a sheet of lightweight paper, bearing an official postal stamp imprint, that is folded to form its own envelope and can be sent via airmail at a special, low rate because of its standard size, light weight, and lack of enclosures.
the study of the air or atmosphere. noun (archaic) the description of the character of the upper atmosphere
of, relating to, or based on an aerial survey of the earth’s : an aeromagnetic map.
the branch of meteorology involving the observation of the atmosphere by means of balloons, airplanes, etc. (in former use by the U.S. Navy) meteorology. noun the study of the atmosphere, particularly its upper layers aerology (â-rŏl’ə-jē) The branch of meteorology that studies the total vertical extent of the Earth’s atmosphere as opposed to the atmosphere […]
the science of measuring magnetic characteristics associated with atmospheric conditions of the earth. aeromagnetics (âr’ō-māg-nět’ĭks) The scientific study of the Earth’s magnetic characteristics as measured from the air.