Next, we will examine band 6 - the emitted thermal band (10.5- 12.5 µm). Remember that the spatial resolution for this band is 4 times coarser - 120 m compared with 30 m - than the other bands. The effect of this reduced resolution is immediately evident in viewing the subscene in that many details discernible in the other bands tend to be "smeared" out in this one. Yet the main elements you have come to know from bands already scanned are still readily recognized.

In fact, the hilly terrain is even more like a 3-D rendition owing to the sharp contrast between the hotter sun-facing slopes and the back-facing slopes that are sufficiently cooler to appear now as fairly uniform dark shadow-patterns. This gives a superior sense of topographic relief to this part of the scene and also brings out the valley regions. Some tones favoring medium gray, as at v, represent the cooling effects of grass ground cover. An extremely bright, but isolated, spot at h coincides with Morro Rock which, being a bare rock surface with steep slopes, absorbs solar radiation and heats up so that it becomes a significant emitter of thermal energy. The towns labeled in yellow have moderate gray levels, indicating they are somewhat cooler than the natural hillsides but several lighter tones within them are located in the downtown areas which are customarily rather warmer than residential areas (that have lawns and more trees).

Water, which has a notably higher heat capacity than most "dry" materials found on land, nevertheless in daytime thermal IR images tends to be cooler than most lighter land surfaces that are directly heated. (Section 9, dealing with thermal imagery, reviews the principles governing the tonal displays of features at different radiant temperatures.) That is evident in this image in which the ocean and the bay both have moderately dark gray levels. If this image had been taken at night, the water would be expressed in much lighter tones than the neighboring land because it has retained much of its internal heat whereas the land has radiated its absorbed solar energy thereby losing heat and cooling to radiant temperatures lower than water. An uneven pattern of bands of slightly lighter gray levels as seen in the Pacific Ocean is not "real" here but is a noise-like artifact associated with the sensor response. There is one pattern that is both anomalous and meaningful. In the water just north and west of Morro Rock is an irregular pattern with a lighter tone that jets out like a plume of sediment entering the ocean from the shore. This is precisely what is expected from the nearby power plant (at t) which dumps its thermally heated waste water into a nearby body of standing water.

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