Condensation

Condensation is the process of a substance in gaseous form transforming into its liquid form. It is the exact opposite process of evaporation, which is a familiar process like water boiling on a stove. Condensation impacts everyday life, while also being a high-level chemical and physical phenomenon. While condensation may occur with a wide variety of substances, the process involving water is crucial to the environment and life, human. Condensation plays a vital role in Earth’s weather and climate, and is a vital part of the water cycle on the planet. We see visual evidence of the process in daily activities like taking a shower, driving a car in winter, or looking up in the air after a plane has passed by. In chemistry the word condensation also refers to the creation of a more complex molecule from smaller, simpler molecules with a loss of water.

Background

Condensation is a process that has been around as long as the elements have existed. However the ability to use condensation to perform important tasks is more recent. The creation of a steam engine that used the process of condensation was patented by Thomas Savery (1650–1715) in 1698. He built a machine to pump water out of mines, a labor that had previously been done using horses and wagons. The machine used a combination of heating and cooling water to create a vacuum that would pump the water from the bottom of the mine. The machine was referred to as both the Fire Engine and the Miner’s Friend and a patent was granted for the device. Thomas Newcomen (1663–1729) advanced Savery’s machine, but because of Savery’s patent, he was forced to work with first inventor. Newcomen’s advanced machine was called an Atmospheric Engine because the pressure involved was near atmospheric pressure. The machine was widely used for many years until the technology was further advanced by James Watt (1736–1819). Watt’s machine included a separate condenser and used substantially less energy to operate. More recently, Edward Linacre developed a piece of equipment that uses condensation to grab water from the air to irrigate fields in Australia. This innovative design won the 2011 James Dyson award.

Substances in gas form have their molecules further apart with greater amounts of movement relative to each other than if the substance is in liquid form. The temperature of the substance affects whether the substance is in liquid, gas, or solid form. The higher the temperature, the more likely it is to be in gas form. The highest temperature at which a substance changes from a gas to a liquid is referred to as its dew point. The amount of moisture in the air affects the dew point temperature, with condensation occurring more easily with greater humidity.

Impact

Condensation plays a integral role in the water cycle for our planet. The Earth’s water system depends on rainfall to help plants, animals, and humans live. Cloud formation is the result of condensation. Water vapor, or water in gaseous form, rises from the Earth from bodies of water, such as lakes, or from plants. When the water vapor rises from water sources, it is referred to as evaporation. Water vapor that arises from plants is referred to as transpiration. As the water vapor rises, it becomes cooler and expands. The water droplets attach to small particles, such as dust or dirt, to form clouds. These small dust or dirt particles are called condensation nuclei and are at the core of every water droplet in a cloud. When the cloud becomes large or heavy enough, it creates rain or snow, depending on the air temperature. This precipitation returns the water back down to Earth, completing the water cycle. Without condensation, we would not have this cycling of water, a vital element of life.

Fog is formed by the same condensation process that creates clouds, but at lower heights. Fog does not require the expansion of the water molecules due to elevation but it is created when the air temperature is a few degrees lower than the dew point. We often refer to the bathroom mirror after a hot shower as being "fogged up." This, too, is the result of condensation that is created due to the mirror being colder than the water vapor and thus attracting the water particles. Likewise, condensation forms the moisture on the outside of a cold glass of water.

Evidence of condensation can be seen in the sky after a jet flies overhead at a high elevation. The difference in temperature between the jet exhaust and the air the jet flies through is substantial enough to create condensation. The air at high elevation is cold enough that when the liquid water clings to particles (like when clouds are formed) it becomes frozen. The frozen trail remains, thus the creation of contrails. The word contrail comes from the combination of the words condensation and trail.

There are many situations when it is best to avoid condensation from occurring. The small packets of silica (or silicon dioxide) that are included with many electronic and other products are designed to pull any moisture from the air to avoid condensation from taking place. If condensation occurs in houses it can create moisture that leads to mold, which can be hazardous or render electronic appliances useless.

Bibliography

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Iwabuchi, Hironobu, et al. "Physical and Optical Properties of Persistent Contrails: Climatology and Interpretation." Journal of Geophysical Research: Atmospheres (1984–2012) 117.D6 (2012). Print.

Kandlikar, G. K. Handbook of Phase Change: Boiling and Condensation, CRC, 1999. Print.

Kubin, Milan, et al. "Experimental Analysis of Steam Condensation in Vertical Tube with Small Diameter." International Journal of Heat and Mass Transfer 94 (2016): 403–10. Print.

Lebrun, T., et al. "Thermal Evolution of an Early Magma Ocean in Interaction with the Atmosphere: Conditions for the Condensation of a Water Ocean." BIO Web of Conferences. Vol. 2. EDP Sciences, 2014. Print.

Wang, Pao K. Physics and Dynamics of Clouds and Precipitation. London: Cambridge UP, 2013. Print.