Water Vapor

Many of us take water vapor for granted. After all, it represents a portion of our daily lives. Water vapor is used within humidifiers, it is emitted in the form of steam when boiling a cup of tea and it appears as fluffy clouds floating overhead.

However, water vapor also plays a handful of crucial roles in terms of climate change and it can have a massive impact upon specific industries such as the oil and gas sector. This is why it is important to take a closer look at vapor water as well as its direct (and indirect) influences. We have compiled a wealth of interesting information that is highlighted immediately below.

What Exactly is Water Vapor?

Water vapor is nothing more than water that exists in a gaseous as opposed to liquid state. Note that this vapor is still chemically equivalent to water (H2O). However, the molecules are spread further apart and they are moving at a much faster rate. This signifies that they will not interact with one another as readily when found in water or water-ice.[1]

It is also important to make an additional observation. While clouds are often thought of as water vapor, this is not entirely true. Clouds, fog and mist are suspended droplets of liquid water in the air.[2] Water vapor is actually invisible to the naked eye. To answer this question, we need to take a closer look at the differences between suspended water particles and water vapor.

Floating Particles Versus Water Vapor

As mentioned previously, water vaporizing (such as when reaching its boiling point under the normal vapor pressure of water) will release small droplets into the air. Although these are often termed "water vapor", what we are actually seeing is the particles themselves suspended by nearby vapor. The same holds true when referring to the process of evaporation.

As the particles rise and subsequently condense to perform clouds, they are essentially embedded in a "matrix" of water vapor. Simply stated, we cannot see water vapor in its purest form. We instead note the particles of water which denote its presence.[2]

What Role Does Water Vapor Play in Specific Industries?

While often present "behind closed doors", water vapor plays a crucial role in many different industries. One application involves its use as a gas when lifting airships into the sky. As water vapor is less dense than air (5.98 × 10⁴ g cm³), it will cause objects of a relatively low weight to float when placed within an enclosed environment.[3]

Another well-known use involves the production of steam. Steam engines have existed for hundreds of years and it can be argued that these inventions ushered in the subsequent Industrial Revolution. Now that we can appreciate the relationship between steam and water pressure, it is clear to see why this invisible gas is so crucial.

Finally, water pressure is an important variable that needs to be taken into account within the petrochemical industry. Water vapor is present within natural gas. If allowed to accumulate, it can corrode equipment, block pipelines and even cause production to grind to a halt.[4] This is why a process known as "gas dehydration" represents a critical portion of the refinement process. A type of measurement technology known as a hygrometer will often be used to calculate water vapor concentrations within natural gas.

Water Vapor and Climate Change: What is the Relationship?

Many of us associate climate change with the production of carbon dioxide alongside other greenhouse gases such as chlorofluorocarbons (CFCs). However, water plays a surprisingly crucial role. This is partially due to the specific heat of water vapor.

Water vapor is known for having a relatively high specific heat capacity. This is another way of saying that it will chemically absorb a significant amount of heat before it actually begins to increase in temperature. This is both a good and a bad thing.

As water takes longer to heat up and cool down, cities located close to oceans and lakes will often enjoy more steady temperatures when compared to those found inland. In the same respect, aquatic animals can enjoy a relatively predictable maritime environment with few instances of sudden temperature changes.

However, water vapor in the atmosphere can also contribute to the greenhouse effect. Studies have shown that this substance is responsible for approximately 50 per cent of the global warming that mankind is currently experiencing. This leads us directly into the next subsection.[5]

How does the presence of water vapor impact climate change?

In order to fully answer this question, we first need to appreciate the global "water cycle". The climate change specialists at NASA have outlined the process as follows:[6]

  • Greenhouse gases are released into the atmosphere.
  • Surface temperatures begin to rise.
  • This causes more water to evaporate in the form of water vapor.
  • The water vapor absorbs heat radiated from the surface; preventing it from escaping from the atmosphere.
  • As a result, temperatures once again begin to rise.

Let’s also remember that the density of water vapor is less than air. Thus, this vapor will rise into the atmosphere where it remains suspended before the associated droplets condense, form clouds and then fall to earth. This results in what is sometimes termed a "positive feedback loop". As more water vapor is released, it will retain more heat. This causes even more to evaporate and so on.

Why is the Presence of Water Vapor not Taken as Seriously as Other Greenhouse Gases?

This is actually a very important question that warrants additional attention. We have already seen that water vapor is responsible for roughly half of the global warming that mankind has already experienced. If this is the case, why are we not taking measures to mitigate its release?

The simple fact of the matter is that most forms of water vapor are produced by completely natural processes (such as evaporation). It is therefore nearly impossible to control. Furthermore, limiting the amount of water vapor in the atmosphere would also reduce global precipitation levels; impacting the very survival of plants and animals alike.[7]

Having said this, there is a correlation between carbon dioxide levels and water vapor concentrations due to the positive feedback loop explained earlier. It therefore stands to reason that if greenhouse gas emissions are controlled, less vapor will be released into the environment (helping to slow down climate change over time).

Water Vapor – A Part of Life

Water is absolutely essential for life and it plays just as important of a role in its gaseous state. We can also see that water vapor offers numerous benefits and applications within modern society. While it does indeed have an effect upon climate change, there are many other factors to be taken into account.