Clouds' effect clear as cloudy day.(Science Update)

Our understanding of clouds and how they affect climate change is gray at best ... and unlikely to "clear up" anytime soon. But researchers continue to add to the body of knowledge regarding this complex topic. A recent study published in Nature ("The Impact of Humidity Above Stratiform Clouds on Indirect Aerosol Climate Forcing," 30 December 2004, Vol. 432, No. 23, p. 1014-1017) by Andrew Ackerman et al. reports that the humidity of the overlying air layer is a key player in determining the nature of clouds formed and their energy reflecting or trapping properties.

Aerosols in the atmosphere can have many potential effects on climate. Directly, there are particles …