DUST MAKES ICE GO AWAY. This multi-year plot made using TES data shows an anti-correlation: When the atmosphere becomes dustier (reddish colors, top panel), the amount of water-ice cloudiness (purple color, third panel) dwindles. Also note the year-to-year variations. Click on the image to download a larger version. NASA/JPL/Arizona State University
References:
Pearl, J. C., M. D. Smith, B. J. Conrath, J. L. Bandfield, and P. R. Christensen, Observations of water-ice clouds by the Mars Global Surveyor Thermal Emission Spectrometer experiment: The first martian year, J. Geophys. Res., 12,325-312,338, 2001.
Smith, M. D., The annual cycle of water vapor on Mars as observed by the Thermal Emission Spectrometer, J. Geophys. Res., 197, 5115, doi:5110.1029/2001JE001522, 2002.