Refractive index of humid air in the infrared: model fits

2006/10/31 by Richard J. Mathar
Chemistry · Engineering · Physics and Astronomy · #Advanced Measurement and Metrology Techniques #Calibration and Measurement Techniques #Spectroscopy and Laser Applications #physics.optics

paper · pdf · doi:10.1088/1464-4258/9/5/008

published as J. Opt. A: Pure Appl. Opt. 9 (5) (2007) 470-476 · Corrected exponents of c0ref, c1ref and c1p in Table I

arxiv created 2007/02/02 · openalex publication_date 2007/04/24 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

The theory of summation of electromagnetic line transitions is used to tabulate the Taylor expansion of the refractive index of humid air over the basic independent parameters (temperature, pressure, humidity, wavelength) in five separate infrared regions from the H to the Q band at a fixed percentage of Carbon Dioxide. These are least-squares fits to raw, highly resolved spectra for a set of temperatures from 10 to 25 C, a set of pressures from 500 to 1023 hPa, and a set of relative humidities from 5 to 60%. These choices reflect the prospective application to characterize ambient air at mountain altitudes of astronomical telescopes.

Citations

• Measurement of the refractive index of air and comparison with modified Edl n's formulae
• The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use
• The Spectrum of Molecular Oxygen
• Thermodynamic Properties of Air and Mixtures of Nitrogen, Argon, and Oxygen From 60 to 2000 K at Pressures to 2000 MPa