On December 2, 2024, a striking natural occurrence mesmerized onlookers over Wichita, Kansas, as two unique formations known as cavum clouds appeared in the midlevel sky.

These fascinating structures were captured by the Operational Land Imager-2 aboard Landsat 9, showcasing a rare atmospheric event that evokes curiosity about the science of clouds.

Cavum clouds, often called hole-punch clouds or fallstreak holes, occur predominantly in mixed-phase midlevel stratiform clouds like altocumulus and altostratus, which form horizontally and in layers.

While they are relatively uncommon, these cloud formations are estimated to cover about 8 percent of the Earth’s skies.

The appearance of cavum clouds is particularly noted in winter, especially near busy airports, where they can disrupt pilot visibility.

But what causes these peculiar formations? Cavum clouds develop in midlevel clouds that contain supercooled water droplets—liquid water that remains unfrozen even at temperatures below the typical freezing point of 32 degrees Fahrenheit (0 degrees Celsius).

When planes fly through these cloud layers, they can create additional cooling around their wings.

This cooling can trigger the supercooled droplets to freeze, transforming them into ice crystals.

As these ice crystals multiply, they become heavy enough to fall from the cloud, leaving behind a visible space shaped like a circle or ellipse—hence the name cavum, Latin for “hollow.”

The void left by the falling ice crystals often gives rise to wispy trails of precipitation known as virga, which can further accentuate the striking appearance of the clouds.

Researchers have estimated that the atmospheric conditions necessary for cavum clouds to form exist around 3 to 5 percent of the time worldwide, with the likelihood increasing to 10 to 15 percent during winter months.

Interestingly, the angles of aircraft passing through the cloud layer play a significant role in determining the shape and size of the cavum that forms.

When planes approach at sharp angles, they produce small, circular cavum. Conversely, when the aircraft passes through at shallower angles, they generate longer “canal clouds,” characterized by extended virga trails.

Other variables, such as the cloud thickness, air temperature, and wind shear, can also influence the length and appearance of the cavum formations.

Wichita Dwight D. Eisenhower National Airport, an important hub, sees an average of 34 flights taking off daily.

This bustling activity contributes to the notable frequency of cavum cloud formations and makes it a compelling location for studying cloud dynamics and atmospheric conditions.

The scientific significance of cavum clouds extends beyond their aesthetic appeal.

Meteorologists and researchers study these phenomena to understand better weather patterns, cloud formation, and precipitation processes.

The insights from such observations could help improve weather predictions, aiding pilots and travelers in navigating winter weather conditions.

So, the next time you look up at the sky and see an unusual hole in the clouds, remember it might be a cavum—a fascinating intersection of meteorology and aviation that reminds us of the extraordinary forces in our atmosphere.

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