Greenage (Conditions leading To)

[Dustin Wilcox]

Figured we all should know, as it is an extremely valuable tool leading to Tornadoes... No?

But Really... With a storms structure/nature, angle of the sun, and position relative to the two in mind, what is an ideal scenario for the greenish/blue tint that often is visible? You always see it, sometimes just much more vibrant than others, with the understanding that each and every case is going to considerably different, there has to be a rather basic set of conditions leading to the display; and based on those, an “ideal” place to position to maximize the show. Recalling a few of the crazy Greenage displays I've seen and looking back at some photos, has got me envisioning some pretty sweet shots; better understanding the physics behind the display will only allow me to have a better shot at maximizing the potential!

 

[Brian Stertz]

Dustin...greenage is nice but tornado black even better. Greenage seems to be tied into a combo as you've said and probably has alot to do with the sunlight coming in in the RFD hole area. Tornado black is one that I have seen three times, and all three times it was with violent tornadoes....May 3, 1999....May 12, 2005...April 8, 1999.
This is that super low black cloud base with a certain dark haze tint. Thats when I know that sh*t is hitting the fan.

 

[rdale]

Figured we all should know, as it is an extremely valuable tool leading to Tornadoes... No?

No. Green skies can occur (and do very often) without a tornado.

http://www.wsaz.com/blogs/askjosh/42602272.html

More technical:

http://ams.allenpress.com/perlserv/...039<1754:DGTFST>2.0.CO;2&request=get-document

 

[Chad Cowan]

No. Green skies can occur (and do very often) without a tornado.

http://www.wsaz.com/blogs/askjosh/42602272.html

More technical:

http://ams.allenpress.com/perlserv/...039<1754:DGTFST>2.0.CO;2&request=get-document

Pretty sure that was a tounge-in-cheek statement... hence the "But really.." in the next sentence.

 

[Bart_Comstock]

Do not reley on seeing a green tinted sky as a precurser to a tornado. The green sky and a tornado can happen independently of tornadoes and vise versa. The green sky can also be seen from diffent angles of the storm and is often visible in areas where a tornado will not form.

It is formed by light filtering through the storm. It is a good indicator of very deep convection and can sometimes be a sign of large hail. It is often seen under a HP supercell where large amounts of precip can be found.

mods: shouldn't this be moved to the educational forum?

 

[Chad Cowan]

Apparently sarcasm is difficult to pick up on Fridays.

 

[Dustin Wilcox]

Apparently sarcasm is difficult to pick up on Fridays.

LOL, not sure I could have made it any more obvious without first stating "this is sarcastic" and ending the sarcastic part with "sarcasm over" I'm more than well aware Greenage isn't a first indication of a tornado or any indication for that matter. I'm too well aware of the essential principles as far as light and it's reflection being the foundation for the phenomenon, and where the color can most often be seen. The thread was started with hopes of hearing some discussion, some scenarios and further more, angles, signs to look for, ext. that appear to be more conducive for witnessing the phenomenon.

 

[Andrew Ryan]

When I first read this thread, I thought you were talking about vegetation and the effect of evapotranspiration on tornadoes.

But any-who, I see "greenage" on pretty much every chase I go on. I just see it as a sign of large hail.

Also, I've never seen "tornado black" but I really never thought of the correlation between tornado contrast and strength. Depending on the angle you view the tornado from, the contrast could change. Interesting none the less.

 

[rdale]

The thread was started with hopes of hearing some discussion, some scenarios and further more, angles, signs to look for, ext. that appear to be more conducive for witnessing the phenomenon.

Gotcha. Sarcasm missed (maybe due to the fact that one guy keeps emailing me every time he sees green skies wondering why we don't have a tornado warning in effect )

In any case, I'm pretty sure that AMS article should answer a lot of your questions on sun angles / lighting / etc. Especially the articles mentioned in the references.

PS I did think this was going to be about evapotranspiration too)

 

[Skip Talbot]

You always see it, sometimes just much more vibrant than others, with the understanding that each and every case is going to considerably different, there has to be a rather basic set of conditions leading to the display; and based on those, an “idealâ€￾ place to position to maximize the show.

There are a large number of variables that cause the colors we see while chasing. I think the biggest contributors are the angle of the sun, and the path through the storm this light takes. It seems to me that when the sun is at a 45 (later afternoon/early evening) the sun is a very yellow color (due to blue absorption by the sky). The precipitation in a storm typically absorbs the red and yellow wavelengths leaving a blueish color (similar to what you see underwater). If this yellow sunlight is being scattered, it would create green hues against the blue precipitation. Earlier in the day (noon) you'll see more of a deep a blue as the sun's light is closer to white (experiencing less absorption) and the rays are going to pass straight down through the entire length of the storm where they'll see the most absorption. At sunset the sun is often very red, and you can see a lot of orange, sepia, or brown tones.

I think a south or southeast position on the storm is going to be the best angle for viewing these hues as you'll see the most intense precipitation with the clearest air in front of you. Using the green hues in your shots can make a dramatic background, but I think you might suffer poor contrast many times trying to put the tornado between you and the greenage. When the contrast is there, however, it will make for a dazzling shot. I probably wouldn't do anything differently. Being just east or southeast of a tornado will give you the most flexibility to get the shot you want.

mods: shouldn't this be moved to the educational forum?

It should be fine here. The original post was more about the properties involved in storm colors and how best to maximize their photographic qualities.

 

[Dustin Wilcox]

http://ams.allenpress.com/perlserv/...039<1754:DGTFST>2.0.CO;2&request=get-document

Good read, but mainly rebuts, or at least downplays a theory; rather than discussing and explaining viable theories.

 

[Bart_Comstock]

LOL, not sure I could have made it any more obvious without first stating "this is sarcastic" and ending the sarcastic part with "sarcasm over" I'm more than well aware Greenage isn't a first indication of a tornado or any indication for that matter. I'm too well aware of the essential principles as far as light and it's reflection being the foundation for the phenomenon, and where the color can most often be seen. The thread was started with hopes of hearing some discussion, some scenarios and further more, angles, signs to look for, ext. that appear to be more conducive for witnessing the phenomenon.

Well this would have all been avoided if you had rememberd your [sarcasm][/sarcasm] tags.

 

[rdale]

I think many of these discuss the theories behind green storms:

• Bohren, C. F., 1995: Optics, atmospheric. Encyclopedia of Applied Physics. Vol. 12. VCH Publishers, 405–434..
• ——, and A. B. Fraser, 1993: Green thunderstorms. Bull. Amer. Meteor. Soc., 74, 2185–2193..
  
• Fankhauser, J. C., G. M. Barnes, L. J. Miller, and P. M. Rostkowski, 1983: Photographic documentation of some distinctive cloud forms observed beneath a large cumulonimbus. Bull. Amer. Meteor. Soc., 64, 450–462.
  
• Fraser, A. B., 1978: Why green thunderstorms are severe. Topical Meeting on Meteorological Optics, Keystone, CO, Optical Society of America, MAG-1–MAG-4..
• Gallagher, F. W., III, 1997: Green Thunderstorms. Ph.D. dissertation, University of Oklahoma, Norman, Oklahoma, 248 pp. [Available from UMI, 300 N. Zeeb Rd., Ann Arbor, MI 48106-1346.].
• ——, W. H. Beasley, and C. F. Bohren, 1996: Green thunderstorms observed. Bull. Amer. Meteor. Soc., 77, 2889–2897.
• Kasten, F., and A. T. Young, 1989: Revised optical air mass tables and approximation formula. Appl. Opt., 28, 4735–4738..
• Lynch, D. K., and W. C. Livingston, 1995: Color and Light in Nature. Cambridge University Press, 254 pp..
• McCartney, E. J., 1976: Optics of the Atmosphere: Scattering by Molecules and Particles. John Wiley and Sons, 408 pp..
• Meinel, A., and M. Meinel, 1983: Sunsets, Twilights, and Evening Skies. Cambridge University Press, 163 pp..
• Middleton, W. E. K., 1952: Vision through the Atmosphere. University of Toronto Press, 250 pp..
• Minnaert, M., 1954: The Nature of Light and Color in the Open Air. Dover Publications, 362 pp..
• Nassau, K., 1983: The Physics and Chemistry of Color. John Wiley and Sons, 454 pp..
• van de Hulst, H. C., 1957: Light Scattering by Small Particles. Dover Publications, 470 pp..
• Wyszecki, G., and W. S. Stiles, 1982: Color Science. Concepts and Methods, Quantitative Data and Formulae. 2d ed. John Wiley and Sons, 950 pp..

 

[Stephen Levine]

Once on a jet plane flight throught Ohio, we flew through and above squall lines. At one point, the entire sky outside the plane turned pea green.
Turbulance on the trip was so intense that the stewards never got up from their seats and we seemed to be tossed like a leaf in the wind.

 

[Jason Foster]

I think it certainly is clear that the 'green' tint we see is a filtration and refraction of light through some part of the storm. I always thought it was associated with the hail strictly, not the tornado.

Of course...we all know that those of you have mentioned Allsup's causes greenage.