Science & Technology

Volcanic lightning and what we can learn from the 2018 Anak Krakatau eruption

Jonathan Amos
BBC
Fri, 28 Feb 2020 12:00 UTC

The 2018 eruption of Anak Krakatau in Indonesia was remarkable in many ways.

It will be remembered, obviously, for the sudden flank collapse that triggered the tsunami which killed over 400 people on the nearby coastlines of Sumatra and Java.

But the event also has been the source of many scientific insights that could inform future hazard assessments.

And a new possibility is the potential for the frequency of lightning seen at an eruption to give a simple guide to the height of a volcano's towering plume.

It's information that could be of interest to airlines trying to find safe routes for their planes.

Anak Krakatau had a huge eruption cloud that climbed 16-18km into the sky and which then levelled out into the classic anvil shape familiar from meteorological thunderstorms in the tropics.

Driving this tall convection column was the particular circumstances of the eruption.

When the wall of the volcano failed, it allowed seawater to come into direct contact with magma.

The result was a series of spectacular explosions that sent steam and ash rushing upwards.

Satellite observations indicate the "wet ash" fell back relatively quickly, but that much of the water vapour continued skyward, where it formed the anvil-topped plume that persisted for six days.

And, of course, as the water went higher and higher it eventually turned to ice in the sub-zero temperatures at altitude.

Dr Andrew Prata, from the Barcelona Supercomputing Center in Spain, and colleagues have calculated the mass of all this ice - and the numbers involved are really quite impressive.

On average, there was three million tonnes hanging above Anak Krakatau. Up to 10 millions tonnes at the peak of ice production.

What's more, the movement through the plume of all this frozen material - some of it going up, some coming down - appears to have initiated a frenzy of lightning.

Approximately 100,000 strikes were recorded by sensors in those six days following the onset of the explosive phase of the eruption.

Over 70 flashes per minute at one point, says Dr Prata, whose team has just published its findings in the journal Scientific Reports.

"And what was interesting about that is that we started to see a relationship between the flash rate in the eruption plume and the height of the plume," he told BBC News.

"So, essentially, the greater the flash rate, the higher the plume. This is something that could be important and useful for aviation."

© Copernicus Data 2019
Copernicus Data 2019 Image caption Anak Krakatau (centre island) lost its western flank on 22 December 2018

Planes need to be wary of flying through or near the eruption columns of volcanoes because of the damage fine ash can do to jet engines.

Airliners have experienced "flame-outs" in flight after their engines have ingested too much ash.

Dr Rebecca Williams from Hull University, UK, has been conducting her own research into the Anak Krakatau event.

She described the Spanish-led study as "fascinating", and agreed that it could assist volcano monitoring.

"Using lightning to detect volcanic eruptions is an emerging technique," she said.

"This study is a very important contribution to this - it correlates volcanic lightning data with volcanic cloud height in an ash-poor, ice-rich plume.

"This will be important in monitoring volcanic eruptions, particularly in remote areas which may impact aviation routes."

Comment: Could it be that as the plume rises higher as well what it's composed of increases the potential for a discharge event between the ground and the atmosphere?

Some clues as to what may be happening may be found in the following extract from Pierre Lescaudron's book Earth Changes and the Human-Cosmic Connection:

Lightning and hurricanes seem to be similar charge rebalancing processes. Lightning mostly occurs above continents and is far less frequent above oceans.¹ This may be due to the difference between ground conductivity and sea conductivity. When electrons start flowing upwards from the ocean, the high conductivity of salt water² usually prevents the formation of electron-deficient regions, which is one of the causes of lightning. However, when the upward electron flow occurs above a continent, the poor conductivity of the ground³ enables the formation of electron-deficient pockets that will trigger and receive lightning discharges.

In terms of location, hurricanes are the opposite of lightning bolts: they mostly occur above oceans and usually weaken or die when they reach land. When a massive flow of electrons is pulled up above the ocean, the high conductivity of salt water can provide and conduct free electrons from all adjacent regions, thus offering an almost endless supply of electrons to power the ongoing hurricane. When the hurricane reaches the ground, the electron supply is limited by the poor conductivity of the ground and the hurricane weakens.

[...]

Notice also that the rainfall that usually accompanies hurricanes also participates in the charge re-balancing process.

When a water drop falls to the ground, it can capture electrons from the bottom of the cloud or below it, thus carrying a negative charge to the ground and rebalancing electric potential differences in a manner similar to lightning. From this perspective, lightning and rain are both caused by a strong atmospheric E-field and both lead to a charge rebalancing between the Earth's surface and its atmosphere.

Notice that the atmospheric field has an influence on raindrops formation and size. In the image below,⁴ a thin water jet was created by a hypodermic needle connected to a water faucet. On the left, no electric field was applied. The jet took the form of a mist made of small droplets. On the right, an electric field was applied to the water jet, triggering the binding of droplets with each other and the subsequent formation of large water drops. This experiment is very similar to what occurs in clouds, where water droplets tend to align along the atmospheric E-field and attract each other, forming heavier and heavier water drops.

© Pierce Bounds
Influence of electric field on the size of water drops.

From the above we can see that lightning and hurricanes are very similar electric phenomena. Hurricanes are to sea surface what lightning bolts are to ground surface. They are both caused by upward electron flows and they both rebalance electric charges by returning electrons to the ground: rainfall in the case of hurricanes, lightning in the case of electrical storms.

Before closing this chapter, a few further comments about atmospheric dust are necessary: as we've seen previously, atmospheric dust plays a major role in storm dynamics. On a physical level it acts as a nucleus for the formation of condensed water droplets (clouds). On an electrical level it holds electric charges that can trigger lightning.

Atmospheric dust also seems able to modulate cloud elevation. According to mainstream science, atmospheric dust and water droplets stay in suspension in the atmosphere because of their very small size, exhibiting low weight and comparatively large drag.⁵ However, some observations don't fit the gravity-drag model and, in some cases, dust clouds settle much slower than predicted:
Interestingly, it appears that some hitherto unknown atmospheric process counteracts gravitational settling of larger atmospheric dust particles (Maring et al., 2003), as models of long-range dust transport often underestimate the larger particle fraction (Colarco et al., 2003, Ginoux et al., 2001), and dust samples collected after fallout events show that large numbers of 'giant' dust particles (larger than 62.5 micrometers) can be carried thousands of kilometers from their source (Middleton et al., 2001).⁶⁷
If you remember the Millikan experiment⁸, a droplet charged with only one electron can counteract gravity and literally levitate when exposed to a vertical electric field. For this to happen, the vertical electric field has to be 32,100 v/m.⁹ Although the atmospheric electric field is normally about 100 v/m at ground level,¹⁰ atmospheric dust or atmospheric droplets, because they reduce conductivity, can drastically increase this value. Electric fields of 2,000 v/m have been measured under dust storms,¹¹ up to 20,000 v/m has been observed under thunderstorms¹² and up to 200,000 v/m within thunderstorms.¹³ In addition, unlike the Millikan experiment, some particles can carry more than one electron charge.

This means that the atmospheric electric field can play a role in the fall speed, location, movement and elevation of clouds whether they are made of dust or droplets (or both). It can cause the particles to 'levitate' or literally rise up in the air.

Reader Comments

Rowan Cocoan · 2020-03-01T17:56:45Z

In the past, when reading 'official versions' of physics, etc., (and especially when they denigrate the value of a more electrically based analysis), I've found myself thinking about volcanic lightning to question some of the 'official' version's points, but I forget what it was in particular. Oh well.

binra · 2020-03-01T22:24:37Z

Yes - The Electric Earth (In Electric Space) also initiates convective and pressure-kinetic processes - that the general theory and mindset take as the primary causes.

Vulcanism itself is in my opinion a primarily electrically activated event. There are huge ground currents that interact with ionosperic charge and 'space weather'.

The old view is a magnetosphere as a closed system - while Sol (our Sun) is presumed to be a nuclear explosion (closed system).

The thing about closed system thinking is its inversion or reversal of Consciousness - in putting cause and power in the object or energy into matter as motion.

From a 'thing' mind, we do not see the results of the Field of Relation nor feel our own true inherence.