N04: Introduction to Humidity and Trace Moisture Measurement – Full Day
- Start Date : 3 February, 2026
- Start Time : 8:00am
- End Date : 3 February, 2026
- End Time : 5:00pm
- Address : Harbor Rm, N Tower
No Schedule
Abstract
Humidity is not a single quantity but a family of quantities that involve moisture content in a gas, including relative humidity, dew point, water amount fraction, and water mass ratio. This course will teach the fundamentals of these quantities and explain how they relate to each other and are influenced by other quantities, such as temperature and pressure. Applications requiring accurate measurement and/or control of humidity will be discussed. We will also describe the different types of instruments used to measure quantities in the humidity family, including chilled mirror hygrometers (dew point), capacitance sensors (relative humidity), psychrometers (relative humidity), and cavity ringdown spectrometers (water amount fraction). Finally, the course will discuss humidity generators and how they can be used as primary standards for water amount fraction and dew point for calibration of hygrometers. It will show how a humidity generator can be combined with a temperature-controlled chamber to make it a primary standard for calibration of relative humidity sensors. The NIST primary standard humidity generator will be fully described as an example of the type of generators found in National Metrology Institutes.
contact: Christopher Meyer, Christopher.meyer@nist.gov
Chris Meyer
Chris Meyer has 30 years of metrology experience working at NIST, working in the areas of temperature, humidity, and pressure standards. He is an honor graduate of Haverford College and received his Ph.D. in physics from the University of California at Santa Barbara. Afterwards, Chris came to NIST as a postdoc, where he and performed acoustic thermometry to obtain some of the most accurate thermodynamic temperature measurements ever made over the range 234 K to 303 K. He joined the NIST Thermometry Group (Now the Thermodynamic Metrology Group) in 1991. Chris’s first project in this group was to construct a facility to realize the International Temperature Scale of 1990 (ITS-90) over the low-temperature region (0.65 K to 84 K) using 3He and 4He vapor-pressure thermometry, gas thermometry, and platinum resistance thermometry. Since that time, he has worked in several other areas of thermometry, including wire thermocouples, digital thermometers, light-pipe radiation thermometers, and fluorescence thermometers. Chris has worked in the discipline of humidity since 2000. During this time, he helped develop the current NIST gravimetric hygrometer and the hybrid humidity generator (the US national standard for humidity). He used the gravimetric hygrometer to validate the performance of hybrid humidity generator and measure thermophysical properties of moist air and moist CO2). Chris has operated the humidity calibration laboratory since 2013. Recently, he spent 15 months working at the International Bureau of Weights and Measures (BIPM), helping develop a manometric system for determination of the amount fraction of CO2 in air. In 2017 Chris entered pressure metrology and he now oversees the NIST piston gauge calibration laboratory.