As just discussed, the fog product can be used to distinguish cloud phase at night. A multispectral image, called
the reflectivity product, can do the same during the day. This product also uses 3.9 and 10.7 um images. Daytime 3.9 um radiation received by the satellite is a combination of earth-emitted and solar-reflected components. The 10.7 um signal contains only earth-emitted radiation. The 10.7 um information is used to remove the 3.9 um emitted
component, leaving only that which has been reflected by the sun. Because liquid water clouds are more reflective than ice clouds at 3.9 um, this product may be used for daytime cloud phase determination. A more complete
description of the reflectivity product and its applications may be found in the RAMM Teams's 3.9 um tutorial. (Make sure you "bookmark" this location if you wish to return here from the tutorial!)
With the enhancement shown, the reflectivity product displays liquid water clouds as bright, and clouds comprised of
ice crystals as dark. Cloud phase differentiation is important since lightning will not be present unless glaciation has
If you came to this page from the "Sub-synoptic-scale IR (3.9 um) Imagery" presentation, and wish to return there, click here.