Colorful auspicious clouds appear in Changsha. What wonderful clouds have you seen?

1. Rain Banner Cave Cloud

Rain Banner Cave Cloud, also known as Cave Cloud, is a wonder of nature. It refers to a cloud hole with a diameter of about hundreds of meters. The shape is like the scene in the science fiction blockbuster "Independence Day" when alien spacecraft invade the earth. When propeller planes or jets pass through under the right atmospheric conditions, they cause liquid water droplets to condense and immediately fall like snowflakes, forming a circular rift, creating cloud holes, and causing rainfall. Together with roller clouds, lenticular altocumulus clouds, hat clouds, horseshoe-shaped swirl clouds, mammalian clouds, and spray clouds, it is collectively known as the top ten strange cloud landscapes. On January 19, 2015, cloud holes appeared over manholes in Fuyong, Baoan, Shenzhen and over Zhuhai.

2. Roller clouds

Turbulent altocumulus-type clouds formed in the downwind direction of large mountain tops. The airflow in the cloud rotates around an axis parallel to the mountains. Roller clouds are horizontal, tube-shaped clouds that usually herald the coming of a storm, and rarely appear at the end of a storm. As a storm approaches, cold downdrafts expand to form roller clouds. This rapidly sinking air mass can hit the land surface, creating strong air currents that can reach very long distances. The cold air will slide under the hot air layer and be sucked up by the storm's vertical updrafts. The roller cloud will then condense the vapor in the hot air flow to form a cloud layer. Eventually, the roller clouds will separate from the storm's main cloud layer. Roller clouds are very dangerous. The updraft and downdraft speeds produced by roller clouds have been measured to exceed 1,500 meters per minute.

3. Altocumulus lenticularis

Altocumulus clouds are shaped like lenses or pods and have clear boundaries. They are often composed of many individuals connected into cloud sheets. Altocumulus lenticularis form when stable moist clouds are lifted high into the sky and the moisture in them condenses to form clouds. If there is an exchange of layers of moist and dry air, the clouds will form vertical structures. Altocumulus lenticularis usually form where there are updrafts below and downdrafts above. Once it passes through the obstacle, the lenticular cloud will return to its original state and form a standing wave shape in the air, located on the side of the mountain. As shown in the picture, this is a lenticular cloud appearing in the Rainier Mountains in Washington, USA.

4. Wave cloud

Wave cloud is a wonder of nature, which refers to a type of cloud that can form the shape of miniature wave peaks. As this cloud structure extends down toward the island, it resembles ripples left by a ship crossing the water, extending hundreds of kilometers and eventually blending northward into the edge of the cumulus clouds. It, together with rain banner hole clouds, roller clouds, lenticular altocumulus clouds, hat clouds, horseshoe-shaped swirl clouds, mammatus clouds, and spray clouds, are collectively known as the top ten strange cloud landscapes.