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Proceedings Paper

Infrared- And Millimeter-Wavelength Absorption In The Atmospheric Windows By Water Vapor And Nitrogen: Measurements And Models
Author(s): Michael E Thomas
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Paper Abstract

Attenuation of electromagnetic waves by atmospheric gases is an im-portant consideration in a variety of radar and electro-optical applica-tions. Molecular absorption by strong bands of H2O and CO2 defines the atmospheric window regions. The window regions are not totally transparent and feature weak line absorption and continuum absorption. The experimental character of continuum absorption by water vapor in atmospheric window regions at millimeter wavelengths and 10, 4, and 2.2 Am and nitrogen at 4 μm is surveyed. This includes recent measurements at The Johns Hopkins University Applied Physics Laboratory on H2O at 2.2 μm and the nitrogen collisioninduced band at 4.3 μm. Also, some of the concepts and models used to characterize these phenomena will be reviewed. The search for a unified theory on the water vapor continuum has been elusive, yet the frequency and pressure dependence is consistent with current far-wing theories. The temperature dependence is not totally understood. A model describing the temperature dependence of the nitrogen continuum is emphasized.

Paper Details

Date Published: 10 August 1988
PDF: 7 pages
Proc. SPIE 0926, Optical, Infrared, Millimeter Wave Propagation Engineering, (10 August 1988); doi: 10.1117/12.945764
Show Author Affiliations
Michael E Thomas, The Johns Hopkins University Applied Physics Laboratory (United States)

Published in SPIE Proceedings Vol. 0926:
Optical, Infrared, Millimeter Wave Propagation Engineering
Norman S. Kopeika; Walter B. Miller, Editor(s)

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