iurnal variation of atmospheric electric field for a single station Kew has been analysed for two consecutive years 1974-75. Harmonic analysis shows that the constant term is the primary factor ill determining the value of the parameter at any time while the diurnal variation of the parameter is almost entirely governed by the diurnal and semi-diurnal components of harmonic analysis. Analysis also shows that diurnal component is most significant during winter, whereas the semi-diurnal component is in equinox. During summer the two components become minimum. Attempt is also made to explain the physical significance of the two components with the help of existing theories.