1 Oct 2014

Potten End Newsletter Article 17

This article originally appeared in the Potten End Newsletter, October 2014.

Potten End Weather

““Life is not about waiting for the storms to pass. 

It’s about learning how to dance in the rain.” 

― Vivian Greene

About a year ago I wrote a short article about lightning. Since then, after much research I found that I’d barely scraped the surface of the subject. Indeed, some of the results of research in to lightning had not been published when that article was written.

The science of lightning is called fulminology, and the fear of lightning is called astraphobia. Hopefully this article will spark (sorry) some interest in fulminology which may help reduce any astraphobia.

Lightning is not distributed evenly around the planet. About 70% of lightning occurs over land in the tropics where the temperature difference and lack of stability within the atmosphere is greatest.

There are three primary types of lightning that we’re all fairly familiar with: from a cloud to itself (intra-cloud or IC); from one cloud to another cloud (CC) and between a cloud and the ground (CG). IC and CC are more common types of lightning, but CG is the most studied and understood.

There are a number of more rare and elusive types of lightning that are all fascinating in their own right.

Invisible Lightning

Not all lightning is visible. Sometimes, extremely intense bursts of energy are produced high up in a thundercloud. These bursts of energy are called Terrestrial Gamma-ray Flashes or TGFs. These TGFs are millions of times more powerful than normal visible lightning. TGFs were first discovered in 1991 and only properly observed in 2009. Their precise relationship to visible lightning remains a subject of ongoing scientific study. Fortunately the gamma rays are directed out in to space and don’t pose any problems to people on the surface of the planet.


ELVES appear above thunderstorms as a very brief dull flattened disk of dim light around 250 miles in diameter at an altitude of over 60 miles. They were first recorded from the space shuttle orbiter Discovery in 1990. ELVES is an amusingly tortuous acronym for Emissions of Light and Very Low Frequency Perturbations due to Electromagnetic Pulse Sources.


Sprites are large scale electrical discharges that are red in colour and appear above a thundercloud at altitudes between 30 and 60 miles. Sprites were named after the rascally sprite Puck in William Shakespeare’s A Midsummer Night’s Dream.

Blue Jets

Blue Jets are a type of sprite that appear from the top of a thundercloud and project up to 25-30 miles above the earth in a conical shape. They were first recorded from a space shuttle orbiter Atlantis in October 1989 as it passed over Australia. They are far rarer than sprites and do not appear to be triggered by a lightning strike. By 2007, less than 100 images of Blue Jets existed, the majority of which came from a single thunderstorm.

October Expectations

September marked the beginning of the meteorological autumn and, barring an Indian Summer, we can expect to fully notice the autumnal weather in October with shorter days, longer nights and a distinct chill and dampness creeping in. On average we can expect to see daytime high temperatures between 7.5ºC and 15ºC though we have seen a high of 25.3ºC in 2011.


I would like to dedicate this to the memory of friend and neighbour Peter Griffiths who  inspired and motivated me to write this series of articles on weather. He will be greatly missed.