The Perils of Plastic Manufacturing

The United Nations Environment Programme reports that humanity produces 400 million tonnes of plastic waste each year, including five trillion plastic bags annually. (UNEP, 2022). Plastic is used everywhere, but how is this crucial material made? The first step in creating plastic is the extraction of raw materials, which mostly come in the form of crude oil and natural gas. Even the first step of creating plastic is bad for the environment as the extraction of these resources can disrupt ecosystems and damage the soil which causes mudslides and flash floods. Additionally, extracting these materials releases harmful toxins into the atmosphere. (Conservation Law Foundation, 2021).

The next step in creating plastic is refining the raw materials. If crude oil is being used, then the process of refining involves separating the many chemicals in the crude oil. This is done by heating the crude oil until it becomes a gas which then flows into a tower that is hotter at the bottom and colder at the top. As the gas floats up the tower, the crude oil is separated based on the molecular weight and boiling point of the chemicals in it. If the material hardens at over 350°C then it becomes asphalt, if it hardens between 220°C-250°C it becomes diesel fuel, and if it hardens between 60°C-180°C it becomes a material known as naphtha,the main ingredient in plastic. (Baheti, 2021).

Next, the naphtha goes through a process called polymerization. In this process, a class of substances known as olefin gasses, which include ethylene, propylene, and butylene, are involved. These are called monomers and when bonded together they form chains of carbon atoms called polymers. There are two types of polymerization: addition polymerization, which adds one monomer at a time, and condensation polymerization, which can combine multiple chains of carbon atoms. The polymers are then blended with other chemicals to form plastic pellets, which are used to make plastic. (Sharpe & Baheti, 2015).

In addition to oil, natural gas can also be used to produce the polymers needed to make plastic. When natural gas is used, it is fed into an ethane cracker. An ethane cracker is a facility that uses extreme heat to break the molecular bonds in natural gas, producing ethylene, which is a monomer. There are about 30 ethane industrial facilities located from the Ohio River Valley to the Gulf Coast that process the raw material into the desired monomer. These “crackers” are incredibly dangerous for the surrounding area as tiny pellets produced by these factories often get into local rivers and waterways which are then eaten by birds and fish. The factories can also spill chemicals into rivers and oceans, which is extremely dangerous to fish and wildlife. For instance, federal biologists have warned that a proposed cracker plant in Texas could threaten an endangered species of crane. Ethane factories have also released harmful air pollutants into surrounding communities. These pollutants can cause childhood leukemia, cancer, infant mortality, and brain tumors, as well as damage the climate as a whole. (The Climate Reality Project, 2018).

Plastic production starts with extracting raw materials like crude oil or natural gas, which are refined through energy-intensive processes that emit harmful pollutants. This leads to environmental damage through habitat destruction, pollution, and the long-lasting impact of plastic waste on ecosystems and wildlife. We absolutely need to develop better methods for processing raw materials or find alternatives to plastic that are less harmful to the environment.

Works Cited

Dr. Baheti, P. How is plastic made? A simple step-by-step explanation. British Plastics Federation. https://www.bpf.co.uk/plastipedia/how-is-plastic-made.aspx#[1%20NEW]

Bryce, E. (2021, January 18). How do we turn oil into plastic?. LiveScience. https://www.livescience.com/how-oil-is-turned-into-plastic.html

Conservation Law Foundation. (2021, September 8). How plastic is made is harmful to people and the environment. https://www.clf.org/blog/how-plastic-is-made/

Ethane cracker plants: What are they?. The Climate Reality Project. (2018, October 23). https://www.climaterealityproject.org/blog/ethane-cracker-plants-what-are-they#:~:text=Ethane%20crackers%20are%20plants%20that,plastics%20and%20other%20industrial%20products.

Sakashita, M. (n.d.). The plastic-production problem. The Plastic-Production Problem. https://www.biologicaldiversity.org/campaigns/plastic-production/index.html#

Sharpe, P. (2015, September). Making plastics: From monomer to polymer. AIChE. https://www.aiche.org/resources/publications/cep/2015/september/making-plastics-monomer-polymer#fig1

Visual feature: Beat plastic pollution. UNEP. (2022). https://www.unep.org/interactives/beat-plastic-pollution/

What are monomers, polymers, copolymers, and homopolymers?. What are monomers, polymers, copolymers, and homopolymers? | U.S. Plastic Corp. (2008, August 28). https://www.usplastic.com/knowledgebase/article.aspx?contentkey=510&srsltid=AfmBOop_9mzkwdSb1nvDZ4aN4hi33gK2QxV6tNIS4xxKiPAuxFFrWSlH

Nitrogen-Caused Phenomena in Diving

Have you ever wondered how divers are able to dive so deep with little repercussions? Diving at its core, is a basic maneuver that many people can perform without tools. However, the perspective shifts when one intends to dive deeper. Deeper dives require divers to bring essential equipment, such as air tanks and goggles. However, this equipment is simple only in its rudimentary form. In reality, divers seeking to dive deep must bring many gas cylinders with different gasses based on their dive depth in order to avoid nitrogen narcosis, a temporary condition that can cause dangerous changes in consciousness and neuromuscular functionality. It often occurs due to nitrogen building up in the body faster than the body can absorb it (Kirkland et al., 2023). 

According to Boyle’s Law, which states that PV=K, which states that pressure multiplied by volume equals a constant K. The increase of pressure causes gas volume to decrease, therefore increasing the density of the gas. This means the effects of gasses grow relative to the pressure increase caused by the depth. At a depth of ten meters, the effect of gasses will double, at twenty meters, it will triple, and so on (NOAA, 2019). Therefore, the deeper a diver goes, the more nitrogen they will breathe in. The nitrogen eventually becomes too much for the body to absorb, resulting in nitrogen narcosis. When diving, the total pressure of gas increases by one atmospheric pressure (atm) every ten meters. Total gas pressure is the pressure that the gas compound exerts. When discussing the pressure exerted by one gas exclusively in a compound of gasses, scientists refer to it as the partial pressure of the gas. This means that, according to Dalton’s Law of Partial Pressures, the increasing total pressure of a mixture results in the increase of the partial pressure of each gas it contains. Nitrogen causes narcosis after a partial pressure of three atm, and oxygen is toxic above a partial pressure of 1.4 atmospheres, meaning that hypothetically, a 100% nitrogen mixture will become toxic at twenty meters deep (disregarding breathability) and a 100% oxygen mixture will become toxic at four meters deep (14.14: Dalton’s Law of Partial Pressures, n.d.).

When first entering the water, divers use tanks of compressed air to breathe. Compressed air is made of about 79% nitrogen and 21% oxygen (with traces of other gasses). However, due to the narcotic effect of nitrogen, a diver is forced to decrease nitrogen intake by using gasses with a lower concentration of nitrogen to be able to go deeper.

Once a diver reaches a depth of 38 meters, nitrogen levels should be reduced to prevent the increasingly narcotic nitrogen from causing nitrogen narcosis. To do this, divers at this depth switch to Nitrox, which is again a mixture of nitrogen and oxygen, but this time include less 78% nitrogen, though more commonly contain 64-68% nitrogen (“Probing the Limits of Human Deep Diving,” 1984). With a lower concentration of nitrogen, the effect of narcotic nitrogen is further reduced. Oxygen toxicity, harmful effects on the body caused by breathing oxygen at high pressures, can become a worry at a depth of about forty meters. After this depth, a diver should switch gasses once again in order to continue a safe journey (Wilmshurst, n.d.).

Trimix is a breathing gas that also increases nitrogen and oxygen, similar to its counterparts Nitrox and compressed air. However, it also includes another gas, helium. It is most commonly composed of 21% oxygen, 44% nitrogen, and 35% helium, but Trimix compositions vary significantly. Since many Trimix mixtures use oxygen percentages below the normal survivability level for humans, Trimix should only be used starting at various depths depending on the mixture used (Dive SAGA - Scuba diving, 2023). 

Decompression sickness (DCS), is another diving phenomenon that can cause effects similar to that of nitrogen narcosis. Decompression sickness occurs during the ascension part of the dive when the nitrogen absorbed by the body during descent floods too quickly into the bloodstream, clotting it (Harvard Health Publishing). Divers avoid this by making decompression stops along the ascent. When a diver is at the bottom of their dive, every minute spent at the bottom increases their decompression time by four minutes. Therefore, divers must bring extra gasses to support themselves throughout the decompression.

Although nitrogen narcosis and DCS can occur at various depths depending on what gas is used, some divers may have some natural resistance to these effects. One example of this phenomenon is Sheck Exley. Sheck Exley was a scuba diver in the late 20th century who had an unusual resistance to nitrogen narcosis. Due to this extraordinary resistance, he was able to dive 120 meters using only compressed air. Sheck is one of only a few divers who has ever accomplished this feat (Sheck Exley: A Cave Diving Pioneer, 2016).

In practice, divers often use a number of different tactics to avoid oxygen toxicity, DCS, and nitrogen narcosis. Often used in cave diving or other situations where a direct ascent is not possible, one of these methods is known as the rule of thirds. The rule of thirds is a practice involving using one third of a divers gas reserve on the way down, one third on the way back to the surface, and saving the last third for reserve in case of emergency. Another technique used to prevent these conditions is by using safety stops. Safety stops are gas cylinders placed at specific places throughout the dive which assist by acting as decompression stops as the diver ascends at the end of the dive, which often takes hours (Suzee Skwiot, 2023). Another important reason why divers use this method is to decrease weight. While increased weight initially helps with a quick and easy descent, the diver must leave some gas cylinders at decompression stops to ensure an easy ascent.

Ultimately, while diving may seem like a simple task, there are numerous different obstacles that a diver must overcome to reach deep depths when diving. While a quick dip in the water will not need any complicated gas, it is important to distinguish what types of gasses may be needed in order to stay safe at deeper depths.

References

A couple of fire hydrants sitting next to each other. Diving cylinders water. - PICRYL - Public Domain Media Search Engine Public Domain Search. (2017). PICRYL - Public Domain Media Search Engine. https://jenikirbyhistory.getarchive.net/media/diving-cylinders-water-039b17 

14.14: Dalton’s Law of Partial Pressures. (n.d.). Chem.libretexts.org. Retrieved November 9, 2024, from https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/14%3A_The_Behavior_of_Gases/14.14%3A_Dalton's_Law_of_Partial_Pressures#:~:text=If%20the%20overall%20atmospheric%20pressure,the%20air%20is%200.21atm. 

Dive SAGA - Scuba diving. (2023, May 5). TRIMIX Diving to 120 meters 400 feet // Does it make sense? YouTube. https://www.youtube.com/watch?v=mFjiWn1EhO8 

I don’t have nitrogen narcosis. (2025, January 9). Flickr; I don’t have nitrogen narcosis | These were taken by the div… | Flickr. https://www.flickr.com/photos/raveller/1269280068 

Focus Physics and physiology of SCUBA diving Grade LeveL Focus Question. (2007). https://oceanexplorer.noaa.gov/edu/lessonplans/breath.pdf 

NOAA. (2019). How does pressure change with ocean depth? Noaa.gov. https://oceanservice.noaa.gov/facts/pressure.html 

Probing the limits of human deep diving. (1984). Philosophical Transactions of the Royal Society of London. B, Biological Sciences, 304(1118), 105–117. https://doi.org/10.1098/rstb.1984.0013 

Sheck Exley: A Cave Diving Pioneer. (2016). Just Gotta Dive (JGD). https://www.justgottadive.com/company/jgd_blog/sheck-exley-cave-diving-pioneer 

Harvard Health Publishing. “Decompression Sickness - Harvard Health.” Harvard Health, Harvard Health, 2 Jan. 2019, www.health.harvard.edu/a_to_z/decompression-sickness-a-to-z. 

Shreeves, K. (2024, June 11). Practical Guide to Nitrox Diving. Scuba Diving. https://www.scubadiving.com/nitrox-scuba-diving-guide-certification 

Suzee Skwiot. (2023, June 2). Scuba Diving Safety Stops: Why They’re Important - Scuba.com. Scuba.com. https://www.scuba.com/blog/scuba-diving-safety-stops/?srsltid=AfmBOoq7M-cib7SOGddU3PRH3q9WQdgnqObnFn6IQIhOvK2w-DBLcYrN 

Wilmshurst, P. (n.d.). Diving and oxygen. Pubmed. Retrieved November 10, 2024, from https://pmc.ncbi.nlm.nih.gov/articles/PMC1114047/ 

(n.d.). (n.d.). Kirkland PJ, Mathew D, Modi P, et al. nitrogen Narcosis In Diving. [Updated 2023 Jul 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470304/ 

Digestion

How can speed-eaters push their digestion tracks to such extreme limits?

Every year, thousands of speed-eaters compete in competitive eating competitions, with some being able to consume over 20,000 calories in 10 minutes. Digestion is a process everyone experiences, yet many may not think about its complexity. After eating multiple times throughout the day, you might find yourself feeling extremely hungry or even unwell at the thought of food. Many mechanical processes during digestion convert food we eat into nutrients our body needs. An adult body needs between 1600 and 3000 calories in a day, but the body can only eat a certain amount of food until feeling full (Cleveland Clinic, 2023). 

Digestion is made up of many different systems all working together to be efficient and provide for the body. It begins when the food is chewed and mixed with saliva, which contains salivary amylase, an enzyme that begins the process of breaking down carbohydrates into simple sugars. The resulting product is a soft mass called bolus. The bolus then travels through the esophagus by muscular contractions into the stomach. The bolus is then mixed with gastric juices, including hydrochloric acid and pepsin, another enzyme that begins breaking down proteins (Cleveland Clinic, 2023). During mechanical digestion, the stomach transforms the bolus into a semi-liquid substance known as chyme. The chyme then enters the duodenum, the start of the small intestine, where most digestion and nutrient absorption happens. In the duodenum, bile helps enzymes break down fats by reducing them into smaller pieces. This allows pancreatic enzymes, such as amylase, lipase, and proteases, break down carbohydrates, fats, and proteins into their simplest forms. The nutrients are then absorbed and sent to the liver, which processes and sends the nutrients throughout the body for energy, growth, and repair. Any remaining undigested food enters the large intestine, where most of the remaining water and electrolytes are absorbed. The large intestine contains beneficial bacteria that help digest fiber and other indigestible material. These bacteria ferment undigested carbohydrates and fiber, producing short-chain fatty acids that can be absorbed for energy (Cleveland Clinic, 2023).

 The digestion process is the same for nearly all people; however, there's an exception for speed-eaters. During competitions, speed-eaters have to consume a large amount of food, which the normal digestion process wouldn’t be able to handle. Speed-eaters have to alter their digestive system to consume large quantities of food. Eating is like all sports; it requires years of training to master in order for the body to perform well. Competitive eaters train for years, consuming large amounts of food and pushing through even when full. The results of this training involve altering gastric physiology. This alteration allows the stomach to expand and hold a large amount of food (Balthazar, 2007). This process happens because the stomach progressively expands into a giant flaccid sac occupying most of the upper abdomen. Additionally, the gastric peristalsis process, which facilitates the breakdown of food, is absent, ensuring that nearly none of the consumed food enters the duodenum, where most digestion occurs, enabling speed-eaters to continue eating. 

Competitive eating completely alters the normal digestion process, leading to substantial changes in the body. When the stomach begins to enlarge without food entering the duodenum, the body does not register fullness, allowing the speed-eater to consume more. While this is advantageous in competitions, it also means speed-eaters may never feel full and satisfied in normal life. They must be very careful with their eating habits, following strict dietary plans, as their bodies do not send standard signals to the brain that indicate fullness. If speed-eaters are not careful and eat indiscriminately, they risk developing morbid obesity (Balthazar, 2007). The issue extends beyond monitoring food intake; it also concerns stomach size. One significant worry is that a speed-eater's stomach may struggle to return to its normal size, potentially leading to nausea and vomiting and may even require surgical intervention (Balthazar, 2007). 

Digestion is similar in most individuals, but some have learned to change their digestive systems to consume a large amount of food through years of training. Competitive eaters are able to stop the flow of food into the duodenum, allowing them to eat beyond normal limits, albeit with potential consequences (Balthazar, 2007). Altering the digestive system has many implications for competitive eaters in their daily lives. Competitive eating may push the body to extreme limits, but it constantly challenges participants to maintain balance and avoid long-term health issues.

References

Balthazar, E. J. (2007). Imaging of the digestive system. American Journal of Roentgenology, 188(3), 609–620. https://doi.org/10.2214/AJR.07.2342

Cleveland Clinic. (2023, August 22). Digestive system. Cleveland Clinic. https://my.clevelandclinic.org/health/body/7041-digestive-system

Fox 11 News. (2023, July 4). Joey Chestnut’s calorie count at the Nathan’s hot dog eating contest revealed. FOX 11 Los Angeles. https://www.foxla.com/news/joey-chestnuts-calorie-count-at-the-nathans-hot-dog-eating-contest-revealed

National Institute of Diabetes and Digestive and Kidney Diseases. (2017, June). Digestive system: How it works. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works

Science Learning Hub. (n.d.). Digestion chemistry: Introduction. Science Learning Hub. https://www.sciencelearn.org.nz/resources/1826-digestion-chemistry-introduction

Essential Oils: The Secret to Healing?

While essential oils are not essential to our daily lives, are they a magical solution to healing and relaxation? Essential oils are a special type of oil, usually made from a plant or flower, that contains the essence or smell of that plant or flower. Due to the strength of the scent, essential oils are often used in aromatherapy. Whether in a grocery store, at the spa, or in general conversation, many have either heard about or seen essential oils before. Common smells include but are not limited to: lavender, rose, rosemary, peppermint, or frankincense (Cleveland Clinic, 2021). These essential oils and many others have been used in the past as part of healing remedies, traditional ceremonies, part of relaxation, and much more.

Essential oils are either made naturally through plants or synthetically through chemicals. The former are generally claimed to be more “pure” and have better and more potent effects. The process of extracting essential oils is very intensive and requires many plants if made naturally. For example, it takes around 250 pounds of lavender flowers to make one pound of essential oil. Natural essential oils are obtained through distillation or mechanically pressing the oils out. Distillation is the process in which a mixture boils a specific substance and collects it separately by rapidly cooling the collected vapor into liquid. Once the aromatic chemicals have been extracted, they are combined with a carrier oil to create a product that’s ready for use (Healthline, 2019). Essential oils are made of many complex substances, such as phenols, alcohols, aldehydes, and esters (NAHA, 2015). Some of these complex substances help give the essential oil its characteristics, such as being soluble in alcohol, ether, and fixed oils but not in water. Essential oils are also usually liquids at room temperature and colorless too (MDPI, 2016).

In natural essential oils, the chemicals come from inside the plants, usually located in the cytoplasm of different organs in the plant. These organs are mostly the secretory hairs or trichomes, epidermal cells, internal secretory cells, and secretory pockets. These natural oils generally have a low molecular weight and are made up of very complex organic compounds. Some oils contain as many as 300 compounds. These complex compounds are considered to be from many chemical classes, such as “alcohols, oxides, aldehydes, ketones, esters, amines, amides, phenols, heterocycles, and mainly terpenes. Alcohols, aldehydes, and ketones offer a wide variety of aromatic notes, such as fruity ((E)-nerolidol), floral (Linalool), citrus (Limonene), herbal (γ-selinene)” (MDPI, 2016).

Once obtained, essential oils have many purposes, mainly for relaxation and healing using aromatherapy. Aromatherapy is the process of healing through the use of aromas or smells. Studies show that breathing in the scents from essential oils can stimulate the limbic system, a part of the brain that plays a role in emotions, behaviors, sense of smell, and long-term memory (Healthline, 2019). The limbic system's involvement with smell and memory can be the reason why sometimes smelling strong scents can invoke memories from your childhood. Studies have also shown that essential oils used though aroma therapy may help with boosting mood, improving sleep, reducing stress, anxiety, and headaches (Cleveland Clinic, 2021).

Essential Oils have been used throughout history as a home remedy for sicknesses and used in spas and saunas for relaxation. The history of essential oils spreads far and wide, with some even going back to ancient Persian remedies. Although there is not 100% certainty throughout the scientific community around the effectiveness of the oils, their long history and overall use seem to imply that they can be used for these applications and do work to some extent. There are many different types of essential oils, and each has its own properties. Still, perhaps there is more to them than what meets the eye, and one day we may learn more about essential oils that could revolutionize the world.

References

Cleveland Clinic. (2021, December 14). 11 essential oils: Their benefits and how to use them. Cleveland Clinic. https://health.clevelandclinic.org/essential-oils-101-do-they-work-how-do-you-use-them

Dhifi, W., Bellili, S., Jazi, S., Bahloul, N., & Mnif, W. (2016). Essential oils’ chemical characterization and investigation of some biological activities: A critical review. Medicines, 3(4), 25. https://doi.org/10.3390/medicines3040025

Exploring Aromatherapy | NAHA. (2015). Naha.org. https://naha.org/explore-aromatherapy/about-aromatherapy/what-are-essential-oils//

West, H. (2019, September 30). What Are Essential Oils and Do They Work? Healthline. https://www.healthline.com/nutrition/what-are-essential-oils

K is for constant

Almost every middle and high school student has seen a chemical equation written out. When they imagine what that looks like, they probably know an equation filled with letters that have one arrow in the middle. However, most chemical equations actually have two arrows because they are equilibrium reactions. An equilibrium reaction is a reaction in which reactants and products are being created at an equal rate, hence equilibrium. This does not mean that the same amount of reactants and products are created, just that they are created at the same rate, or speed. To understand the amount of reactants and products created when a reaction reaches equilibrium, the constant, K, is used.

The equilibrium constant is determined by the ratio of the concentration of the products and the concentration of reactants. Some of the most common equilibrium constants are for acids and bases, as those are the most commonly occurring equilibrium reactions. The constant for an acid will always involve the concentration of hydrogen ions and hydroxide ions for bases. Since water dissociates into hydrogen and hydroxide, it also has a K value that remains constant at 10^-14. While K never has units, the magnitude of the number can say a lot about an equation. A very large K value means that way more products than reactants are being produced and the other way around for a small value. Given that equilibrium reactions occur everyday, in and out of the lab, understanding how they work is very important. Whether it be the air we breathe or the water we drink, almost everything is at an equilibrium.

The Spark of Fireworks

Fireworks are seen year-round and have become a staple in large-scale celebrations. New Year’s Eve and July 4th are two of the most notable examples of fireworks. The fireworks fill the night sky with bright and vibrant colors, but how do fireworks work? How do scientists know what element to use to achieve different colors? At the base of all fireworks is black powder, composed of potassium nitrate, carbon, and sulfur, which when ignited releases immense heat, causing gasses to expand and eventually send little pellets of metallic powder into the air (Brockmeier, 2019). 

As the pellets fly into the sky, the energy released by the black powder puts the electrons inside the metal into a state of “excitement.” However, atoms naturally seek to be in a state of stability, in order to revert to this state, the electrons will get rid of the excess energy by emitting wavelengths. These wavelengths present themselves as colors. Each element has distinct spacing between its energy levels. The metals that have larger spacing between the energy levels will emit shorter wavelengths, which often present themselves as blues and purples. Conversely, atoms with shorter distance between the energy levels will emit longer wavelengths which tend to be oranges and reds (Lutz, 2019). Understanding the science behind fireworks allows us to appreciate even more the bright and colorful displays that light up joyous occasions.

References: 

Brockmeier, E. K. (2019, July 1). The chemistry behind fireworks. Penn Today. Retrieved April 1, 2024, from https://penntoday.upenn.edu/news/chemistry-behind-fireworks

Lutz, A. (2019, July). Exploding Colors: The Science Behind Fireworks. The College Today. https://today.cofc.edu/2019/07/01/fireworks-fourth-of-july 

Cloud Formation

Water vapor, which is a result of evaporation, is one of the key components in the formation of a cloud. Cloud formation is a result of rising air; this occurs when the ground warms air, or when air is forced up when wind blows into the side of a terrain, such as a mountain. These two ways of air rising create different types of clouds. The former creates types including cumulus, cumulonimbus, mammatus, and stratocumulus clouds; and the latter creates lenticular and stratus clouds. Air may also rise when two large masses of air collide, giving them no choice but to go up.

In any case, rising air causes pressure and temperature to drop, making the water vapor within it condense. This occurs because as air rises, it expands due to the lower pressure. The temperature decreases at 9.8 degrees celsius per kilometer until saturation, at which the water condenses to form clouds. 

Water molecules found in the air are too small to condense on their own. Therefore, particles found in abundance in the atmosphere become the surface on which these water molecules condense, called cloud condensation nuclei. Oftentimes particles of soil, dust, pollen, salt crystals and smoke become cloud condensation nuclei. These particles are at least one micrometer and 1/100 size of cloud droplet. They also must be hygroscopic, or able to attract and absorb water from the environment. Despite these particles forming the core of each cloud droplet, clouds are still considered to be pure water. 

When more water condenses than evaporates, clouds grow. When the opposite occurs, clouds dissipate. As the atmosphere is constantly changing, condensation and evaporation are constantly occurring on cloud condensation nuclei, leading to the formation and dissipation of clouds. 

References:

Clouds and How They Form. (n.d.). University Corporation for Atmospheric Research-Center for Science Education. Retrieved March 30, 2024, from https://scied.ucar.edu/learning-zone/clouds/how-clouds-form

How Clouds Form. (n.d.). National Oceanic and Atmospheric Administration. Retrieved March 30, 2024, from https://www.noaa.gov/jetstream/clouds/how-clouds-form