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Accumulation of hole clouds over the Gulf of Mexico (image taken on January 30)

Photo: NASA Earth Observatory

As if a jellyfish were floating over the sea: This is roughly what the collection of so-called hole-punch clouds over the Gulf of Mexico off the west coast of Florida looks from space, which a satellite from the US space agency Nasa photographed at the end of January .

From below, NASA describes it, these formations looked as if a large round shape had been cleanly cut out of the clouds.

In the middle of the hole only fine bands of clouds can be seen.

How did this arrangement of clouds come about?

Some people speculate that flying saucers could be the reason for the bizarrely arranged clouds, so it could be an anomalous phenomenon.

But as is often the case, a simple scientific explanation is much more likely.

In this case, airplanes are probably the cause.

Two types of hole clouds in one image

A few years ago, researchers led by the University Corporation for Atmospheric Research (UCAR) took a closer look at the spectacular formations, as NASA reports.

To do this, they analyzed aircraft data, satellite images and weather models.

It turned out that the starting point of the special formations in the sky are so-called altocumulus clouds.

When aircraft fly through these clouds at a steep angle, small, circular cavities are created.

If the jets cross the clouds at a shallow angle, longer hole clouds form.

Both shapes can be seen in the NASA satellite image.

To a certain extent, you can see the trace of the aircraft through the clouds: According to the information, medium-high altocumulus clouds consist of very cold liquid water droplets.

These droplets remain liquid even when the temperature is below the typical freezing point of water at 0 degrees Celsius, it is said.

This is possible if the water droplets are particularly pure, i.e. do not contain any particles such as dust or pollen around which ice crystals would otherwise form.

This occurs more frequently in the Earth's atmosphere.

But when planes fly through the clouds, things look different.

The air that moves around the wings continues to cool.

The previously liquid water droplets in the air then form ice crystals.

This sets off a chain reaction: more ice crystals form around the first ice crystals.

At some point these become so heavy that they fall from the sky and leave a hole in the cloud cover, it goes on to say.

The falling ice crystals are then visible as a thin veil in the middle of the clouds.