How are Clouds Formed?

Have you noticed when you hang up a wet towel how it dries after some time? You put aside a bowl full of water for your cat, and even though the kitty has been nowhere near the bowl, the water level in the bowl has dropped! Where do you think the missing water went? Well, it evaporated, which means that a part of the liquid water in the bowl or the towel drifted into the atmosphere by changing into the gaseous form, or water vapour. The same phenomenon is constantly occurring in the lakes, oceans, swamps, rivers, swimming pools, and wherever water is in contact with the atmosphere.

When the molecules of liquid water get extra energy from a source of heat like the sun or other water molecules that come in contact with them, they get converted into a gaseous form. The molecules with high energy then drift into the atmosphere in gaseous form. In the process where the water molecules change from liquid to gaseous form, they absorb heat that they carry into the atmosphere. Therefore, the water is left behind. 

Only a certain amount of water vapour can be held by the air, depending on its weight, temperature, and atmospheric pressure in the area. The greater the atmospheric pressure or temperature in the area, the more water vapour the atmosphere can hold. If a certain volume of atmosphere holds the maximum amount of water vapour it can hold, it is said to be saturated. 

So what do you think will happen when a saturated part of the air cools or if there is a drop in the atmospheric pressure? The atmosphere can no longer hold that water vapour. Therefore, the excess water vapour gets converted into a liquid or solid form (ice). This process by which water changes from the gaseous state to the liquid state is referred to as condensation. The process is referred to as deposition if gas gets directly converted into a solid state. These two processes are fundamental to the formation of clouds.

Types of Cloud Formation

Upcoming weather patterns depend on the physical structure, colour, and size of clouds. Based on the three levels of altitude that clouds are found at, the types of cloud formations are broadly classified into ten different categories. They are given below:

Altitude	Types of clouds
Low-level	Stratus, cumulus, stratocumulus
Middle level	nimbostratus, altocumulus, altostratus
High level	cirrocumulus, cirrus, cirrostratus

The tenth one in the types of cloud formations, called cumulonimbus, towers across the upper, middle, and lower atmosphere.

Another phenomenon similar to cloud formation occurs in the environment. It is called fog formation and occurs closer to the ground surface. Fog should not be confused with clouds, as even though their composition is similar to clouds, they are the byproduct of a completely different series of events. 

The Physics Behind Cloud Formation

The Physics behind different cloud formations is much more complex than the simple weather analysis based on the structure of these clouds. There are two major aspects of the concept behind cloud Physics:

Cloud-Scale: The evolution of clouds depends on their size, the environment that surrounds them, temperature, wind shear, and turbulence. 

Micro-Scale: The changes that occur within a few centimetres of the surface of the cloud help to determine the cloud scale. This tiny measurement and observation scale is referred to as the Micro Scale.

Mechanism of Cloud Formation

Clouds are made up of minuscule ice crystals and water droplets. Their weight is light enough to enable them to float in the atmosphere. They are formed as a result of different types of phenomena that occur in the atmosphere, such as:

Evaporation:

The water droplets from the Earth’s surface evaporate because of the temperature rise. These evaporated water droplets navigate in the atmosphere and keep on rising higher. When they rise higher, their temperature and air pressure fall. The water vapour at this point can not retain its gaseous state; therefore, it changes into water droplets and ice crystals which later change into clouds.

Condensation:

The water vapour sometimes carries dust particles and pollen grains with it. When they move higher, the water vapour changes into water droplets and settles on these particles, which are called condensation nuclei. Later, different cloud formations occur around them. Due to the high speed of the wind at high altitudes, sometimes the moist air is forced to rise higher and resulting in cloud formation. These phenomena are called the Leeward Side and Windward side.

When the wind blows in an area where the atmospheric pressure is low, and it is unable to move away, low-pressure clouds are formed. This results in a decrease in the temperature and pressure resulting in the formation of mid-altitude clouds.

When a larger volume of air with a higher temperature is pushed to a higher altitude by cold air, there is a sudden change in atmospheric pressure that results in the formation of different cloud formations that are extremely large and accompanied by thunderstorms. 

Cloud Formation Experiment

To understand the process of cloud formation better, let us conduct a practical cloud formation experiment demonstrating the process. The transformation of water droplets into a gaseous state can also be shown in the experiment. The water droplets can change into clouds following a change in the atmospheric condition at a higher altitude.

Materials required 

• Droppers
• Clean glass jar
• Blue food colour
• Water
• Shaving cream

Procedure

• Fill a glass with warm water until three-fourth level. Add shaving cream to the surface of the water at the top and fill it up to the brim. Once the shaving cream foam settles, move on to the next step.
• Mix food colour with a small volume of water in a separate bowl. Collect the diluted water with the help of a dropper and drop it very slowly on the shaving cream foam.

Result

This is when we can demonstrate the process of cloud formation through this rare cloud formation experiment. As the water vapours within the water are diluted with food colourant saturation, the formation of precipitation can be seen on the surface of the clear water at the base of the shaving foam.

We already know that cloud formation occurs due to the rise of temperature on the surface of the water vapour. This leads to evaporation of the water and urges it to rise to a higher level and then condense to form clouds. Similarly, there is an increase in the temperature of the warmer water in the jar, which also evaporates to some extent.

The water vapour moves higher and comes in contact with the cooler atmosphere above and therefore condenses on the shaving from particles. The mechanism of rare cloud formation is indicated by the bluish tint on the lower surface of the foam.

Observation

So, how does a cloud formed? Clouds are formed as a combination of millions of tiny water droplets that float in the atmosphere. Moreover, they form a natural barricade where infrared radiation can be absorbed and redistributed over a larger surface.

Conclusion

Although you have understood the basic mechanism of rare cloud formation through this blog, there are much more details that are yet to be learned. If you peek under a cloud’s exterior, you will realise that it is full of complexity. Understanding the world of clouds and how cloud form requires a thorough understanding of the whole atmosphere. Scientists are working tirelessly to gain this understanding with the help of instruments like those on Aqua, NASA’s Terra, CALIPSO, Aura, and CloudSat. Hopefully, we will be able to gain more knowledge about clouds in the future, which will help us understand climatic changes better.

Frequently Asked Questions

1. Why are clouds sometimes yellow in colour?

A) Sometimes, clouds appear yellowish. This is due to the presence of pollutants on the surface of the Earth, the majority of which include remnants of nitrogen dioxide from dump yard burning or forest fires.

2. How is the process of condensation facilitated?

A)  The process of condensation is facilitated by the tiny particles suspended in the atmosphere, such as salt crystals, dust particles, and bacteria. This is because these particles provide surfaces for the water vapour to settle after they change into a liquid form or ice crystals. When a large amount of these droplets accumulate, clouds are formed.

3. How are clouds important?

Clouds are crucial to the climatic changes that occur in the environment. Additionally, they are integral to balancing and maintaining the radiations of the Earth. Depending on the climatic changes and the cloud intensity, there are fluctuations in the short and long wavelength radiations. As how does cloud formation is a major topic in various branches of Science, it means that they have much higher importance than just simple structures deciding the type of rainfall an area can experience.