What makes the clouds pink? When you look at the sky, you mostly see a clear blue sky with white, puffy clouds.
But have you ever glanced up and seen clouds that look pink?
Sometimes, if we are lucky, we will get a peek of clouds in a rainbow of colors, from bluish gray to hot pink.
But how can this be? What makes clouds pink?
Clouds appear pink during sunrise and sunset because of light scattering, atmospheric optics, and refraction, with pollution amplifying colors.
More about How Clouds Form
Clouds are the result of rising and cooling warm, moist air.
Due to the lower atmospheric pressure, the air expands and cools as it rises.
The dew point is the temperature below which water vapor can no longer be held by air.
This is when the vapor begins to condense around dust, pollen, or sea salt particles floating in the atmosphere.
These particles serve as surfaces for water droplets or ice crystals to condense on, earning them the name “cloud condensation nuclei.”
In short, clouds are formed when water vapor condenses into smaller and smaller droplets or ice crystals.
A wide range of meteorological and atmospheric elements influences the formation of various kinds of clouds.
What Makes the Clouds Pink?
Sunlight reflecting off water droplets or ice crystals in clouds is the primary factor in determining cloud color.
The differences in shades are caused by a number of different factors, including:
- The size and density of these particles
- The thickness of the cloud
- The angle at which sunlight penetrates through the atmosphere
But, what makes the sunset clouds pink? Well, there are a number of factors at play.
For instance:
The Role of Atmospheric Optics
Atmospheric optics is the primary culprit in the pinkish hue of some clouds.
The water droplets within a typical white cloud are so tightly packed together that very little light can pass through.
The more cemented these water particles are, the fluffier and denser the cloud.
Water molecules are still present as wispier white clouds, but they are not packed together as densely.
This makes them less blindingly white and allows more light to pass through them.
If we see pink clouds, or even red or orange ones, we can probably credit that color to the sun.
The Role of Refraction
Due to refractions of other colors, sunlight itself turns red at a specific time during dawn and sunset.
Hence, this red light is reflected all over the sky and, when projected through clouds, produces pink, orange, and red tones behind the clouds.
Here, keep in mind that clouds always have the same color. They take on the colorless appearance of the water vapor from which they are formed.
However, the light passing through the clouds causes the rainbow of colors you see.
If you shine a bright pink light behind a white sheet, the sheet itself does not change color; rather, it begins to reflect a new hue.
The Effect of Pollution
Vivid pink clouds may also portend something less favorable, depending on the context, like pollution.
Light is usually blamed when pink clouds appear at sunrise or sunset, but pollution is more likely the cause when the clouds’ colors are extremely vivid and the reds predominate over the pinks.
In fact, experts believe that crimson skies can never occur without atmospheric aerosols.
Human activity, forest fires, and even simple dirt accumulation can emit aerosols into the atmosphere.
Similarly, the high amounts of dust and sandstorm in desert areas like Arizona usually make the clouds in the sky to be a bit more colorful than in other regions.
Fact: Vehicle exhaust is a major source of aerosol pollution in congested urban areas, which are more likely to experience pinker clouds as the day winds down.
The Role of Volcanic Eruptions
Sunsets get very red when forest fires or volcanic eruptions happen.
Volcanic eruptions that discharge large amounts of ash into the atmosphere can cause severe smog.
And this can contribute directly to pollution, which in turn alters the look of clouds.
Similarly, forest fires can produce a nearly black sky due to their ash and smoke.
Air pollution is caused by the burning of fossil fuels, plastics, and aerosol spray cans, which emit toxic chemicals and particles into the atmosphere.
This can again affect the clouds.
An Important Consideration
The most common substances are greenhouse gas emissions, hydrocarbons, sulfuric acid, and trace amounts of metals.
In addition, smog can reduce the intensity of a certain wavelength of light whether it is produced naturally or by humans.
Fact: The color of the sky and the sunset can be altered by the presence of aerosols or haze.
The Effect of the Angle of the Sun
The sun’s angle of incidence through the atmosphere affects the color of clouds.
The sun emits a spectrum of colors, despite its common designation as a source of “white light.”
When sunlight reaches Earth’s atmosphere, all of its individual color wavelengths disperse randomly.
Shorter-wavelength colors like blue and violet scatter earlier. Yet, blue does not disperse as quickly as violet and is therefore more easily visible.
That is also the reason why blue is the predominant color of the sky above us.
During midday, the sun’s rays have a shorter distance to travel through the atmosphere and a steeper angle. That guarantees a preponderance of blue.
When the sun sets, its angle is low, and more of the atmosphere must be traversed by its rays.
This causes the blue, violet, and yellow light to be completely scattered, allowing only the red and orange light to pass through.
Since red has the longest wavelength, it scatters least quickly.
Are Pink Clouds Common?
In some places of the world, pink clouds are frequent, while in others they are extremely uncommon.
Usually, you can spot them around dawn and dusk.
Clouds take on a stronger pink-to-red hue in some parts of the world, especially severely polluted metro regions, due to the high concentration of aerosols in the sky.
Vehicle exhaust, a sandstorm, or forest fires are all examples of sources of aerosols in the environment.
It means that if you live in an area where sandstorms are common or air pollution is high, you can see pink clouds forming above you.
Fact: High pollution makes you more likely to see pink clouds in deserts and heavily populated cities.
What Do Other Colors of the Clouds Suggest?
You can find more colors of clouds besides pink in the sky.
Clouds can vary in color from gray to yellow to red to even pale green during the day, and for a variety of causes.
Blue-Gray and Black Clouds
Blue-gray, gray, or black clouds portend an impending storm.
Clouds that look blue-gray are usually reflecting scattered light from behind them.
As we discussed, blues and grays are on the shorter end of the light wavelength spectrum, thus they tend to be the most prevalent colors we encounter.
Greenish Clouds
There will be times when you notice some gloomier, greener clouds.
Although the exact reason for this green coloration is still a mystery to scientists, it is believed to be the result of red-color sunlight being refracted by storm clouds.
In most cases, a strong thunderstorm will accompany the appearance of greenish clouds.
This usually suggests you are likely to witness heavy downpours.
But, lightning, hail, and even possible tornadoes are all reflected in these clouds.
Yellow Clouds
Yellow clouds are the most common type mentioned when discussing the impact of pollution on cloud formation.
Excess dust in the air, forest fires, or pollution can all cause yellow clouds.
Yellow smoke is common during fires and is directly reflected within the clouds, giving them a yellowish tinge.
Fact: Cities and other regions with high levels of air pollution are generally thought to have a yellowish hue because of the presence of nitrogen dioxide in the air.
Takeaway
What makes the clouds pink?
Many factors, such as the sun’s inclination, air optics, and refraction, might cause this phenomenon.
The sun’s lower angle during these times causes its shorter wavelengths to be scattered, turning the clouds into various shades of red, orange, and pink.
Pollution, volcanic eruptions, and forest fires can all contribute to a more vibrant sky.
Moreover, clouds can appear blue-gray, green, or yellow depending on their composition and the lighting conditions.
