Today we had the last eclipse of the Spring 2012 Eclipse Season. Here are 4 images of the Sun at about 0630 UT today. Comparing the upper left image (1600) with the upper right and lower left we see the different ways the Earth's atmosphere absorbs light from the Sun. Ultraviolet light at 1600 Å is absorbed about 105 km above the surface of the Earth while 193 is absorbed at 130 km and 304 at 150 km. (171 is absorbed at 120 km). The 1600 edge is pretty straight while the others are rougher. Changes across the disk of the Sun are important in the other three channels, but the effects of changes in the Earth's atmosphere at 150 km can be seen at the top of the 304 image.
To really see the effects of the Earth's atmosphere you should use difference images. If all of the solar patterns can be determined you can map the Earth's thermosphere with these partial occultations.
Next on the schedule is a ΔV burn today at 2315 UTC (7:15 pm ET).