What weather does the hook cloud represent?

Hook cloud is a kind of cirrus cloud. The name comes from Latin, which means "curly hook", also known as the end of the sea. Hook clouds generally appear in the troposphere, with thin air and sparse air, with a height of 7 kilometers. Usually the temperature is between 40℃ and 50℃. When a warm front approaches, a hook cloud will appear, which means the arrival of rain belt.

Hook clouds belong to the Gaoyun family and are completely composed of ice crystals. From the appearance, it looks like a comma symbol. The cloud is tilted upward with a small hook or cluster at the top. It is mainly caused by laminar convection caused by the intersection of cold and warm air currents in the upper air. It is most common in the front of warm front cloud system and the front of closed front and high-altitude cloud.

Structural characteristics of hook cloud

1. Clouds have fibrous structure, often white, shadowless, silky luster, mostly in the form of silk strips, sheets, feathers, hooks, balls and anvil. Most of them are composed of ice crystals with a diameter of 10- 15 micron.

2. Hook cloud is thin and white. Clouds are often arranged in parallel, with small hooks or clusters at the top and long tails at the bottom, much like comma symbols. Hook Cloudtail is often caused by wind shear during the falling of ice crystals in clouds.

3. Hook clouds often appear scattered. If we move to the sky systematically and continue to develop, it indicates that there will be weather system influence, and even rainy weather may occur. Therefore, the proverb "There is a cloud in the sky and it rains on the ground" is circulated among the masses.

4. Hook clouds are formed under obvious wind shear. The hook head often indicates the upper layer with high wind speed, and the hook tail indicates the lower layer with low wind speed. Hook cloud can only be seen clearly from its side.