Some sailors regard it with fear and amazement, others see it as an omen of things to come, but when I see St Elmo’s Fire burning on the masts above I am struck with curiousity for this most bizarre natural phenomenon.
St Elmo’s Fire appears as a blueish glow gracing the tips of masts and other pointy objects (lightning rods, swords, staffs, unusually long noses) during thunderstorms. You may have heard of it before, it’s been mentioned in such classics as Tintin in Tibet, Terry Pratchett’s Nation, and Moby Dick.
Despite the name, it’s not fire. It’s actually plasma, just like lightning – except instead of travelling from a cloud to the ground it just… well.. glows. It works a bit like neon lights do – energy from stormy weather (rather than a powerpoint) collect on an object and discharge. When the discharge is strong enough, it ionises gasses in the air which makes them glow. It mostly happens on pointy objects because electric fields are strongest on curves – the curvier the object, the stronger the field.
The colour is blue simply because oxygen and nitrogen glow blue when they ionise (how’s that for a circular argument? I’m sure it’s got more to do with molecular spectroscopy *shudder* more than I want to go into tonight, but if you’re curious drop me a comment.) If our air was full of neon it would be all orange, and how cool would that be?!
St Elmo’s Fire was originally named for St Erasmus – the patron saint of sailors – but whoever came up with the name should get a prize because it sounds great. Off the top of my head I can think of three fantastic things which have stolen the name. It was the title of one of the Teen Power Inc books of my childhood. As a teenager I saw the awesome 80’s movie about the twenty-somethings who tackle life and relationships after leaving college. And lately I have been listening to the old song by John Parr… I can never pick up the words except for the titular line “in St Elmo’s Fi-yar!”… I have no idea what it means in this context but for some reason (probably the science) it really resonates with me. Click through to the lyrics.
I can see a new horizon
Underneath the blazin’ sky
I’ll be where the eagle’s
Flyin’ higher and higher
Gonna be your man in motion
All I need is a pair of wheels
Take me where my future’s lyin’
St. Elmo’s Fire
Ohhhhh YEAH! St Elmo’s Fi-yah!