<p>You know, there hasn't been <em>too</em> much research into this... but there has been some. For the most part, it's been proven that a green sky most likely means that a <em>thunderstorm</em> is coming. According <a href="http://www.news.wisc.edu/15301">to a researcher</a>:</p>

<blockquote>
  <p>Green is significant, <strong>but not proof that a tornado is on the way</strong>. A
  green cloud “will only occur if the cloud is very deep, which
  generally only occurs in thunderstorm clouds,” Bachmeier says. “Those
  are the kind of storms that may produce hail and tornadoes.” Green
  does indicate that the cloud is extremely tall, and since
  thunderclouds are the tallest clouds, green is <strong>a warning sign</strong> that
  large hail or a tornado may be present.</p>
</blockquote>

<p>In addition, <a href="http://www.scientificamerican.com/article/fact-or-fiction-if-sky-is-green-run-for-cover-tornado-is-coming/">a Scientific American article was run on this</a>:</p>

<blockquote>
  <p>Over the past 15 years, a small group of scientists have weathered the elements working on green thunderstorms as a pet project, publishing a handful of articles in meteorological journals. <strong>All point to the existence of green skies with severe thunderstorms but no direct connection to tornadoes or hail can be made.</strong></p>
</blockquote>

<p>They then go on to state:</p>

<blockquote>
  <p>Threatening green skies during a thunderstorm also proved entirely
  independent of the type of severe weather that came with it. Gallagher
  measured hailstorms where the dominant wavelength of light was green
  as well as hailstorms where it was the typical gray-blue color of
  thunderstorms. <strong>Tornado-producing storms proved similarly divorced from
  any particular sky color, other than dark.</strong></p>
</blockquote>

<p>We do know that green skies are a sign of thunderstorms, though:</p>

<blockquote>
  <p>The moisture particles are so small that they can bend the light and
  alter its appearance to the observer. These water droplets absorb red
  light, making the scattered light appear blue. If this blue scattered
  light is set against an environment heavy in red light—during sunset
  for instance—and a dark gray thunderstorm cloud, the net effect can
  make the sky appear faintly green.</p>
</blockquote>

<p>So to sum all of this up: we know that thunderstorms sometimes create a green sky. However, there is no evidence to prove that a green sky is a sure sign of a tornado or hail. It is however a warning sign, as it shows that a thunderstorm is most likely coming, and it could be a strong storm.</p>

CC BY-SA 3.0
2014-09-08T02:46:56.790Z
Doesn't your whole answer say the exact opposite of *"it shows that a thunderstorm is most likely coming"*? It'd be more correct if you replaced "most" with "more", perhaps, but it still sounds like it might be overstating it (none of the quotes mention any actual probabilities though, so I'm not sure).
naught101
CC BY-SA 3.0
2014-04-16T20:41:08.887Z
2014-04-16T20:41:08.887Z
hichris123
<p>It seems to be a fairly widely held belief that if the sky is green or yellow, a tornado may be developing/approaching. But is there any truth to it? Could the color of the sky actually be associated with the hail that usually accompanies a tornado?</p>

CC BY-SA 3.0
2015-09-11T14:08:40.713Z
It can vary. The belief is held due to the fact that a green cast to the sky indicates heavy hail/rain and the yellow is often due to dust in the air. So, no, not necessarily a sign of a tornado but certainly can be!
L.B.
CC BY-SA 3.0
2014-04-16T11:14:56.187Z
[Apparently not](https://en.wikipedia.org/wiki/Tornado#Myths_and_misconceptions).
naught101
<weather><storms><tornado>
Does a green or yellow sky actually indicate a tornado?
Chris Laplante
# Does a green or yellow sky actually indicate a tornado?

(Asked by: username_0 on 2014-04-16)

It seems to be a fairly widely held belief that if the sky is green or yellow, a tornado may be developing/approaching. But is there any truth to it? Could the color of the sky actually be associated with the hail that usually accompanies a tornado?

**Tags:** weather, storms, tornado

> **Comments:**
> **username_2**: [Apparently not](https://en.wikipedia.org/wiki/Tornado#Myths_and_misconceptions).  
> **username_1**: It can vary. The belief is held due to the fact that a green cast to the sky indicates heavy hail/rain and the yellow is often due to dust in the air. So, no, not necessarily a sign of a tornado but certainly can be!  

---

## 1 answers

### Answer by username_3 on 2014-04-16. Score: 11 | Accepted answer

You know, there hasn't been *too* much research into this... but there has been some. For the most part, it's been proven that a green sky most likely means that a *thunderstorm* is coming. According [to a researcher](http://www.news.wisc.edu/15301):

> Green is significant, **but not proof that a tornado is on the way**. A
> green cloud “will only occur if the cloud is very deep, which
> generally only occurs in thunderstorm clouds,” Bachmeier says. “Those
> are the kind of storms that may produce hail and tornadoes.” Green
> does indicate that the cloud is extremely tall, and since
> thunderclouds are the tallest clouds, green is **a warning sign** that
> large hail or a tornado may be present.

In addition, [a Scientific American article was run on this](http://www.scientificamerican.com/article/fact-or-fiction-if-sky-is-green-run-for-cover-tornado-is-coming/):

> Over the past 15 years, a small group of scientists have weathered the elements working on green thunderstorms as a pet project, publishing a handful of articles in meteorological journals. **All point to the existence of green skies with severe thunderstorms but no direct connection to tornadoes or hail can be made.**

They then go on to state:

> Threatening green skies during a thunderstorm also proved entirely
> independent of the type of severe weather that came with it. Gallagher
> measured hailstorms where the dominant wavelength of light was green
> as well as hailstorms where it was the typical gray-blue color of
> thunderstorms. **Tornado-producing storms proved similarly divorced from
> any particular sky color, other than dark.**

We do know that green skies are a sign of thunderstorms, though:

> The moisture particles are so small that they can bend the light and
> alter its appearance to the observer. These water droplets absorb red
> light, making the scattered light appear blue. If this blue scattered
> light is set against an environment heavy in red light—during sunset
> for instance—and a dark gray thunderstorm cloud, the net effect can
> make the sky appear faintly green.

So to sum all of this up: we know that thunderstorms sometimes create a green sky. However, there is no evidence to prove that a green sky is a sure sign of a tornado or hail. It is however a warning sign, as it shows that a thunderstorm is most likely coming, and it could be a strong storm.

> **Comments:**
> **username_2**: Doesn't your whole answer say the exact opposite of *"it shows that a thunderstorm is most likely coming"*? It'd be more correct if you replaced "most" with "more", perhaps, but it still sounds like it might be overstating it (none of the quotes mention any actual probabilities though, so I'm not sure).  

---

