Senior Airman Austin Clayton, 28th Operations Support Squadron air traffic control journeyman, sketches a prevailing visibility observation graph at Ellsworth Air Force Base, S.D., Jan. 7, 2016. Weather can affect flight conditions and visibility, which makes directing aircraft more difficult. Ellsworth’s tower covers five nautical miles, making visibility observations important to mission success. (U.S. Air Force photo illustration by Airman 1st Class James L. Miller/Released)