Welcome back steemians! Another post on a strange phenomenon is here to feed your mystery-thirst and I hope you'll enjoy it as much as all the others.

Imagine being on a ship sailing across the seas at night. As you sit on the deck gazing at the vast sea spreading before your eyes, your look is turning up to the sky and the bright stars above you, but then you spot something you find hard to believe... an eerie blue-ish fire over the ship's masts! Before you start panicking and looking for a fire extinguisher, I'll tell you to relax and just enjoy the sight, because this is only a rare phenomenon called Saint Elmo's fire (don't worry, although it has the word fire in it it doesn't burn, the danger usually comes after it).

(Image source: wikipedia.org)

What is it?

As weird and supernatural as it might look, this rare weather phenomenon has a very logical explanation. Well, to break all the mystery at once, St Elmo's fire is actually plasma! Yes, this magnificent state of matter we saw in some of my previous posts. Now, let me explain how it's done.

Pretty much like in a neon light tube, this outworldly light comes from the ionization of the atmosphere during a storm. Around that time there is a great voltage differential between the differently charged clouds and the ground. This creates the perfect conditions to increase the air's conductivity by releasing a discharge of electricity and turning the air into plasma*.

* For those that don't remember, plasma is basically a form of ionized gas, where atoms have lost some or all of their electrons and differently charged particles float around (negatively-charged electrons and positively-charged proton nuclei). This happens because of a dramatic rise in temperature or the applying of an electrical current (like in our case here). The result is a great conductor that allows electricity flow within it and produces colored light.

(Image source: wikimedia.org)

St Elmo's fire is basically triggered by the voltage differential between the ionized air and a present lightning conductor (a ship's mast, a lightning rod or a plane's wing). When voltage gets as high as about 30.000 volts/square centimeter around the lightning conductor, the positively-charged proton nuclei within the plasma will act like a "magnet" drawing the lightning conductor's electrons towards them. This clashing encounter will excite the air molecules even further. As electrons frantically move around inside the plasma, they suddenly return back to their relaxed state releasing a photon and occasionally a hissing sound (think of it like a tiny meteor's flashing light), their light usually lasts for a few minutes. Note that, spiky objects might trigger the phenomenon in even lower voltages, that's why the phenomenon is mostly observed around masts, plane wings and church steeples.

(Image source: pixabay.com)

Different gases give off different colors. Because of the air's composition (presence of oxygen and nitrogen) the light that glows is blue or purple. If there was neon in the atmosphere, the light would be red. That's why we use different gases in fluorescent light bulbs to get different light colors.

Who is Saint Elmo?

Saint Elmo is basically Saint Erasmus of Formia, the patron saint of sailors. The phenomenon was considered a good omen as it was viewed during storms. When the storm was coming to an end the sailors believed it was the saint having heard their prayers and answering them by keeping the crew safe. That's why they named the phenomenon after him. Saint Elmo is actually a mishearing of Saint Ermo, another name for Saint Erasmus.

(Image source: wikipedia.org)

Its appearance in human history

The phenomenon has widely been observed throughout history and there are several references from times as old as the ancient Greece (silently bursts with pride about her ancestors). Other mentions by widely famous people include Julius Caesar, Pliny the Elder and Ferdinand Magellan. In modern times, there have also been numerous reports of it, some of which you can find here.

Why is it a dangerous omen?

Whereas St Elmo's fire is harmless, it wouldn't be wise to consider it a good sign as it usually precedes lightning. The conditions before its appearance are perfect to generate great electrical discharges in the form of lightning, burning to the ground anything (or anyone) that finds themselves in the unlucky place of substituting a lightning rod.

(Image source: flickr.com)

Here's a 5-minute video presenting the phenomenon in detail:

https://www.youtube.com/watch?v=KO41oHaNjCE

St Elmo's fire DIY:

In this video you can see how to create a glow discharge at home (go to: 2' 44'')

https://www.youtube.com/watch?v=0KhDzzCiEWc

References

scientificamerican.com
science.howstuffworks.com
sciencefacts.net
physicsbuzz.physicscentral.com
wikipedia.org_1
wikipedia.org_2

Thank you for stopping by and giving this post a read. I hope you enjoyed it!

If it got your curiosity-radar on, feel free to follow me, @ruth-girl, for more fascinating phenomena!

You can also check some of the previous articles on this series:
15 - Ice Brinicles
16 - The Clone Forest
17 - A Skypunch
18 - Lake Baikal
19 - Mother-Of-Pearls Clouds
20 - The Hessdalen Lights

And for those engaging with education, @steemiteducation is here to join all steemian educators in their common cause of making our job easier, more effective and more fun, because...

(Original image credits: Nick Youngson - nyphotographic.com)

Finally, the greek community of steemit is here and waiting for you to discover it! Follow the @greek-trail for daily doses of good-quality posts by wonderful writers!

Until my next post,
Steem on, people, and keep smiling!