Sastrugi
 
Snow surface on the Antarctic ice sheet shows various patterns carved by winds. A pattern called sastrugi forms a few 10cm-1m high uneven waves along wind direction. The inland snow field in Antarctica is not flat due to this sastrugi.
Sastrugi is an important indicator for analyzing prevailing wind direction and its changes.
 
  Source: Nankyoku kagakukan. National Institute of Polar Research. 1990.