THE IONIZATION OF THE ATMOSPHERE MEASURED FROM FLYING AIRCRAFT
The Gerdian type of atmospheric ionization measuring apparatus was attached to a cabin aeroplane so that the state of ionization of the atmosphere could be studied. The limitations of the apparatus for aeroplane use are discussed. Measurements were taken from ground level to heights of 15000 ft. The results are plotted in number of ions per cc. (separate curves for positive and negative) at different altitudes.The results indicate that at the cloud level there is an abnormal excess of small positive ions and a minimum in the excess of positive ions over negative ions from 4000–6000 ft. higher. This does not include large ions such as charged water drops or dust particles. The observations were taken in regions free from clouds, the cloud level being determined by observation on clouds in the sky, and by relative humidity measurements taken at the same time.