Field observations and experimental research in the sands of the South-East Kara Kum have shown that with the sum of velocities of active winds being equal, the rate of movement of the barchan chain’s crest is two times as high when its surface is wet as when it is dry. At the same time, the structure of a wind-sand stream and the character of movement of eolian forms in the wet period of a year sharply differs from their dyna­mics in the dry period.