Sundog Colours

Last updated on September 16, 2023

Sundog Colors: A Closer Look at Nature's Spectacle

Have you ever witnessed the breathtaking beauty of sundogs? These dazzling optical phenomena, also known as parhelia, occur when sunlight passes through ice crystals in the atmosphere. While the existing content provides a glimpse into the mesmerizing colors of sundogs, let's delve deeper and explore the intricate details of these celestial displays.

The Kaleidoscope of Sundog Colors

Sundogs exhibit a stunning array of hues, with each sundog showcasing its own unique palette. When observed up close, the sunward edge of a sundog reveals a captivating progression of colors. Starting from a warm tawny red, the colors transition through vibrant shades of orange, straw yellow, and smoky yellow. As we move further, pastel greens emerge, followed by a subtle hint of blue. It's a true spectacle for the eyes, reminiscent of an artist's brush strokes across the sky.

The Science Behind Sundog Colors

To understand the science behind sundog colors, we need to delve into the behavior of plate crystals that form these celestial phenomena. These crystals rotate about near-vertical axes, resulting in varying angles of incidence and skew when they interact with sunlight. As a result, the impinging rays of the sun hit each crystal at different angles, leading to color overlap and mixing. This phenomenon becomes more pronounced as we move from the red end of the spectrum towards the blues. The resulting kaleidoscope of colors adds to the enchantment of sundogs.

Unveiling the Halo Connection

Did you know that the colors seen in 22° halos are similarly mixed? Just like sundogs, these atmospheric halos are formed by the interaction of sunlight with ice crystals. The intricate dance between light and crystal orientation gives rise to a blend of colors within these halos. However, it is important to note that the colors observed in circumzenithal and circumhorizon arcs, which are also atmospheric optical phenomena, remain distinct and unaffected by color mixing.

Exploring the Absence of Pure Spectrum Colors

One fascinating aspect of sundog colors is the absence of pure spectrum colors. Unlike a rainbow, which displays distinct bands of colors, sundogs exhibit a continuous blend of hues. This lack of purity is a result of the complex interplay between sunlight and the rotation of ice crystals. While it may seem counterintuitive at first, this absence of pure colors adds to the allure and mystique of sundogs, making them a truly unique natural spectacle.

The Individuality of Sundogs

Every sundog possesses its own distinct set of colors, making each sighting a one-of-a-kind experience. The interplay between atmospheric conditions, ice crystal properties, and the observer's position creates a tapestry of colors that is never replicated. This individuality adds an element of surprise and wonder to each encounter with these celestial phenomena, making them even more captivating.

Beyond the Colors: Other Aspects of Sundogs

While the focus thus far has been on the colors of sundogs, it's important to note that they are often accompanied by other atmospheric optical phenomena. These can include 22° halos, circumzenithal arcs, and circumhorizon arcs. The combination of these phenomena in the sky creates a breathtaking panorama that leaves spectators in awe. Observing these celestial displays not only offers a visual feast but also provides valuable insights into the intricate workings of light and atmospheric conditions.

In conclusion, sundogs are a sight to behold, showcasing a mesmerizing palette of colors that captivate observers worldwide. The absence of pure spectrum colors, the mixing of hues within sundogs and halos, and the individuality of each sundog sighting all contribute to the allure and mystique of these natural wonders. So, keep your eyes to the sky and embrace the burst of colors that sundogs bring, for they are a reminder of the beauty and complexity that nature has to offer.

Sundog Close-up imaged by Mitsy Marx (images). The sun is to the right.

©Mitsy Krzywicki, shown with permission.

This close-up shows sundog colours well, although each sundog is differs slightly in its own way. The sunward edge is a tawny red progressing through orange, straws and smoky yellows to pastel greens and then a hint of blue.

There are no pure spectrum colours. Plate crystals forming the 'dog' are in all rotational positions about near vertical axes. The sun's rays therefore impinge on each crystal at different angles of incidence and skew causing some colour overlap that increases from red towards the blues. 22° halo colours are similarly mixed. Circumzenithal and circumhorizon arc colours are not.

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Reference Atmospheric Optics

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