Hold any mouse button down as you move the cursor over large 0.65 micron visible image. The smaller inset window shows the 6.7 micron IR (water vapor) image from the same time (25 March 1998, 21:30 UTC).

Note how the areal extent of the visible wave clouds over parts of Colorado and New Mexico is much less than that of the mountain waves apparent on the water vapor image. If the atmosphere is dry, the upward motions within the mountain waves is insufficient to lift the air parcels to their condensation level (hence no visible clouds).