The ion-aerosol balance equations have been solved for different mixing str
engths and two types of ionization profile to get vertical profiles of atmo
spheric electric parameters close to the Earth's surface. The inclusion of
surface radioactivity in the model causes the decrease in electric field to
be more intense at lower levels than at higher levels, an increase in the
asymptotic value of the field, and an increase in the space charge density
gradient. When the mixing of atmosphere is very weak, a reverse electrode e
ffect is observed under the condition of enhanced ionization due to trapped
radon, with the decrease in ion densities above 1 m. However, with an incr
ease in eddy diffusivity, the positive ion concentration decreases, and the
negative ion concentration increases with increasing height above the diff
usion layer. Further increase in eddy diffusivity causes the profiles to be
come almost similar to those for which the ionization is constant with heig
ht. Even with the inclusion of radon radioactivity, relatively higher diffu
sivity keeps the nature of the profile of the negative ions similar to that
for the constant ionization case. On the contrary, there is a drastic chan
ge in the profile of positive ions because of the strong downward gradient
of positive ions in the diffusion sublayer. The profile of positive ions is
more sensitive to the radon radioactivity and that of negative ions to the
strength of turbulence. Further, the asymptotic value of aerosol concentra
tion is reached before that of small ions when mixing is very low. Our resu
lts are in reasonable agreement with the earlier theoretical and experiment
al studies.