Sundogs, Sun Dogs, Parhelia, Mock Suns

Last updated on September 16, 2023

Sundogs, Sun Dogs, Parhelia, Mock Suns: A Detailed Exploration

Sundogs, also known as Sun Dogs, Parhelia, or Mock Suns, are a fascinating atmospheric optical phenomenon that frequently occurs alongside the 22º halo. These captivating celestial displays are most commonly observed when the sun is positioned low in the sky. To locate sundogs, simply extend your arm and look approximately 22° to the left and right of the sun, at the same height. When the sun is higher in the sky, the sundogs appear further away.

Each sundog is characterized by a vibrant red coloration towards the sun, often accompanied by shades of green and blue extending beyond. The intensity of sundogs can vary greatly, ranging from blindingly bright manifestations to subtle, smudged hues adorning the sky. Interestingly, these mesmerizing optical phenomena can be observed worldwide, regardless of the ground level temperature or time of year. In Europe and North America, one can expect to witness a sundog approximately twice a week if actively sought out.

The Formation of Sundogs

Sundogs form as a result of sunlight interacting with ice crystals suspended in the Earth's atmosphere. These tiny ice crystals act as prisms, bending and refracting sunlight to create the stunning visual effect of sundogs. The precise shape and orientation of the ice crystals play a crucial role in determining the appearance of sundogs.

When sunlight enters the ice crystal at a specific angle, it undergoes internal reflection within the crystal and emerges at an angle of 22°. This angle corresponds to the distance at which sundogs are observed from the sun. The process of refraction within the ice crystals causes the separation of sunlight into its constituent colors, resulting in the characteristic red hues towards the sun and the additional greens and blues that can be seen beyond.

Solar Altitude and Sundogs

The altitude of the sun in the sky significantly influences the visibility and positioning of sundogs. As mentioned earlier, sundogs are most easily observed when the sun is low on the horizon. When the sun is higher, the sundogs appear farther away from the sun. This change in position occurs due to the varying angles at which sunlight interacts with the ice crystals in the atmosphere. Therefore, the altitude of the sun plays a crucial role in determining the appearance and proximity of sundogs.

Sundogs and Moon Dogs

While sundogs are commonly associated with the sun, similar optical phenomena can also occur in relation to the moon. These lunar counterparts, known as moon dogs or paraselenae, exhibit similar characteristics to sundogs but are visible when the moon is low on the horizon. The formation of moon dogs follows a comparable process to that of sundogs, with moonlight interacting with ice crystals to create the captivating visual spectacle.

Sundog Image Gallery

To truly appreciate the breathtaking beauty of sundogs, one can explore an image gallery showcasing these atmospheric optical phenomena. These photographs capture the vivid colors and intricate patterns exhibited by sundogs, offering a glimpse into the awe-inspiring wonders of our atmosphere. Each image serves as a testament to the diversity and splendor of sundogs found across different locations and at various times of the year.

Conclusion

Sundogs, Sun Dogs, Parhelia, or Mock Suns are captivating atmospheric optical phenomena that never fail to inspire wonder and curiosity. These ethereal displays, often accompanied by the 22º halo, showcase nature's ability to create breathtaking spectacles in the sky. Whether observing them as vibrant bursts of red flanking the sun or as delicate smudges of color on the horizon, sundogs remind us of the beauty and complexity of our natural world. So, next time you find yourself under a clear sky with a low sun, take a moment to search for these elusive celestial companions and marvel at the magic they bring to the heavens above.

Red hued sundogs flank the sun's left and right. Wide angle image by Mark Trusz ( Photography site, Flikr) from Toronto Islands, Canada. The circular halo is the 22° halo. Image ©Mark Trusz , shown with permission.

Sundogs, sometimes called Sun Dogs, Parhelia or Mock Suns, are with the 22º halo, the most frequent of the ice halos. They are most easily seen when the sun is low. Look about 22° (outstretched hand at arm's length) to its left and right and at the same height. When the sun is higher they are further away. Each 'dog' is red coloured towards the sun and sometimes has greens and blues beyond. Sundogs can be blindingly bright, at other times they are a mere coloured smudge on the sky. They are visible all over the world and at any time of year regardless of the ground level temperature. In Europe and North America one will be seen on average twice a week if searched for.

How they form. Solar Altitude. Moon Dogs. Image gallery.

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Reference Atmospheric Optics

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