Sun pillar

Sun Pillar: A Spectacular Atmospheric Phenomenon

Have you ever witnessed a stunning display of light shooting up from the horizon during sunrise or sunset? If so, you may have observed a remarkable atmospheric optical phenomenon known as a sun pillar. These captivating vertical columns of light can be seen when sunlight reflects off the surfaces of ice crystals in the atmosphere. In this article, we will delve deeper into the science behind sun pillars and explore the various factors that contribute to their formation.

The Science Behind Sun Pillars

Sun pillars are an optical phenomenon that occurs when sunlight interacts with ice crystals suspended in the atmosphere. These ice crystals can be found in high-altitude clouds, such as cirrus clouds, or in the presence of ice fog or freezing rain. When sunlight passes through these ice crystals, it undergoes a process called refraction, where the light is bent or deflected as it changes medium. This refraction causes the light to disperse into its constituent colors, creating a beautiful display of colors in the sky.

Formation and Appearance

When sunlight passes through flat, plate-like ice crystals, it can produce a vertical beam of light extending upwards or downwards from the position of the sun. This beam of light appears as a pillar, which can range in color from white to vibrant hues such as red, orange, and pink. The length and brightness of the sun pillar depend on several factors, including the size and shape of the ice crystals, as well as the angle at which the sunlight interacts with them.

Factors Influencing Sun Pillar Appearance

Several factors contribute to the appearance and intensity of sun pillars. Let's take a closer look at these factors:

  1. Ice Crystal Shape: The shape of ice crystals plays a crucial role in determining the appearance of sun pillars. Flat, plate-like crystals tend to produce more prominent and elongated pillars, while columnar or needle-shaped crystals may result in shorter and less defined pillars.

  2. Sun's Altitude: The altitude of the sun above the horizon affects the length and visibility of the sun pillar. Sun pillars are more likely to be observed when the sun is low on the horizon, such as during sunrise or sunset, as the light has a longer path through the atmosphere and encounters more ice crystals.

  3. Ice Crystal Orientation: The orientation of ice crystals also influences the appearance of sun pillars. When the crystals align horizontally, the resulting pillar is more distinct and vertical. Conversely, randomly oriented crystals may produce a diffuse and less defined pillar.

  4. Atmospheric Conditions: The presence of high-altitude clouds, ice fog, or freezing rain is necessary for the formation of sun pillars. These atmospheric conditions provide the necessary ice crystals for sunlight to interact with and create the pillar effect.

Variations of Sun Pillars

While sun pillars are commonly observed as vertical columns of light, variations of this phenomenon can occur under specific circumstances. Some notable variations include:

  • False Sun Pillars: False sun pillars are caused by light reflecting off horizontally oriented ice crystals, such as those found in cirrostratus clouds. These pillars can appear as horizontal bands of light above or below the sun, creating a mesmerizing spectacle.

  • Multiple Pillars: In certain cases, more than one sun pillar can be observed simultaneously. This occurs when sunlight interacts with multiple sets of ice crystals at different altitudes or orientations, resulting in multiple vertical beams of light.

Capturing the Beauty of Sun Pillars

If you're fortunate enough to witness a sun pillar, capturing its beauty through photography can be a rewarding experience. To photograph a sun pillar, consider the following tips:

  • Use a tripod to ensure stability and reduce camera shake.
  • Adjust your camera settings to capture the vibrant colors and details of the pillar.
  • Experiment with different angles and compositions to capture the best shot.
  • Consider including elements such as trees, buildings, or landscapes to provide context and enhance the visual appeal of the photograph.

Conclusion

Sun pillars are awe-inspiring atmospheric optical phenomena that add a touch of magic to our skies. Understanding the science behind their formation and the factors influencing their appearance allows us to appreciate these natural wonders even more. So, keep your eyes to the sky during sunrise or sunset, and you may be fortunate enough to witness the mesmerizing beauty of a sun pillar.

Sunset at Etton, North Yorkshire.

Photographed by Trevor Appleton at 19.35 UTC on 8th May '01 when the sun was 1° above the horizon.

Image ©Trevor Appleton, reproduced with permission.

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Reference Atmospheric Optics

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  • "Sun pillar". Atmospheric Optics. Accessed on March 28, 2024. https://atoptics.co.uk/blog/sun-pillar-3/.

  • "Sun pillar". Atmospheric Optics, https://atoptics.co.uk/blog/sun-pillar-3/. Accessed 28 March, 2024

  • Sun pillar. Atmospheric Optics. Retrieved from https://atoptics.co.uk/blog/sun-pillar-3/.