1. Emissivity of Different Minerals: Example

2. Emissivity of Water Vapor, Normal Incidence
Note: Strong spectral dependence of emissivity due to rotational and vibrational absorption bands.

3. Normal Emissivity of a Liquid Water Layer
Notes: Only need about 1mm thickness to be opaque.
Strong spectral dependence of gaseous phase washed out.

4. Angle Dependence of Emissivity
Message: Even something so strongly absorbing as water (IR) has high reflectivity (low emissivity) at grazing angles.