The GOES reflectivity product is generated by taking the difference of the radiance values of the 10.7 µm channel from the the 3.9 µm channel values, which contain both emitted and reflected components. It is generally used in daylight situations to discriminate between liquid and ice particles. Glaciated clouds and snow appear dark, while fog and other low-level liquid clouds appear light. As suggested in the discussion of the fog product, more information can be found about this application in the CIRA-RAMM Team's GOES Advanced Imagery Applications Tutorial
The reflectivity product image below has four interesting features: a large area of cirrus in eastern MT and WY (labeled Ci), an area of fog in southern CA, glaciating convective tops in NM and a region of stratus in KS and OK (labeled St). When viewing the loop, notice the dissipation of the CA fog, the development of convection in NM, and the northwesterly movement of the Ci in MT.
