Sarychev & High Skies

Last updated on September 16, 2023

Sarychev & High Skies: Exploring the Spectacular Effects of Volcanic Aerosols

The mesmerizing phenomenon of atmospheric optics never fails to captivate our attention. While the upper atmosphere has recently dazzled us with stunning displays of noctilucent clouds, the lower stratosphere has also had its fair share of extraordinary events. One such event occurred on June 12, '09 when the Sarychev Peak volcano erupted, injecting fine ash and gaseous sulfur dioxide into the stratosphere. The resulting sulfate aerosol has now formed three distinct layers encircling the Northern Hemisphere at altitudes between 15 - 23km (9 - 15 miles).

Volcanic aerosols have a profound impact on the scattering of sunlight, giving rise to breathtaking sunset and twilight effects. These effects can be both subtle and dramatic, offering a visual feast for sky enthusiasts. While many twilights possess their own natural beauty, those influenced by volcanic activity possess distinct characteristics that set them apart. Here are some key features that are particularly associated with volcanic effects:

1. Bright Yellow Twilight Arch: Following sunset, a vibrant yellow twilight arch often graces the horizon. This radiant display is a hallmark of volcanic activity and serves as a precursor to the other phenomena that follow.

2. Intense Purple Glow: Higher up in the sky, an intense purple glow emerges, casting an ethereal hue over the surroundings. This mesmerizing purple light is a striking manifestation of volcanic aerosols interacting with sunlight.

3. Diffuse Crepuscular Rays and Shadows: As daylight wanes, diffuse crepuscular rays and shadows become more pronounced in volcanic-influenced twilights. These soft, hazy rays and shadows add an element of mystique to the overall ambiance.

4. Fine Structure in Yellow Clouds: With the aid of binoculars or long lens images, one can observe intricate details within the yellow clouds. These fine structures, often visible only in volcanic-influenced twilights, further enhance the visual spectacle.

The eruption of the Kasatochi volcano in the previous year also treated us to these magnificent displays. These volcanic effects continue to astound and inspire sky gazers worldwide.

While the existing content sheds light on the unique atmospheric phenomena resulting from volcanic aerosols, it is important to delve further into the intricacies of these events. Understanding the science behind these captivating displays can deepen our appreciation for the wonders of our atmosphere.

Volcanic aerosols, composed of tiny particles and gases ejected into the stratosphere during an eruption, scatter sunlight in various ways. The scattering of shorter wavelength light (blue and green) is more pronounced than that of longer wavelength light (red and orange). This differential scattering gives rise to the vibrant hues witnessed during volcanic-influenced twilights.

The fine ash particles released into the stratosphere by volcanic eruptions act as nucleation sites for the condensation of water vapor. This process leads to the formation of sulfate aerosols, which can remain suspended in the atmosphere for an extended period. These aerosols effectively scatter sunlight, creating the stunning optical effects we observe.

The precise altitude at which these volcanic aerosols reside determines the extent of their influence on atmospheric optics. The layers of sulfate aerosols resulting from the Sarychev Peak eruption, spanning altitudes between 15 - 23km (9 - 15 miles), have proven particularly impactful. Their dispersion across the Northern Hemisphere has allowed for widespread observation of these awe-inspiring phenomena.

It is worth noting that while volcanic aerosols contribute to remarkable atmospheric optics, they can also have significant climatic implications. The scattering of sunlight by these aerosols can lead to a temporary cooling effect on Earth's surface. By reflecting a portion of incoming solar radiation back into space, volcanic aerosols can influence the planet's energy balance and alter weather patterns.

In conclusion, the Sarychev Peak eruption and its resulting sulfate aerosols have gifted us with a visual extravaganza in the form of stunning sunset and twilight effects. From the vivid yellow twilight arch to the ethereal purple glow and the intricate details within the yellow clouds, each element adds to the captivating allure of these volcanic-influenced twilights. As we continue to explore the mysteries of atmospheric optics, let us revel in the beauty and complexity of our ever-changing skies.

Sarychev Skies - Imaged from Kansas by Doug Zubenel on July 21 and (lowest two images) July 12.

©Doug Zubenel, shown with permission.

While the upper atmosphere at 50 miles altitude has this month seen spectacular noctilucent cloud displays(1,2), the still rarefied air lower down - the stratosphere - has not been entirely uneventful.

On June 12, '09 the Sarychev Peak volcano injected fine ash and gaseous sulfur dioxide into the stratosphere. The resultant sulfate aerosol now encircles the Northern Hemisphere in at least three discrete layers between 15 - 23km (9 - 15 miles) altitude.

Volcanic aerosol scatters sunlight to produces spectacular sunset and twilight effects. 'Ordinary' twilights can be spectacular too and many are labeled volcanic. The following taken together are especially characteristic of volcanic effects:

1. A bright yellow twilight arch shortly after sunset

2. An intense purple glow higher in the sky - the 'purple light'

3. Diffuse (not sharp) crepuscular

rays and shadows

4. Fine structure in the yellow clouds

visible through binoculars or long

lens images.

Last year the eruption of Kasotochi also provided us with these spectacles (1,2,3,4,5,6,7,8,9).

Note: this article has been automatically converted from the old site and may not appear as intended. You can find the original article here.

Reference Atmospheric Optics

If you use any of the definitions, information, or data presented on Atmospheric Optics, please copy the link or reference below to properly credit us as the reference source. Thank you!