Height Variations in the Concentration of Ions Near the Ground During Quiet Summer Nights at Uppsala

Results of measurements of the concentration of small- and large-ions at different heights near the ground during quiet summer nights at Uppsala are given. Characteristic shapes for the variation of the concentration of ions are illustrated. At the ground the concentration of small ions increases more than at higher levels, where also an enhanced content of small ions can be observed during the stated weather conditions. The number of large ions descreases after sunset reaching a minimum at sunrise, after sunrise a comparatively rapid increase follows. It seems that the concentration of large ions near the ground is actually a little below that at the higher levels. Preliminary explanations of the variations are outlined.