Why Are There Pink Clouds In The Sky?

Whenever we look at the clouds, we usually see blue and white clouds in the sky. Sometimes, we see different cloud colors like yellow and orange. Especially during sunrise or sunset. But how many times in your life have you ever seen pink clouds?

This article explores how clouds are formed and some types of clouds that appear in the sky. It also examines the causes of pink clouds in the sky. 

Related Read: Mammatus Clouds, How Is Rain Formed?

How are clouds formed? 

Water from Earth's bodies rises into the atmosphere through evaporation, transforming into unseen water vapor. This vapor then rises as part of the atmospheric circulation and, in the process, experiences cooling due to reduced pressure in higher altitudes. The cooled vapor then results in the formation of visible clouds.

As the air cools down, water vapor takes on a solid form and forms a cloud. However, water vapor can't form a cloud with a surface particle to condense. Science refers to these particles as condensation nuclei. These particles could be dust or pollen. They attract water molecules because they are hygroscopic.

Clouds typically form when the concentration of water vapors in the atmosphere exceeds the capacity of the air to hold it². An example of this occurs when evaporation processes inject substantial amounts of water vapor into the surrounding air. Notably, when the atmospheric capacity for water vapor has been saturated, it forms clouds.

When is the point where the atmosphere can't hold water vapors anymore?

The atmosphere doesn't hold water when the temperature drops. It only contains water when the temperature is high. So, the warmer the temperature, the more water it'll keep.

Clouds also form when air is forcefully pushed upwards in areas with low pressure. They start at a wide range of high or low altitudes towards the ground.  

What causes pink clouds? 

F.A.R. Russell gave a splendid description of a beautiful evening sunset. At around 4:18 p.m., the sky was nearly clear. There were a few cirrocumulus clouds in the sky, and she slowly watched them turn pink. Immediately after sunset, they turned a deep shade of red¹. 

Again, at 4:35 p.m., she saw the clouds turn into a delicate shade of pink. Some cirrus-like clouds were stretched across the clouds. The defined borders of the pink cloud contrasted with the deep blue sky. The pink clouds became brighter as the sun set and the darkness increased. It cast a weird light over the horizon at 5 p.m. For the next 58 minutes, the brightness of the pink clouds fluctuated until they finally dispersed. 

At some point in our daily lives, we have experienced pink clouds at sunset or sunrise. Have you ever wondered about the phenomenon that causes the colors of the sky to change to pink at a particular time of the day? 

The color of the sky changes because of the color of the light it receives. The sun produces white light, which reflects off molecules and small particles in the atmosphere. The process of light reflecting on atmospheric molecules is known as scattering. The light scatters across different light wavelengths: red, blue, orange, yellow, indigo, and green. 

However, the longer light travels through the sky, the fewer colors we see. Sometimes, the red part of the light wave spectrum mixes with the white rays of sunlight to form pink clouds. It also occurs when there are a lot of fine particles in the atmosphere. 

Major Types of Clouds 

There are three classifications of clouds based on their altitude. They are: 

• High clouds
• Mid-level clouds
• Low-level clouds

High-level clouds 

There are three classifications of clouds based on their altitude. They are: 

• High clouds
• Mid-level clouds
• Low-level clouds

High-level clouds 

High-level clouds are clouds that are above 20,000 ft. The type of high clouds usually has the prefix 'cirro' attached to it. The three main types of high clouds are cirrus, cirrostratus, and cirrocumulus. 

Cirrus clouds usually occur between 20,000 ft to 40,000 ft. They are short, wispy, and detached clouds that only form at high altitudes. Cirrus clouds produce precipitation, but they never reach Earth. Instead, it forms a variant cloud known as virga clouds. There are five different subtypes of cirrus clouds, namely: 

• Cirrus fibratus
• Cirrus uncinus
• Cirrus spissatus 
• Cirrus floccus
• Cirrus castellanus.

Cirrostratus clouds form at the same level as cirrus clouds, above 20,000 ft. Cirrostratus clouds are transparent, and they cover extensive areas of the sky. Sunlight or moonlight reflects through the thin sheets, causing a halo. Cirrostratus clouds form through airplane vapors left in the dry upper troposphere. The two cirrostratus cloud subtypes are: 

• Cirrostratus fibratus
• Cirrostratus nebulosus. 

Last, cirrocumulus clouds are small layers of white clouds called cloudlets. The cloudlets, formed from ice crystals and super cool water, are usually grouped at high altitudes. They typically look like ripples in the air.

Cirrocumulus clouds produce precipitation like cirrus clouds but never reach the group. There are four subtypes of cirrocumulus clouds:

• Cirrocumulus stratiformis
• Cirrocumulus lenticularis
• Cirrocumulus floccus 
• Cirrocumulus castellanus. 

Mid-level clouds 

Mid-level clouds occur at altitude levels between 6,500 ft and 20,000 ft. The mid-level clouds have the prefix 'alto' attached to them. Mid-level clouds are altocumulus and altostratus clouds.

Altocumulus occurs in the sky at 7,000 to 18,000 ft. They are small mid-level patches of clouds. The cloudlets always appear in round clumps. However, it can occur in various shapes because of different altocumulus clouds.

They form through the altostratus breakup or atmospheric wave production by mountainous terrains. The subtypes of altocumulus clouds are the altocumulus stratiformis, altocumulus lenticularis, altocumulus castellanus, and altocumulus floccus clouds.

Altostratus clouds form at 6,500 ft to 20,000 ft. They are layered, thin sheets of clouds that form from water vapors and ice crystals. Altostratus spread over extensive areas of the sky.

They usually form when a layer of cirrostratus drops from a higher level. The layers of altostratus clouds often include optical effects like coronas and iridescence. Whenever there are altostratus clouds, the sun can't cast shadows.

Low clouds

Low-level clouds are clouds that occur at the lowest level of the atmosphere. They appear below 6,500 ft. Low-level clouds are nimbostratus and stratocumulus clouds. 

Nimbostratus clouds occur between 2,000 ft and 10,000 ft. They are dark gray clouds that arise in thick layers. Nimbostratus clouds block the sun and produce rain. It forms when altostratus clouds thicken. You can associate nimbostratus clouds with persistent and moderate rainfall or snowfall.

Stratocumulus clouds appear at 1,500 ft to 6,500 ft. They are low-level patches of clouds with well-defined bases. Their colors often vary from dark gray to bright white. Stratocumulus clouds indicate a change in weather. The four subtypes of stratocumulus clouds are: 

• Stratocumulus stratiformis
• Stratocumulus cumulogenitus
• Stratocumulus castellanus
• Stratocumulus lenticularis.

Rayleigh Scattering 

Rayleigh scattering happens when the light's wavelength hits smaller particles. The Rayleigh scattering of light causes the charged particles to move back and forth³. However, colors on the shorter wavelength reach the human eyes first. These colors are blue and violet. This explains why the sky is primarily blue during the daytime.

This phenomenon also explains the colors we see during sunrise and sunset. Sunset passes through expansive sky area, increasing the scattering distance of light waves. The colors on the shorter wavelengths are scattered more, leading to a warm, reddish color.

Conclusion: Pink Clouds

Clouds form in every part of the world. However, the frequency at which we see different cloud colors varies. Seeing differently colored clouds different from blue and white also depends on the angle at which the sun's rays hit the atmosphere. 

You can catch pink clouds during an early sunrise and sunset. The pink hue is hard to miss at any time and anywhere.