A Three-Layer Model

This post is part of a primer on infrared spectroscopy and global warming. The previous post introduces a two-layer model  and is a necessary prerequisite to understanding this post.  In this post I start with the following assumptions.  There is a source of infrared radiance that has emissivity of 1, i.e., it radiates as a perfect blackbody at a temperature of  288 K.  The radiance from that layer is I₀

There is a layer of air 1000 m thick with 380 ppm carbon dioxide at a temperature of 278 K.  There is another layer of air 1000 m thick with 380 ppm carbon dioxide at 268 K.  All layers are at a constant pressure of one atmosphere.

A Two-Layer Model

This post is part of a primer on infrared spectroscopy and global warming. The previous post discusses the issue of saturation in the 14-micron band of carbon dioxide in a single-layer model.   The post before that discusses Beer's Law, and is a necessary prerequisite to understanding this post.  This post starts to look beyond the single-layer model, by discussing a two-layer model, and beginning a discussion of radiative transfer.

A Note On Saturation of the Carbon Dioxide 15-micron Band

This post is part of a primer on infrared spectroscopy and global warming. The previous post discusses Beer's Law, and is a necessary prerequisite to understanding this post.  The previous post also introduced the idea of saturation of a single layer model.  This post looks more deeply at the single-layer model and the saturation of the 15-micron band of carbon dioxide.

Infrared Spectra of Molecules of Interest

This post is part of a primer on infrared spectroscopy and global warming. The previous post concludes a three-post series that looks at molecules and radiation and discusses how molecules give rise to infrared spectra.  This post discusses the infrared spectra of some molecules of interest.

 Figure Source

Molecules and Radiation III: Vibration, Dipoles, and Ro-Vibrational Spectra

This post is part of a primer on infrared spectroscopy and global warming. The previous post looked at the vibrational modes of several molecules including HCl and several molecules of atmospheric interest. This post discusses how these modes relate to infrared absorption and uses HCl as an example.

OPINION: Don't Call Climate Doubters Deniers

I am friendly with  and love people who doubt the reality of climate change.  The same cannot be said for those who "doubt" the reality of the Final Solution.  Lately it has become commonplace to refer to the former as "deniers," but the implicit connection to the latter offends me.  To understand why, I think it is useful to look at these groups of people.

Molecules and Radiation II: Molecular Vibration, Rotation, and Translation

This post is part of a primer on infrared spectroscopy and global warming. The previous post  starts the process of looking at the interaction between infrared radiation and molecules and discusses the degrees of freedom of molecules and the Born-Oppenheimer approximation.  The result of the previous post is that for the purposes of IR spectroscopy, one can focus on the motion of the atomic nuclei and separate them from the electronic degrees of freedom of a molecule.

Figure Source

There are 3N nuclear degrees of freedom for a molecule that has N nuclei.  For the HCl molecule that means there are 6 degrees of freedom.