Infrared Radiation is measured atop the meteorological mast at the shore laboratory using an Eppley Model PIR (Precision Infrared Radiometer or Pyrgeometer). Most of the terrestrial infrared, or long-wave, radiation is contained in the region from 3.5 to 50 µm. The PSP using a a silicon dome that limits the transmission of radiation to this range of wavelengths. The PIR uses a thermopile and thermisters with the technique described by Fairall et al. (J. Atmos. Oceanic Technol., 15, 1229-1242) to to compute the total watts per square meter of downwelling infrared radiation. Variability in the downwelling IR radiation is driven changes in atmospheric temperature and humidity as well as the absence or presence of clouds.