10-power folding magnifier in a metal case. A frequently used lab and field tool.
wall maps
Wall Maps - World maps, United States maps, continent maps, maps of individual states.
Popigai Diamonds
The Largest Diamond Deposit in the world could be under Popigai Crater in Russia.
Abandoned Mine Accidents
Abandoned Mine Accidents take 20 to 30 lives per year. Many can be prevented with education.
What Are Meteorites?
What Are Meteorites? Rocks which were once part of planets or large asteroids.





© 2005-2016 Geology.com. All Rights Reserved.
Images, code, and content on this website are property of Geology.com and are protected by copyright law.
Geology.com does not grant permission for any use, republication, or redistribution.
Images, code and content owned by others are marked on the pages where they appear.