Yellow Means Danger! What Yellow Clouds Really Mean

Aside from looking ominous, yellow clouds can also be a sign of trouble: often, yellow clouds are harbingers of thunderstorms, or, even worse, tornadoes.

Despite the anecdotal evidence, however, scientists are still unsure as to why clouds change color during a thunderstorm. However, there are a few theories:

The Color of the Clouds and Sky

The color of the sky and clouds are completely dependent on the kind of light that they receive. Obviously, our planet’s primary source of light is the sun, which gives off white light. White light appears white because it is a combination of all visible colors in the spectrum. The visible spectrum is all the colors we can perceive with the human eye.

Each of the colors present in the visible spectrum is represented by electromagnetic waves. Colors are dictated by the length of those electromagnetic waves, with short waves coming out as violet, indigo and blue, medium waves coming out as green, yellow and orange, and longer waves showing as red and crimson. Basically, the shorter the wave, the stronger its energy, and the longer the wave, the weaker the energy. This is why blue light can be seen from far away while the red light is very limited in range.

So Why Are Clouds Yellow?

Yellow Clouds
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One school of thought believes that yellow clouds are created by the way air molecules scatter light. Because most storms happen later in the day, the gold-red light from a low sun, combined with the blue of the sky, can create green to yellow clouds that hang ominously in the air.

Meanwhile, another school of thought believes that yellow clouds are created by the clouds themselves: because the water molecules insides of them are intrinsically blue, once they’re hit by the gold-red of sunlight, they turn into greenish or even yellow clouds.

While both ideas are grounded in science, there is one problem: yellow clouds and green skies as precursors for storms are not something that occurs around the planet. Some parts of the world experience yellow clouds and green skies every time a storm hits, while this phenomenon is virtually unheard of in other parts of the world. To understand why we get green skies and yellow clouds, we need to take a closer look at storms themselves.

A Little Bit About Thunderstorms

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In essence, thunderstorms are a way for our planet to release its unspent atmospheric energies. Thunderstorms occur when warm, moisture-rich air meets cold dry air. When this happens, the warm air rises and condenses into water vapors, forming a cloud or a series of clouds. During condensation, the water vapors release a large amount of energy in the form of heat. This is the engine that drives storms into the deadly natural phenomena that it is, and the hotter it is, the more powerful the storm will be once it hits.

But aside from being destructive, storms also have a very important function in the Earth’s electromagnetic ecosystem: it keeps the planet’s electrical balance in check.

See, the surface and atmosphere of the Earth are primed for electrical conduction, thanks to the ground’s negative charge and the atmosphere’s positive charge. Because of this, electrons steadily flow up from the surface to the sky constantly. Storms, particularly thunderstorms, help transfer some of the negative charges back to the surface, sometimes in the form of lightning, but also in the form of solar and ionospheric winds.

Without lightning, or thunderstorms in general, the Earth’s electrical balance would be completely off-kilter. While scientists aren’t exactly sure what would happen if the planet’s electric balance was off, they do concur that it’s probably not going to be good for anyone.

When a thunderstorm becomes extremely powerful, it’s referred to as a supercell. Supercells are basically thunderstorms that have an internal structure so organized, it can sustain a rotating updraft of hot air for several hours, providing the storm with an intense amount of energy to release. This energy is released in the form of whipping winds, enormous hailstones, and sometimes, category-5 tornadoes. Supercells often occur in areas with strong vertical wind shears that create the updraft that powers the thunderstorm.

It’s no secret that severe thunderstorms can have brutal consequences on human populations: constant rain can create flash floods in cities, high winds can overturn ships, and tornadoes can cause untold amounts of death and destruction on a populace, with only the strongest man-made structures withstanding the wrath of a storm.

So Do Yellow Clouds and Green Skies Mean Danger?

Short answer: yes, long answer, well…

As mentioned above, the presence of yellow clouds does not, on their own, mean that a thunderstorm is approaching, neither does a green sky.

However, both are still significant and should be taken with utmost caution. While neither is proof that either a severe thunderstorm or a tornado is on the way, it is still something to worry about. Green or yellow clouds usually occur if the cloud itself is deep enough, which, coincidentally, are the kind of clouds that a thunderstorm has. Green skies, on the other hand, signify that the clouds around it are very, very tall, which, again coincidentally, are the same kind of clouds that tornadoes or hailstorms come from.

Scientists around the world, however, do agree that while a direct connection between green skies and yellow clouds is lacking, there is a strong correlation between the colored sky and severe weather phenomena.

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