Clouds are visible polymers floating in the air composed of water vapor in the atmosphere that liquefies into small water droplets or condenses into small ice crystals when cooled. Clouds are the tangible result of Earth's vast water cycle. The sun shines on the surface of the earth;
Water evaporates to form water vapor. Once the water vapor is supersaturated, water molecules will gather around dust particles (condensation nuclei) in the air, and the resulting water droplets or ice crystals will Sunlight is scattered in all directions, which creates the appearance of clouds.
If the air continues to be lifted, excess water vapor will precipitate. If the temperature there is higher than 0°C, the excess water vapor will liquefy into small water droplets; if the temperature is lower than 0°C, the excess water vapor will condense into small ice crystals.
Extended information:
For thousands of years, the working people of our country have summarized a wealth of cloud changes in production practice based on changes in cloud shape, direction, speed, thickness, color, etc. He learned the experience of "looking at the clouds to know the weather" and compiled these experiences into proverbs.
“There are hook clouds in the sky and rain on the ground”: Hook clouds refer to hook cirrus clouds. Behind these clouds, there are often fronts (especially warm fronts), low pressure or low pressure troughs moving in, which is an omen. Rain is coming;
“Fort clouds, raindrops”: Fort clouds refer to fort-shaped altocumulus clouds or fort-shaped stratocumulus clouds. They often appear in front of low-pressure troughs, indicating that the air is unstable, usually every 8-10 seconds. A thunderstorm is coming around the hour.
"Clouds crossing clouds, rain showers": Clouds crossing clouds means that the upper and lower clouds move in different directions, that is to say, the wind direction at the height of the clouds is inconsistent. It often occurs near fronts or low pressure, so it indicates rain. Sometimes the direction of the clouds is opposite to that of the wind on the ground, and there is a saying that "when clouds move against the wind, the sky will change."
Reference: Baidu Encyclopedia --- Cloud