Power plant plumes
The AWIPS image of MODIS 11.0µm-3.7µm “fog/stratus product” (above) reveals several long plumes embedded within the extensive stratus cloud deck (yellow to red enhancement) that covered much of northern and central Minnesota during the pre-dawn hours on 19 October. These plumes likely originated at large coal-fired power plants (or paper mills?) located across that region — emissions from these industrial sources may have acted as cloud condensation nuclei, causing a higher concentration of smaller supercooled cloud droplets downwind of the plants.
The MODIS Cloud Phase product (below, lower left panel) showed that this stratus deck was primarily a water-phase cloud (blue enhancement); MODIS 11.0µm IR window channel brightness temperatures were generally around -14 C across that region, indicating that the stratus cloud was composed of supercooled water droplets. Note that these power plant plumes were not evident on the 4 km resolution GOES fog/stratus product (below, upper right panel). The GOES sounder Cloud Top Height values were around 11-12 kft over the area.
