What weather phenomenon indicates that it is going to rain?

The appearance of cirrocumulus, Fort Cloud, Cotton Cloud and Gray Cloth Cloud indicates that it will rain.

Cirrocumulus:

Cirrocumulus is a kind of cloud with an altitude of about 5500 meters. The clouds are small and there is no white shadow. It is a cloud sheet or cloud layer composed of white fine waves, scales or spherical clouds, which are often arranged in rows or groups, much like small ripples caused by small winds blowing on the water.

White without shadow, silky luster. Clouds are thin, can penetrate sunlight and moonlight, are white without dark shapes, are gray-black at night, and are almost entirely composed of ice crystals.

The formation process of cirrocumulus:

Cirrocumulus can be evolved from cirrus and cirrostratus. Sometimes cumulus clouds can evolve into cirrocumulus. Clouds are small, white and flaky, often in rows or groups, arranged neatly, like small ripples caused by a breeze blowing over the water. Convolution flowers have only 1 categories. ?

In addition, each kind of cloud has its particularity, but it is not static. Under certain conditions, this cloud can be transformed into that cloud, and that cloud can be transformed into another cloud. For example, light cumulus clouds can develop into thick cumulus clouds and then into cumulonimbus clouds; The top of the cumulonimbus is detached and becomes a pseudo cumulonimbus or cumulonimbus; Cirrocumulus descended to the upper clouds; The lowering of high-altitude clouds will turn into nimbostratus.

Another formation process of cirrocumulus may be that under the action of strong airflow, clip-like cumulus clouds rose to the sky and became cirrocumulus. After the appearance of this kind of cirrocumulus, there will often be strong winds of magnitude 4 or 5 before long. Generally, it won't rain, but it will remain sunny.

The influence of cirrocumulus:

If the sky clouds are mainly distributed in cirrocumulus, accompanied by cirrus clouds and cirrostratus, their interaction and system development usually indicate that there will be unstable weather systems affecting the station and rainy and windy weather will occur. The agricultural proverb "Fish-scale sky, even if it doesn't rain, the wind will jump" refers to such a cloudy day.