Known as a "hole punch" cloud, residents in Melbourne, Australia, caught sight of the unique phenomenon as a rainbow splashed across a gaping hole created in the otherwise cloudy sky.
Also referred to as a fallstreak cloud, the cutout is formed after an airplane flies through a cooler, cloudy region and leaves behind a trail of ice crystals.
With a water cloud at a mid-level of about 10,000 feet, the plane flying overhead will leave a condensation trail that produces ice crystals. When the right conditions mix, the ice crystals will grow as they gather moisture from surrounding water droplets.
"The ice crystals eat away at the water droplets," AccuWeather.com Meteorologist Mark Mancuso said.
As ice crystals grow, they become heavier and begin to fall, creating the gaping hole. Mancuso added that it can take hours for the hole to form after an plane moves through.
In Melbourne, the formation was unique as a rainbow brushed through the center of the void, creating a dreamy effect.