The green flash is a rare optical phenomenon that occurs right at sunset or sunrise when a brief flash of green light appears above the sun’s upper rim. This happens due to atmospheric refraction of sunlight and the way different wavelengths of light bend as they pass through Earth’s atmosphere.
The phenomenon requires specific conditions to be visible:
- A clear horizon, typically over water
- Clean, clear air with minimal pollution
- Stable atmospheric conditions
- Unobstructed view of the sunset/sunrise
While it’s called a ‘flash,’ the effect can actually last for a second or two. The best viewing locations are typically beaches or high elevations with clear views of the horizon.