Click on the image above to download the associated VIS loop images.
In the 10.7 um band such landmarks appear as small, warmer segments within the cooler areas since snow cover is usually colder than nearby snow-free areas. This same snow-covered region will appear black in the day-time 3.9 um imagery due to its poor reflectivity, with the warmer lake and river areas having distinct shapes.
Mid- or upper-level cloud can be detected over snowfields when landmarks become obscured as high clouds move across them, and/or by the cloud-to-underlying- snow temperature differences. Imagery at 6.7 um will also show cirrus, but not the ground. Observe the 10.7 um imagery over northeast OK and southeast MO for an example of upper-level cloud versus snow discrimination.
Prior to GOES-8, it was difficult to identify low clouds over snow. VIS imagery typically shows little difference between snow and low cloud or fog, while at 10.7 um they often are nearly the same temperature. Day-time 3.9 um imagery, distinguishes low cloudiness and fog from snow, due to reflectivity differences.
