light air

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A wind with a speed of from 1 to 3 knots (1.15 to 3.5 miles per hour; 1.9 to 5.6 kilometers per hour), according to the Beaufort scale.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun meteorology, nautical A light wind with wind speed between 0,3 and 1,5 m/s; a Force 1 wind strength on the Beaufort scale.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun wind moving 1-3 knots; 1 on the Beaufort scale