Abstract
Based on the distinct climatic zones in India, exponential and bi-exponential models of radio refractive index have been derived by least squares determination of 4 years mean values of radio refractive index from ground surface to 100 mb level. The calculation of radio refractive index is based on the radio sonde data of 12 stations in India displaying various air mass characteristics.
The results show that exponential model of radio refractive index is fairly good representation over India at 850 and 700 mb levels over the country except over coastal stations of the peninsula at 700 mb where the bi-exponential model showed better agreement.