White lightning?

[drew]

Weather turned dog on us here in the Naki this arvo with the temperature taking a real dive.
We have had heaps of hail and very heavy squalls pass through.

One thing has me curious though.

My wife was outside said she witnessed two very bright, extremely pure white flashes of lightning, each of which followed by massive deep thunder claps. I heard the thunder, but did not see the lightning.

Then just now there has been some more, which I have seen out to the east, and indeed the lightning flash is extremely white, enough so to warrant comment by my wife (who doesnt have much interest in this stuff) and has raised my curiousity enough to ask the group..

Is this extremely white lightning a depature from the norm or just something not often seen round here?

It is very bright and lights up most of the sky.

Its also very sureal as above us is a 3/4 moon, very bright, with lots of stars, but not far east huge CB's can be seen trucking past...

Thanks
Drew

[NZstorm]

My own opinion is that all lightning is the same colour but associated clouds/precip and anything else in the atmosphere such as pollution....could colour it for the observer.

[Tornado Tim]

Totally agree with you NZstorm.
Its to do with Optics and the structure of the element that is causing the difference colors of lighting.
White Lightning has been well associated with low humidity conditions (or the air between the cloud and ground or wherever it struck)

[Manukau heads obs]

yes, sounds like sheet lightning, i.e reflected light from the clouds, etc
i.e certain cloud layers and heights and type will play a part I would say

my boltec tracker picked up a good number of strikes in taranaki yesterday, lucky you!

[ricky]

Also subjectively influenced by the local environmental lighting, If your eyes have become accustomed to more yellow lighting indoors, from streetlights or from light reflecting or filtering through the cloud then the lightning will appear a lot more blue or white.
Having said that I have observed some variation in c-g lightning colour from the same storm, i assumed relating to the current density of the strike

[Vertigo]

interesting, most of the lightning ive observed in new zealand takes on a purple hue. perhaps this is due to the nitrogen in the atmosphere?

[Paul Mallinson]

Just thought I would add my 2 cents.

I think many of the points made are probably applicable. One thought I have is that (as ricky mentioned) it may depend also upon the voltage/current of the flash. In other words a weak flash may be a cooler flash than a very high voltage/current discharge. The hotter the object, the bluer/whiter the emitted light. For example, stars are like this. Cool stars emitt down the red end of the spectrum and hot stars up the blue end. But ofcourse, even the 'cool' flashes would still be bright to the human eye but some sense of colour shift may come through.

Paul

[Andrew Massie]

Just thought I would add my 2 cents.

I think many of the points made are probably applicable. One thought I have is that (as ricky mentioned) it may depend also upon the voltage/current of the flash. In other words a weak flash may be a cooler flash than a very high voltage/current discharge. The hotter the object, the bluer/whiter the emitted light. For example, stars are like this. Cool stars emitt down the red end of the spectrum and hot stars up the blue end. But ofcourse, even the 'cool' flashes would still be bright to the human eye but some sense of colour shift may come through.

Paul

I agree with this. Video I have slowed down shows some pinky/purple lightning, and then others (particularly the straight down CGs) are very white with a bluey tinge. A CG obviously is very high in voltage and current (and thus, power, which is the product of voltage x current) as it actually reaches earth by overcoming the resistance of air (air being the dielectric).

Our Tesla coil at CPIT produces a million volt arc that jumps a 1m gap, but only produces 17 microamps. It is usually quite purple in tone. Must post a video of it!

[RODALCO]

Most lightning strikes have a current of about 20,000 Ampères and a couple of million Volts.