How was this strange cloud target created over La Palma?


Target-shaped cloud over Cumbre Vieja volcano,

Target-shaped cloud over Cumbre Vieja volcano,
POT

An image from the Aqua satellite of the POT captured from space the mysterious concentric wave pattern that appeared above the Cumbre Vieja volcano, on the island of La Palma, last weekend.

The eruption has not been energetic enough to inject large amounts of ash and gases into the stratosphere, where they can have strong and long-lasting effects on climate and weather. However, it has been strong enough to produce a rising column of emissions that helped form the noticeable pattern in the clouds that the MODIS instrument on the Aqua satellite took on October 1, NASA reports.

The target-shaped cloud was the product of a rising column of ash and superheated gases known as an eruption column.. The floating column of water vapor and other gases rose rapidly upward until it collided with a warmer, drier layer of air at an altitude of approximately 5.3 kilometers, according to INVOLCAN.

Spiral clouds captured by NASA.


Gravity waves

The unusually warm air above – a temperature reversal – functioned as a lid, preventing the volcanic column from rising higher. Instead, it flattened and spread horizontally.

Since volcanic eruptions often have natural ebbs and flows in their intensity, pulses in the upward flow of the volcanic column created concentric gravity waves as they hit the temperature inversion and spread outward. The process is similar to the way a stone falling into a pond creates ripples that spread outward.

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