Fallstreak Hole — The Gate of Paradise in the clouds of Victoria's east, Australia

I never saw the gates of paradise but may be its seem like these unusual clouds, amazing and strange hole in the sky. In the most common hypothesis states that the hole in the clouds caused by falling ice crystals. The ice crystals may form in the higher clouds or exhaust overflying aircraft. 

Fallstreak Hole — The Gate of Paradise in the clouds of Victoria's east, Australia

If the air has a suitable temperature and humidity, the falling crystals will absorb water from the air and grow. For this to happen, the water must be so cold that freezing it needs only a suitable surface. Loss of moisture in the air increases the evaporation rate of water droplets in the cloud, and they are scattered, forming a hole.

Become heavier ice crystals continue to fall and form a sparse, wispy like cloud precipitation, which can be seen inside and under the hole. Water and ice in these sediments evaporates before reaching the ground.

Source — Obozrevatel Abovetopsecret