how dust dul storms storm start dust storms are generated by the same air mechanics that build the beautiful leecy fleecy cumulus clouds of I 1 the middle strata of the atmosphere 1 science service explains when the sun has been shining strongly on the earth for some time a considerable sid erable miss mass of air la Is warmed and since warm air Is less dense than cold air it begins to rise sometimes nearly vertically it if there is plenty of moisture in the soil and vegetation these rising air currents carry up water vapor which on cooling in the upper levels condenses into clouds if however there has been a drought of several weeks duration as frequently happens in the west in late autumn and early spring a dust storm results