Infrared Satellite Interpretation
October 11, 2004
This infrared satellite image from the NOAA GOES-12 satellite shows a grayish-white shading over a large portion of the upper Middle West at 1115 UTC (6:15 a.m. Central Daylight Time) on September 28, 2004. At first glance, you might think that clouds covered most of the region, but sky conditions were generally clear, as supported by a gaggle of early morning temperatures in the 30's (map above). So, for the most part, you're looking at cold ground. You can get a sense of the clear sky conditions when you notice the dark, sinuous outline of the Missouri River in South Dakota (other bodies of water, like lakes in Minnesota, also appear dark). Bodies of water cool more slowly than the land during autumn, so the Missouri is warmer than the cold ground surrounding it. Thus, on cold, clear mornings in early fall, the dark outlines of warm bodies of water that are surrounded by cold ground tend to stand out on conventional infrared satellite imagery.