Mars clouds seen on a winter afternoon by Opportunity on Sol 956 (October 2, 2006). (NASA/JPL/Texas A&M/Cornell image)
A group of French and Russian scientists using data from the SPICAM ultraviolet and infrared spectrometer on the Mars Express orbiter has discovered that the dust particles in the planet’s atmosphere occur in two sizes; their results are published in the journal Icarus….
The scientists found the larger size has both H2O ice grains with an average radius of 1.2 micrometers and slightly smaller dust particles (radius = 0.7 micrometers). The smaller size has a radius of 0.04 to 0.07 micrometers… [One micrometer is about 1/25,000 of an inch.]
The findings are important because, according to the scientists, aerosols play a key role in forming the planet’s climate. Because of fine dust particles in the higher layers of the atmosphere, ice “embryos” are formed faster, which, in turn, influences the build-up of clouds. The clouds are responsible for both precipitation and temperature conditions on the planet’s surface. Analyzing the way the dust is spread in the atmosphere of the planet with regard to the altitude and geographical coordinates is crucial for forming the full picture of what is happening on Mars… [More at links]