Clouds are part of the Earth's water cycle. Formed naturally due to the cooling of water vapor within the Earth's atmosphere, clouds are made up of billions of water particles. Clouds take on many shapes and forms, dependent on local weather systems and local terrain. Some of the most common cloud types include cirrus, cumulus and stratus.
Light from the sun hits the surface of the earth. A large part of the solar radiation is absorbed by the ground and gradually heats it up.
Constant heat reaching the surface of the ground causes air to heat up. The heated air becomes lighter, which causes it to rise above the cooler air which lies above it. This process is called convection.
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Rising hot air is pushed further upward by wind blowing over terrain such as mountains, or over cliffs onto land from the sea. This process is called Orographic uplift. Wetter areas are generally found near high terrain features, as the air cools at a quicker rate around these areas.
Air is also forced to rise at a weather front. This is due to the differing air masses of the two weather fronts. At cold fronts, cold air is pushed under warm air, forcing it upward and at a warm front, warm moist air is forced up and over the cold air. This process is called convergence or frontal lifting.
Clouds begin to develop in any air mass that becomes saturated. Saturation point is reached when the air reaches its frost point. At this point, air gradually cools, preventing it from rising any further. Water vapor molecules within air begin to clump together.
Water vapor condenses to form cloud droplets or ice crystals. This can be at various heights, which creates a variety of different cloud systems. Clouds contain millions of droplets of water or ice, depending on the temperature, which are suspended in the air.