In gallery: Photos of the month (2003)
Related photos: Clouds
Various cloud forms
Smog is a mixture of humid air ("fog") and pollution ("smoke"). You can usually see smog as a brownish layer blanketing major cities. The photo shows smog and haze over Rio de Janeiro, Brazil. The sky actually appears very clear here for a metropolitan area so close to the sea.
Photo taken in Rio de Janeiro (Brazil) on December 16 using Nikon FE with 50mm lens at f/5.6; Fuji Provia 100-F.