Humidity is the concentration of moisture present in the air, and regardless of what industry or business you are in, problems stemming from undesirable humidity can have an adverse effect on your production output and business. In this blog post we take an in-depth look at how humidity is measured and its importance for business owners.

How do you measure humidity?

Humidity can be measured in two ways:

  1. Absolute humidity is the amount of moisture present in a particular volume of air and is typically measured in g/kg.
  2. Relative humidity (RH) is the relationship between the actual amount of moisture present and the maximum amount the air could contain. This is always measured as a percentage.

Warm air can carry more moisture than cold air - the warmer the air, the higher the relative humidity (RH) because warm air contains more energy to evaporate water into vapor and then keep it as vapor.

When talking about humidity, it is also important to consider the dew point. The dew point is when the relative humidity has reached 100% and the air cannot hold more water vapor, at this point the vapor starts to condense.

The Mollier diagram is a helpful tool for understanding the relationship between air temperature and moisture content in a thermodynamic system and is a core element of our daily work at Cotes.


calculating the relative humidity

The Mollier Diagram describes how air changes state depending on how cool or warm it is. In order to optimise the industrial processes and commercial operations of your business, it is important to understand the relationship between humidity, temperature and moisture content. If you know the temperature and the moisture content you can calculate the relative humidity of an area. Once you know this you can monitor and adjust for optimal conditions.

Legend has it, that the Mollier Diagram was first inspired when Richard Mollier, a professor of Applied Physics and Mechanics and a pioneer of experimental research in thermodynamics in the late 19th century Germany, was in a café and heard about a homicide in a neighbouring village. He had the idea that he could solve the case by developing a chart with the thermodynamic suspects. [Of course, creating the actual Mollier Diagram took much longer - years of researching the thermodynamic properties of various media and plotting those quantities in charts and diagrams.]

Eventually, the Mollier diagram was born - the diagram provides a graphic representation of the relationship between the physical conditions and corresponding changes in a system: the two can be linked by plotting lines on the diagram and figuring out what their intersections represent.

mollierdiagram (1)-1

Download the Mollier Diagram here.



Do you see or experience:

  • Electrical faults?

  • Corrosion?

  • Mould and/or listeria contamination?

  • Product quality issues?

  • Long drying times or loss of production?

Tell us about your humidity issue