![]() Normally, when people talk about humidity, they’re referring to ‘relative humidity’, which is a percentage of the amount of water vapor in a volume of air compared to the maximum amount of water vapor that could be in that same volume of air at a given temperature. ![]() To understand condensation, we first need to understand humidity. You don’t always have dew on your grass in the morning, for example.īut what are these conditions? Hold onto your hat, it’s about to get technical! We’re going to dive into psychrometrics, which is the study of the properties of gas-vapor mixtures. You may have noticed that in our examples of condensation above, the conditions have to be just right for condensation to form. This phase change is caused by a temperature decrease, usually in the presence of a solid material onto which the droplets form (the grass, drinking glass, and bathroom mirror in our examples). If you’re ever seen early morning dew on your grass, noticed water droplets form on the outside of a cold drinking glass, or found your bathroom mirror covered in ‘fog’ after a hot shower, you’ve experienced condensation.Ĭondensation refers to water in its gaseous form (known as water vapor) that changes phase into a liquid (in the form of water droplets). So let’s start with building a solid foundation of knowledge, then we’ll jump into condensation effects and prevention. There are companies out there happy to take your money for products that don’t work, and people whose well-meaning but incorrect advice will steer you in the wrong direction. It may seem a bit boring at first to learn all science about condensation, but we think it’s important for you to understand the “why” behind the “what”. We’ll teach you how condensation forms, why it is a relevant concern for shipping container homes, what the effects of condensation can be for container homes, and finally how you can stop the condensation. It’s a technical topic that can be confusing, but our intention is to pull back the curtain of mystery that surrounds it. It can even go by a few names, like container rain, container sweating, wall moisture, and others. ![]() And now a paradoxical question: which of those two situations would feel more humid? Definitely the second one! The dew point is the value we should look at if we want to know how dry or humid it is outside, not the relative humidity.If you’ve done any research into shipping container homes, you know that condensation is a common concern for a lot of people.The dew point is 60 ☏ (~15.5 ☌), so following the formula, we can find out that the relative humidity is ~60%. Let's take another example: summer finally has come, we are relaxing near a river, and the temperature is 75 ☏ (24 ☌).Our forecast shows that the dew point is equal to 40 ☏ as well – so the relative humidity is 100%. Imagine that it's a cold autumn morning, 40 ☏ outside (~4.5 ☌).To better understand the difference between dew point and humidity, let's look at this example: In a particular case, when the air is maximally saturated with water (the relative humidity is 100%), the dew point is equal to the current temperature. Relative humidity is a more confusing value as it depends on temperature and the pressure of the system in question.ĭew point and relative humidity are not the same, but they are closely related: the higher relative humidity is, the closer the dew point is to the current air temperature. If you want to know whether (or weather, heh) it's comfortable or not to have a morning jog or go on a weekend hiking trip – stick with that term. The higher the dew point is, the more moisture that is in the air. Now that you know the formulas for dew point and humidity, you may wonder, what is the difference between those two terms?ĭew point is an accurate measurement of the moisture content in the air. It is merely the water content in the air, expressed in grams per cubic meter:Ībsolute humidity = m / V, where m is the mass of water vapor, and V is the volume of the air and water vapor mixture.įor saturated air at 30 ☌ (86 ☏), the absolute humidity in the atmosphere ranges from ~0 to 30 grams per cubic meter.ĭid you notice that the formulas don't take the temperature into consideration? To understand this definition, you also need to know the meaning of absolute humidity. Or, expressed differently, the relative humidity is the ratio of the water vapor pressure Pw to the saturation water vapor pressure Pws at the given temperature: Relative humidity = 100% × current absolute humidity / max absolute humidity In other words, it's the amount of moisture in the air compared to what the air can maximally "hold" at that temperature: It is the ratio of the current absolute humidity to the maximum absolute humidity possible for the current temperature. Relative humidity is expressed as a percentage.
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