The pulse rates of atmospherics at 10 and 28 kHz have been compared with the variations of outside air temperature up to a height of 7 km. In the 10 kHz band the pulse rate showed a strong statistically significant correlation with air temperature for all heights up to 7 km, the maximum correlation coefficient beingr=0.78 at a level of significanceP≪0.001. In the 28 kHz band the correlation is weaker: up to a height of 3 km the correlation coefficient ranges from 0.17 to 0.3 (P 0.001 and 0.02, respectively) and above 3 kmr ranges from 0.15 to 0.17 (P 0.02 and 0.05, respectively).
As the outdoor absolute humidity depends mainly on the air temperature, it is now clear why previous investigations showed strong correlations between the difference (ΔS) of the atmospherics pulse rates at 10 and 28 kHz, the absolute humidity (AH) outdoors and the diffusion time (TD) of ions in gelatin films, measured in a fully air-conditioned working-room.
Pulse rate of atmospherics Temperature variation Correlation coefficient