OPOD - Stacked Blue Moons

OPOD - Stacked Blue Moons: A Phenomenon of Atmospheric Optics

Have you ever witnessed the mesmerizing sight of stacked "Blue Moons"? On August 31st, 2012, in Argentina, photographer Luis Argerich captured the breathtaking spectacle of at least three stacked "Blue Moons" rising and descending over the Rio de la Plata. These extraordinary images provide a glimpse into the fascinating world of atmospheric optics, where the interplay of light and atmospheric conditions creates stunning visual phenomena.

The Enigmatic Blue Moons

While the term "Blue Moon" is commonly associated with a rare occurrence of two full moons in a single calendar month, real blue moons that exhibit a blue or indigo hue are exceedingly rare. True blue moons arise when moonlight interacts with particles in the atmosphere, such as smoke and droplets from forest fires, volcanic ash, or other particles. These particles, known as Mie scatterers, selectively scatter long wavelengths, giving rise to the elusive blue coloration of the moon. However, these celestial events are infrequent and require specific atmospheric conditions to manifest their ethereal beauty.

The Mirage of Stacked Moons

The phenomenon of stacked or pancake moons and suns is a result of mirages – optical illusions that create miraged slices of the lunar or solar disk. Temperature inversion layers play a crucial role in the formation of these mirages. These layers occur when a vertical temperature profile exhibits an abnormal increase in temperature with height, causing warmer air to overlay cooler air.

In the simplest case of a single inversion layer, moon rays passing through the layers of different temperatures are refracted and deflected, resulting in three image slices. Two of these slices appear erect and rise at moonrise, while the third slice is inverted and descends. However, as with most atmospheric phenomena, the reality is often more complex and captivating than this simplified explanation.

The Complexity of Luis's Mirage

Luis Argerich's mirage of stacked "Blue Moons" presents a more intricate scenario. The images reveal the Moon's shape continuously changing as its rays traverse the diverse temperature layers within the atmosphere. The uppermost domed mirage showcases the Mare Crisium near the Moon's upper limb, while the Mare Tranquillitatis drapes over the mirage's lip. This intricate interplay between the Moon, light, and the varying atmospheric temperatures creates a captivating visual spectacle.

Appreciating Atmospheric Optics

Atmospheric optics offers a wealth of stunning visual phenomena that continually captivate and inspire us. By understanding the underlying principles of how light interacts with the atmosphere, we gain insight into the mechanics behind these breathtaking events. From the rare occurrence of true blue moons to the mirages that create stacked celestial bodies, each phenomenon showcases the dynamic nature of our atmosphere and its impact on our perception of the world above.

Exploring Further

If you're intrigued by atmospheric optics and want to delve deeper into this captivating field, there are numerous resources available to expand your knowledge. Books such as "Atmospheric Optics" by Walter Tape and "Light and Color in the Outdoors" by Marcel Minnaert provide comprehensive insights into the science behind these captivating phenomena. Additionally, websites like Atmospheric Optics (atoptics.co.uk) offer a wealth of information, images, and discussions about atmospheric optics and related topics.

Conclusion

The enchanting sight of stacked "Blue Moons" captured by Luis Argerich serves as a reminder of the wonders that lie above us. Atmospheric optics, with its interplay of light and atmospheric conditions, continually surprises us with its captivating displays. From the rarity of true blue moons to the intricate mirages that create stacked celestial bodies, each phenomenon adds to our appreciation of the dynamic nature of our atmosphere. So, keep your eyes on the sky and be ready to witness the extraordinary beauty that atmospheric optics has to offer.

Stacked 'Blue' Moons

At least three stacked "Blue Moons" rising and descending over the Rio de la Plata, Argentina on 31st August '12. Images by Luis Argerich.

In the large image we see Mare Crisium near the upper limb and Mare Tranquillitatis draped over the lip of the uppermost domed mirage. The Moon's shape constantly changed as its rays differently traversed the many temperatured atmospheric layers.

Images ©Luis Argerich

Blue Moons:

Real blue moons are exceeding rare - "as rare as a blue moon". They occur when moonlight is filtered by smoke and droplets from forest fires, volcanic ash and other particles. When the particles are in a special size range of .5 - 2 micron (Mie scatterers) they can sometimes (but rarely) selectively scatter long wavelengths to leave the moon and sun a blue or indigo colour.

Then there are the purely calendrical blue moons when there are two quite ordinary full moons in a calendar month.

Stacked Moons:

Stacked or pancake moons and suns are miraged images - miraged slices of the lunar or solar disk.

Temperature inversion layers - a kinked vertical temperature profile where abnormally warmer air overlays cooler.

Moon rays are refracted and deflected as they pass between the layers of different temperature. In the simplest and purest case of a single inversion layer there can be three image slices. Two slices are erect and rise at moonrise. The third image slice is inverted and descends.

Luis's mirage is more complicated - They usually are!

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Reference Atmospheric Optics

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  • "OPOD - Stacked Blue Moons". Atmospheric Optics. Accessed on March 29, 2024. https://atoptics.co.uk/blog/opod-stacked-blue-moons/.

  • "OPOD - Stacked Blue Moons". Atmospheric Optics, https://atoptics.co.uk/blog/opod-stacked-blue-moons/. Accessed 29 March, 2024

  • OPOD - Stacked Blue Moons. Atmospheric Optics. Retrieved from https://atoptics.co.uk/blog/opod-stacked-blue-moons/.