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Weather can be predicted to a certain level by studying the clouds. Any planet of the solar system that has atmosphere will definitely have clouds. Besides Earth, clouds exist on other planets like Venus, Mars, Jupiter and Saturn as well. They are nothing but condensed droplets suspended in the atmosphere above the surface of the planet.

Processes of Cloud Formation

Clouds are formed when the air in the atmosphere is so saturated with water vapor that it cannot hold any more of it. This may happen under two conditions viz., the air has cooled down to a point where condensation is bound to take place because the air has expanded enough and has lost a considerable amount of its moisture content. And the quantity of water in the atmosphere had increased to such an extent that the air has no capacity to hold any more of it. The amount of water in the atmosphere may rise due to factors such as evaporation. Though cloud formation may seem as simple as condensation of water vapor in air, in reality the entire process is much more complicated. For the water vapor to condense at a particular point and form clouds, the moist air that rises above the earth's surface has to undergo a series of processes. Clouds thus, may be formed in five different ways. These include:

Heating of the Earth's surface
  • Heating of the surface of the Earth results in the formation of clouds.
  • When the ground heats up due to the heat of the Sun, it in turn heats the air around it.
  • This warm air due to heating thus reduces in density, and becomes lighter.
  • Because it becomes lighter, it begins to rise up in the atmosphere.
  • As it rises higher and higher into the atmosphere, it begins to expand, thus releasing the moisture content.
  • This released moisture content/water vapor begins to condense as the temperature goes on dropping at higher altitudes.
  • This condensed moisture from the air results in the formation of clouds.
  • The clouds that are thus formed are predominantly cumulus, stratocumulus and cumulonimbus.
Hills, mountains and terrains
  • The air that blows towards the mountains and other vertical landforms is forced to rise at high altitudes.
  • It thus expands, becomes cooler and begins to drain out its moisture content.
  • At considerable heights, this moisture content/water vapor begins to condense, thus giving rise to the formation of clouds.
  • The clouds thus formed are primarily lenticular clouds and stratus clouds.
Frontal
  • A front is a boundary that lies between warm air which contains some moisture content and cold air which is dry enough.
  • Frontal clouds are formed when two masses of air, each one of a different temperature, come in contact with each other.
  • Whether the mass of warm air is over the colder one or not, it expands anyway owing to the altitude at which it has risen.
  • Its expansion leads to its cooling and subsequent condensation of the moisture that escapes through. This condensation leads to the formation of clouds.
  • The clouds thus formed are cirrus, cirrostratus, altocumulus, stratocumulus, nimbostratus and stratus.
Convergence
  • When different streams of air flowing from different directions meet at a focal point, a sort of pressure is created at that point.
  • This pressure forces the air to flow in an upward direction, where all the streams flow alongside each other. In other words, they converge.
  • Again, like in all the other processes, the air cools, expands and lets out water vapor that condenses to form clouds.
  • This process primarily forms cumulus clouds and in some cases may give rise to small showers.
Atmospheric turbulence
  • Sometimes, turbulent weather conditions in the upper atmosphere pose as a hindrance in the way of free flow of air.
  • This causes the air to flow in a circular pattern owing to the fact that it cannot flow on its designated track.
  • When the warm air containing moisture rises up, and reaches the level where this atmospheric turbulence is happening, it cools down and the water vapor content in it condenses on the spot, thus forming clouds.
  • The typical examples of turbulent clouds are cumulus and cumulonimbus.

Formation of clouds can sometimes cause a cloud field. Cloud fields are simply a group of clouds, which sometimes take on a strategic shape which has its own characteristics. The 'Open Cell' is a type of cloud field which resembles a honeycomb. It has denser clouds in the middle and clearer clouds at the end.

The colors of clouds also vary and impart important information about the weather. The characteristic white color of clouds means that they were formed with warm air which contained water vapor. The gray or black clouds are formed when the droplets in the cloud combine to make bigger droplets and this happens as the cloud matures. Clouds also sometimes appear in beautiful shades of blue, yellow and green. They get these colors due to the interplay of light and shade that takes place during different times of the day.