If dust can be knocked into stratosphere, it will fall very slowly because no water can condense on it.

tex2html_wrap84 dust falls at, tex2html_wrap85 cm/s doing a calculation similar to that of rain drops in fog. This gives a time scale of about 1 year.

Need to kick up, tex2html_wrap86 . Energy to lift dust is tex2html_wrap87 .

source psfile jl@crush.caltech.edu index