Imager product is an infrared channel difference similar to, but computed differently than, the original CIRA fire product. This product may better show fires in the morning and evening due to image enhancements.
Hot spots appear white, as do low-level clouds.
More persistent and larger fires result in more continuous white spots. Clouds are generally distinguished from hot spots by their larger size and by their motion in an image loop. This is done using the same formula day or night, whether or not there is reflected solar radiation. Since the surface albedo and emissivity are inversely related, areas that reflect solar radiation during the day are actually areas with lower emissivity or a radiance deficit, compared to the longwave IR channel, at night. The solar zenith angle at every image pixel is used to generate a normalized albedo, independent of sun angle.