A cloud in the shape of a mushroom cloud has Mexicans panicking

On the evening of April 17, residents of Saltillo, in the Chihuahua Desert, panicked as they gazed skyward: a huge cloud ofthunderstormresembling those created by the explosion of an atomic bomb, covered the sky with a deluge oflightning. The phenomenon, which belongs to the category of supercellsgenerated a high electrical activitywith hailstones 3 centimeters in diameter and torrential rains for several hours.

Why did this cloud take on such an impressive shape? This is a cumulonimbus capillatus incus with a very extended anvil: these clouds are the highest in the world and can peak at 15 or even 18 kilometers. The anvil (its top) rises so high that it reaches the tropopause. Its growth is then blocked and the air masses are forced to spread out, giving it this mushroom shape, slightly asymmetric due to wind of altitude which pushes it forward. It takes about 30 minutes to form.

An infrequent type of thunderstorm in April

Located in the northeast of Mexico in the state of Cohahuila, the city of Saltillo enjoys a subtropical climatevery rainy all year round: the most violent storms generally break out during the summer, during the season rains. Between July and September, storms are almost daily, but a storm as powerful as the one that occurred in Saltillo is an infrequent event in April.

In recent days, temperatures have been higher than average in this area, between 30 and 35°C (5 to 7°C above normal) and the arrival of cooler air has caused a violent conflict of air masses, hence the formation of thunderstorms.