Reflected crepuscular rays

Last updated on September 16, 2023

Reflected Crepuscular Rays: A Rare Atmospheric Phenomenon

Crepuscular rays, also known as sunrays, are a captivating atmospheric phenomenon that occurs during sunrise or sunset. These rays of sunlight appear to radiate from the position of the sun, creating a breathtaking display of light and shadow in the sky. However, there is a lesser-known variant of crepuscular rays known as reflected crepuscular rays, which add an extra layer of intrigue to this already fascinating phenomenon.

Reflected crepuscular rays occur when sunlight reflects off a smooth body of water, such as a lake or ocean, and creates an illusion of rays seemingly illuminating the undersides of clouds. While not as commonly observed as their traditional counterparts, reflected crepuscular rays offer a unique and mesmerizing spectacle for those fortunate enough to witness them.

One notable example of reflected crepuscular rays was captured by Brad Peterson on March 21st, 2004, near the L15 freeway in San Diego County, California. The image showcases rays of light apparently emanating from the undersides of clouds, with the possibility that these rays were produced by upward-facing sunrays reflecting off calm water. In this case, there was a large body of water approximately 70 miles to the east, perfectly aligned with the sun's position when the photographs were taken.

The phenomenon of reflected crepuscular rays relies on glancing reflections off smooth water surfaces, which have a strong reflective capacity. While it may initially seem implausible, the physics behind this phenomenon supports its occurrence. As sunlight strikes the calm water surface, it undergoes reflection and refraction, leading to the creation of a mirror-like effect. This effect can redirect the sun's rays upwards towards the undersides of clouds, resulting in the illusion of crepuscular rays.

To fully appreciate the rarity and wonder of reflected crepuscular rays, it is important to understand the conditions necessary for their occurrence. Here are some key points to consider:

1. Smooth Water Surface: Reflected crepuscular rays require a calm and smooth body of water, devoid of significant disturbances such as waves or ripples. This allows for optimal reflection and redirection of sunlight.

2. Sun's Position: The sun must be at a specific angle relative to the observer and the body of water for reflected crepuscular rays to be visible. This alignment is crucial for the sun's rays to reflect off the water surface and reach the undersides of clouds.

3. Cloud Coverage: The presence of clouds is essential for the illusion of rays illuminating their undersides. The interplay between sunlight, clouds, and the reflective properties of the water surface creates a stunning visual display.

4. Atmospheric Conditions: Clear or partially cloudy skies provide the best conditions for observing reflected crepuscular rays. Atmospheric particles, such as dust or pollutants, can scatter or absorb sunlight, diminishing the visibility of the phenomenon.

While reflected crepuscular rays are relatively rare, they serve as a reminder of the captivating and dynamic nature of our atmosphere. These unique displays of light and shadow offer a glimpse into the intricate interplay between sunlight, water, and atmospheric conditions. Witnessing this phenomenon firsthand can leave observers in awe of the beauty and complexity of our natural world.

In conclusion, reflected crepuscular rays are a captivating variant of the traditional crepuscular rays phenomenon. Occurring when sunlight reflects off a calm body of water, these rays create an illusion of illumination on the undersides of clouds. Although relatively rare, witnessing this atmospheric spectacle is a testament to the wonders of nature and the remarkable interplay between light, water, and atmospheric conditions. So, keep your eyes on the horizon during sunrise or sunset, for you never know when you might catch a glimpse of these extraordinary reflected crepuscular rays.

Brad Peterson imaged these rays apparently illuminating the undersides of clouds from the l15 freeway in San Diego County, California near to sunrise on 21st March 2004. It is very possible that these are rare reflected crepuscular rays produced by upward going sunrays reflected up from calm water. There is a large body of water 70 miles to the east that was exactly on the line of sight to the sun when the images were taken. Glancing reflections off smooth water are strong and so this is not as implausible as it sounds. ©2004 Brad Petersen, shown with permission.

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