A rare weather phenomenon left residents of a small Australian town in awe last month. A large, circular hole appeared in the cloud cover, creating a rainbow effect in the sky. Meteorologists were equally excited as they knew they had witnessed an extremely rare occurrence – a hole punch cloud. However, the exact cause of these cloud holes is still unknown.
Hole punch clouds, also known as fall-streak clouds, are a rare sight. There are only a few photos of such weather phenomena, and their general awareness is quite low. Due to this, cloud holes are often misinterpreted as UFOs – as was the case in Wonthaggi. However, Australian meteorologists quickly identified the strange cloud as a fall-streak cloud. But none of the weather experts could explain the cause of this phenomenon.
To date, hole punch clouds remain unexplored. It is known that they occur mainly in winter, which leads to various theories. However, since cloud holes are so rare, their exploration is significantly hindered. There are various assumptions about what conditions could lead to the formation of fall-streak clouds. The most common hypothesis is that falling ice crystals are the cause of the weather phenomenon. These crystals could come from higher cloud layers or from airplane engines and create holes in the cloud cover as they fall.
In theory, the water droplets of the cloud in question are highly cooled, as is typical in winter. When ice crystals fall from above onto the cloud, they extract moisture from the environment. The droplets bind together, the crystals grow, and a hole is created in the cloud cover. Additionally, a fall streak is formed, consisting of the aforementioned ice crystals, which is often mistaken for a tornado funnel. However, there is no snowfall on the ground as the fall streak is warmed in lower air layers, causing the ice crystals to evaporate. The oval shape of the hole remains unexplained, and this is just one of many theories about hole punch clouds.
