Hint:All air contains water, but it is usually in the form of an invisible gas called water vapour near the atmosphere. It expands and cools as warm air rises. Cold air is not capable of containing as much water vapour as warm air, so some of the vapour condenses into tiny pieces of dust floating in the air, creating a tiny droplet around each particle of dust. It becomes a visible cloud as billions of these droplets come together.
Clouds are a cluster of solidified liquid droplets, solid particles or crystallized particles suspended or floating in the air with a light pigmentation in appearance. These are present in the homosphere of the earth which consist of the troposphere, stratosphere, and mesosphere. They appear in various shapes including sheet form or ripple form based on the density of the atmosphere and climatic conditions. Clouds are formed when water droplets in vapor form get absorbed into air through evaporation majorly from the water bodies like ocean and rivers, these water droplets travel in the air in a condensed form. When air volume increases, it rises in the atmosphere. After a while, it gets cooler. As the air gets cooler, it’s ability to content all of the water vapor within itself loses. And it changes into small water droplets or ice crystals and a cloud is formed.
There are two types of clouds when considering location where they are formed and shape. High clouds and Low clouds. High clouds are formed on the upper part of the sky. Low clouds are formed on the lower part of the sky, generally from within a kilometre or two of Earth's surface. They are sometimes called fog. Middle-level clouds form between low and high clouds.
Note:There are Clouds present in the atmospheres of other planets and moons in the Solar System and beyond. These include Neptune, Mars and Moons. However, due to their different temperature characteristics, they are often composed of other substances such as methane, ammonia, and sulfuric acid, as well as water. They are highly toxic in nature and highly dense.