Image of the Day: Striking Sunset from Sun Pillar
One of the biggest open questions about climate change is whether clouds will slow or speed global warming. Everyone agrees that as the globe warms, more water vapor will enter the atmosphere. If that leads to more low-level cumulus clouds — the kind that bring rainstorms — they'll provide more shade, and block out some of the Sun's warming effect. If it leads to more cirrus clouds, however — the thin, high-altitude clouds shown in this image — they'll trap extra heat, and make the warming more intense.
Credit: Kevin Povenz/flickr