Dark Skies Africa

Cloudy Skies

Standard Gaussian-type statistics are not really adequate to describe atmospheric variability; this traditional approach implicitly dismisses fluctuations as "noise" of use only in computing a standard deviation which, together with the mean, presumably varies so little in space and time that one can meaningfully speak of "climatological" values. In geophysics, unfortunately, this approach ofte...

Geoengineering: Whiter skies?

[1] One proposed side effect of geoengineering with stratospheric sulfate aerosols is sky whitening during the day and afterglows near sunset, as is seen after large volcanic eruptions. Sulfate aerosols in the stratosphere would increase diffuse light received at the surface, but with a non-uniform spectral distribution. We use a radiative transfer model to calculate spectral irradiance for ide...

Blue skies for the best people.

DOI: 10.1161/CIRCRESAHA.114.305403 1 Editor’s preamble: The criteria for awarding research grants are a topic of the utmost importance, one that needs to be examined and debated carefully. As the readers probably know, there are strong and disparate viewpoints regarding this problem. Accordingly, in line with our editorial vision (1), this issue of Circulation Research features a News &Views co...

Observed brightness distributions in overcast skies.

Beneath most overcasts, clouds' motions and rapidly changing optical depths complicate mapping their angular distributions of luminance L(v) and visible-wavelength radiance L. Fisheye images of overcast skies taken with a radiometer-calibrated digital camera provide a useful new approach to solving this problem. Maps calculated from time-averaged images of individual overcasts not only show the...

Flying the smoky skies: secondhand smoke