The sky can take on various colors depending on the weather conditions, and we’ve all taken the time to take in the beauty of the sky in yellow, grey, blue, red, purple, and many variations in between. However, apart from enjoying the aesthetics, you may wonder why the sky presents certain colors. Have you ever looked out the window and wondered, “Why is the sky yellow?”
The colors of the sky can impact our mood and point to weather conditions ahead. Here, we explain what a yellow sky means and why it happens.
The sky may turn yellow at sunset due to a high presence of dust in the environment or because of a brewing storm.
A coming storm is one of the most common causes of a yellow sky, and a yellowish, orange hue might indicate a winter storm brewing on a relatively warm day. When you first notice a yellow-orange tone in the sky, it can create an eerie atmosphere or simply be a cause for fascination. Regardless, this yellow-orange look differs from the blue light we’re used to.
According to the National Severe Storms Laboratory, most thunderstorms occur in the late afternoon. They can also form during the early evening as the storm requires heat from the day to form. Notably, many of them spring up during the summer and spring months.
Although you may notice that particular clouds block the sunlight during this period, sunsets still emit colors as the light filters through. On warm days, shorter wavelengths of blue light are scattered quickly, leaving the sky with vivid colors on the yellow-orange-red end of the spectrum. As a result, the same process that initiates brilliant colors at sunset makes the sky turn orange or yellow when a storm is brewing.
In some cases, a storm brewing can turn the sky green. Depending on the area, when the sky appears yellow, it might serve as a sign of a tornado or hurricane. Since thunderstorms usually occur during warmer periods like the late afternoon, the hue can indicate you need to prepare for the storm ahead. The visible glowy atmospheric effect presents an eerie-looking yet stunning background.
Related read: Storm Quotes.
You might be wondering what determines the colors of the sky at certain periods, like when the sun is setting or rising.
The shades of the sun when the sun is setting result from something called scattering. Little particles and molecules present in the Earth's atmosphere steer the direction of light rays. This occurrence causes light to scatter in the atmosphere. As a result, this scattering effect leads to the colors we observe at particular points of the day.
The specific details, however, come about due to particular light wavelengths and varying sizes of atmospheric particles. On a regular day, molecules in the air tend to scatter violet and blue wavelengths more than other colors. This explains why you’ll notice bright blues on a clear day.
You’ll notice that the sun is low on the horizon during sunset. As a result, the sunlight rays pass through more air than when the sun is high in the sky. Since the light passes through more air during this period, more particles exist to scatter this light. This phenomenon scatters more blues out of sight, resulting in yellow light to the human eye.
Another unusual sign that brings about the yellow tint is the presence of dust particles, water droplets, and moisture. This could also cause a reddish and dark-looking tone.
An event occurred in the UK in 2017 when residents noticed a reddish sun and a dark yellow sky. This phenomenon was attributed to a powerful system pulling up dust particles in the sky.
The University of Nottingham found that the dust had come all the way from the Sahara, after passing through the African continent before making its way to Europe due to Storm Ophelia. People residing in parts of England, including the southwest and midlands, noticed this change.
Apart from dust storms, moisture also contributes to changes in the hue. The red hue has the longest wavelength in the color spectrum. Since shorter ones like blues scatter and break up aren’t as visible as red, in such instances, we see such warm colors as an indication of high dust and moisture. Depending on the amount of dust, you may also notice an orange hue.
The sky can show up as a yellow hue for varying reasons. Some of these include an abundance of dust and a storm coming. Apart from these scenarios, you might also notice that the day's tone becomes a deep yellow or orange during sunsets.
As the sky takes on different hues, it continues to serve as a striking background as we go about our lives. These hues result from the wavelengths of light. You can usually find a scientific explanation for why it takes on a particular shade. This not only helps you ease your mind but can also help you prepare where necessary.
Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.
Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.