 Detection of low clouds and fog using infrared imagery can sometimes be tricky at night and early in the morning because one of the main assumptions that forecasters use when interpreting infrared images, that temperatures decrease with increasing height, isn't always true. Take this enhanced infrared image as an example. Assuming that temperatures decrease with increasing height might lead us to believe that this dark area has clear skies, meaning that the satellite is seeing emissions from relatively warm ground, while the lighter shaded areas, which are colder, represent cloud cover. But that's not the case at all. The brighter gray shaded areas actually have clear skies. And they appear colder on this enhanced infrared image because the ground is colder than the tops of the low clouds and fog in this area. For the record, these very brightly colored areas actually do represent very cold cloud tops, which are high in the troposphere. Difficulty in discerning between low clouds or fog and clear skies on enhanced infrared imagery at night or early in the morning isn't all that uncommon because the tops of low clouds can be warmer or have similar temperatures to the ground in surrounding areas with clear skies. But using multiple wavelengths of the electromagnetic spectrum gives forecasters another tool for more easily identifying low clouds or fog at night. This image was created by using multiple wavelengths from the infrared portion of the electromagnetic spectrum, differencing their contributions in order to better identify cloud thickness, composition, and temperature, and then applying different colors. Using this approach causes low clouds and fog to appear much more intuitively. We can see the area of low clouds across southeast Texas over into Louisiana and Arkansas in this whitish tan shading. The really high clouds to the northwest here now appear very dark while the slice of cold ground in between appears pink. Finally, once the sun rose on this particular day, traditional visible imagery confirmed our interpretation of the multi-channel approach with a thick area of low clouds and fog surrounded by clear skies. So the multi-channel approach at night really made the interpretation of low clouds and fog much more intuitive compared to traditional infrared imagery.