‘Glory’ optical phenomenon in Hawke’s Bay: What’s behind the unusual sight?

The 'Glory' optical phenomenon captured by Sharon Matulich at Te Mata Peak. Photo / Sharon Matulich

Walkers on Hawke’s Bay’s Te Mata Peak were treated to a rare sight when a bright halo of light appeared through a cloud of mist and rain.

Curious about the science behind the ‘glory’ and why it’s not your average rainbow, Mitchell Hageman delved into the mystery.

The chances of finding a pot of gold at the end of a glory are slim, but as walker Sharon Matulich found out on Thursday, it makes for a great photo.

Matulich, walking with a friend, snapped the light halo shining through the grass and mist, making it look like a radiant beam was emerging from the ground.

But what causes the strange optical phenomenon that resembles an angel’s halo?

According to Niwa meteorologist and forecaster Seth Carrier, a glory is caused by sunlight or, more rarely, moonlight interacting with the tiny water droplets that comprise mist or clouds.

“The glory consists of one or more concentric, successively dimmer rings, each of which is red on the outside and bluish towards the centre,” Carrier said.

“Due to its appearance, the phenomenon is sometimes mistaken for a circular rainbow, but the latter has a much larger diameter and is caused by different physical processes.”

One or more of the glory’s rings can be visible depending on circumstances, such as the uniformity of droplet size in the clouds. Carrier said rings are rarely complete, often being interrupted by the shadow of the viewer.

“The angular size of the inner and brightest ring is much smaller than that of a rainbow, about 5 to 20 degrees, depending on the size of the droplets.”

He said outdoor glories are commonly observed from aircraft, and when a plane is flying sufficiently low for its shadow to be visible on the clouds, the glory always surrounds it.

When examining the picture from Matulich at Te Mata Peak, Carrier said it’s possible that a phenomenon called “Brocken Spectre” is also visible.

“A Brocken spectre is the magnified (and apparently enormous) shadow of an observer cast in mid-air upon any type of cloud opposite a strong light source,” he said.

“The figure’s head can be surrounded by a bright area called Heiligenschein, or halo-like rings of rainbow-coloured light forming a glory. The “spectre” appears when the sun shines from behind the observer, who is looking down from a ridge or peak into mist or fog.”

Hawke’s Bay has been no stranger to spectacular natural sights of late. Fascinated Kiwis collectively braced the cold last month to try to catch a glimpse or snap a picture of Aurora Australis’ lights sweeping across the country as part of a geomagnetic storm.

Mitchell Hageman joined Hawke’s Bay Today in January 2023. From his Napier base, he writes regularly on social issues, arts and culture, and the community.