Why are there clouds in the sky?

The formation of clouds is mainly caused by water vapor condensation.

The process of cloud formation:

1, the water in the ocean, lake, plant surface and soil has been evaporating, turning into steam and entering the atmosphere. Wet air containing water vapor rises upward for some reason;

2. During the ascending process, as the surrounding air becomes thinner and thinner, the air pressure becomes lower and lower, and the ascending air volume will expand. When expanding, it consumes its own heat, so the temperature of the rising air should be reduced. As the temperature decreases, the ability to contain water vapor becomes smaller and smaller, the saturated water vapor pressure decreases, and the water vapor in the rising air quickly reaches saturation. When the temperature drops again, the excess water vapor adheres to the condensation nuclei suspended in the air and becomes small water droplets.

3. If the temperature is lower than 0 degrees Celsius, excess water vapor will condense into ice crystals or supercooled water droplets. They gather together and float in the air under the support of updraft, becoming clouds that we can see.