Rare green glow phenomenon captured in Hong Kong’s sunset


25th November 2023 – (Hong Kong) Hong Kong witnessed a mesmerising event as the setting sun adorned the sky with a rare green glow, captivating both photographers and netizens alike. The Hong Kong Observatory, intrigued by the phenomenon, shared an explanation accompanied by captivating photos that showcased the fleeting green glow.

Photographers were fortunate enough to capture the green flash phenomenon, which lasted only one or two seconds, on 19th November near the airport. The Hong Kong Observatory, referencing the photos, shed light on the rarity of this occurrence. The green flash was described as a momentary burst of green light appearing above the setting sun.

The Observatory took to Facebook with a post titled “A Touch of Green Above the Sun?” and asked, “Did you notice a hint of green at the very top of the sun? This Sunday evening (19th November) our friends from the ‘Community Weather Observation Scheme’ (CWOS) captured an incredibly rare green glow! Have you seen that tiny green spot at the top of the sun? It usually occurs during sunrise or sunset and typically lasts for only one or two seconds!”

The Observatory went on to explain the complex mechanism behind the green flash phenomenon. One possibility is that the sun’s light, as it approaches the horizon near sea level, passes through a temperature inversion layer in the atmosphere, causing refraction. Different colours of light have varying refractive indices, with blue and green light refracting more than other colours. Since blue light is mostly scattered by the air, what remains visible is the green flash.

Photographers and netizens were amazed by the phenomenon, and comments flooded in praising the lucky captures. One photographer commented on the Observatory’s Facebook post, expressing gratitude for witnessing and sharing such a unique event. Netizens were quick to applaud, with comments such as, “Incredible! You managed to capture that fleeting moment in just one or two seconds,” and “Impressive! You even captured the knowledge within that split second, impressive!”

Some individuals analysed the circumstances surrounding capturing the green glow in Hong Kong. They noted that due to long-term atmospheric pollution, capturing a small hint of green on the sunset’s edge might not be too difficult. However, achieving a large or complete green layer effect near the horizon is exceedingly challenging. In a lighthearted manner, one netizen compared the green flash above the setting sun to the metaphorical concept of the sun wearing a green hat.

On the same evening of 19th November, other fortunate netizens managed to photograph the green flash phenomenon in Siu Lam. Overwhelmed with joy, one netizen posted, “I didn’t even know I captured the green glow until I saw the Observatory’s post. But I did capture the sunset that day, so I should have captured it too.” Such a stroke of luck prompted netizens to shower the post with comments of awe and admiration, using words like “amazing” to express their astonishment.