Strange tsunami clouds dancing in the sky

The sky was dark and looked like a nightmare for all the sea people, though the clock was only 10am.

This strange phenomenon happened over the weekend in Alabama, USA. A long row of huge waves, billowing up in the horizon and slowly sweeping forward. The Alabama people were frightened, shocked, and captured the scene and sent it to the local hydro-meteorological station. Police hotlines and authorities are continuously blocked. The most asked question, obviously, what does it mean to be the tsunami scene in the sky? Is it a catastrophe? "

However, experts believe that these tsunami clouds are the typical example of the "Kelvin - Helmholtz wave" , formed when two layers of air collide. Whether recorded in the sky or under the ocean, this disturbing motion is always formed when a fast-moving 'liquid' layer slides up on another thicker layer, moving more slowly.

In this case, the lowest atmospheric layer (50-100) is closer to the ground with higher stability than the upper atmosphere in the morning. As long as the ground temperature has not increased due to the heat from the sun, the lower layer is still more stable than the upper floor. Kelvin-Helmhotlz waves will occur when the wind passes through these layers, destabilizing the top of the bottom layer and adding air to the vibrating layers. As a result, the stable gas layer is raised, cooled and condensed. To a certain extent, the whole process will become visible and create strange shapes in the sky.

Similarly, water waves will form when the upper 'liquid' layers (eg air) move faster than the 'liquid' layers below (eg water). When the difference between the speed of wind and water rises to a certain extent, the wave will break and form the Kelvin-Helmholtz sequence (named after two German scientists who discovered this phenomenon).

Previously, meteorologists also collected many strange cloud images caused by Kelvin-Helmhotlz waves.