Lightning of Varied Color? Or Not?

I got a question about the color of lightning, that a reader claims to have seen different colors of lightning. Is this guy nuts? No he is not, he is correct. The color of lightning can appear to vary significantly from the bright white color it actually is.

Lightning is very hot (at times can reach temperatures of 54,000 degrees for very brief moments) and hence emits light that appears to the human eye to be nearly white if it is close and in open air away from clouds. However, if lightning is far away and low in the sky, the observer will be looking through a long distance of Earth’s atmosphere at that distant lightning. In a clear atmosphere distant lightning appears yellowish, the farther away the yellower. If the atmosphere is dirty/smoggy, then distant lightning will appear to be more orange in color.

Large hail within a thunderstorm absorbs the longer wavelengths of light leaving the shorter blues and greens to be seen by a ground observer; hence the general rule that if the sky turns greenish in color and it is raining, then expect hail! This greenish sky caused by hail can give a tint to lightning of similar greenish color making it appear greenish in color.

Near sunrise and sunset when the sky can turn colors of orange, pink and red, some of this light can illuminate the lightning bolt and make it appear a similar color to that of the background clouds. Check out the lightning photo I have on my facebook page that clearly shows what appears to be a “pink lightning bolt” only within a few miles of my iPhone camera when I snapped that picture. I have rarely seen lightning appear as vividly pink as in that photo, but it was clearly caused by the color hues from clouds at sunset contaminating the white lightning bolt.

So yes the ground observer can see lightning that “appears” to be many different colors…but the lightning bolt itself is always pretty close to white. The atmosphere, hail, distance, clouds and sunrise/sunset can at times give the bolt the appearance of many different color shades to the ground observer. Some of these color variations can tell you about how close or far the lightning might be; very yellow lightning normally is so far away that the audio thunder from it dissipates before it ever gets to you…so deep yellow lightning is often seen by your eyes, but is silent to the ear. 🙂

 

 

Wavy Undulating Clouds…Dr Steve response

The wavelike appearance to a longer line of normally high clouds are usually in the undulatus cloud family. They are effectively gravity wave clouds with a very similar restoring force to ocean waves.  Pretty specific atmospheric conditions must be met for these types of clouds to form.  Specifically an unstable non-balance between atmospheric stability and the change in the vertical of horizontal wind speed, namely vertical wind shear must be occurring.  The atmospheric stability is related to vertical changes in temperature.  The ratio, of vertical Temperature change  divided by vertical wind speed change can result in the formation of undulatus clouds.  This is called Kelvin-Helmholz instability.  That threshold for undulatus formation from K-H instability is usually fleeting and in small layers of the atmosphere, usually most common at jet flight levels and can be determined and forecast (at least that occurrence might be possible) by vertical wind and temperature measurements from weather ballons.  Undulatus clouds typically do not last more than 20-30 minutes and occasionally you may see one of the waves in the cloud line actually break like an ocean wave…this causes turbulence that you can feel in a jet sometimes…but there are may causes in addition to K-H for jet turbulence.  This link below provides the basics and some photos of undulatus clouds:

http://en.wikipedia.org/wiki/Kelvin–Helmholtz_instability