Kalpathi Ramakrishna Ramanathan obtained DSc (1923) from University of Madras. He remained Honorary Director, Trivandrum Observatory (1918-21); Meteorologist, India Meteorological Department (1926); Director, Kodaikanal and Bombay Observatories; Superintending Meteorologist, Deputy Director-General and Officer on Special Duty (1938-48); also Director (1948-66) and Emeritus Professor (1966-84), Physical Research Laboratory, Ahmedabad.

Academic and Research Achievements: Dr Ramanathan’s main fields of research related to: molecular scattering of light and X-rays diffraction in liquids, gases, mixtures and anisotropy of molecules. At Indian Meteorological Department, he studied Solar and atmospheric radiation, the spectrum of the night sky, meteorological optics and acoustics, atmospheric ozone, terrestrial magnetism, seismology, studies of the general circulation of the atmosphere in its global and regional aspects, the Indian monsoon circulation, monsoon depressions and cyclonic storms of the India Seas. His contributions in the thermal structure and movements of upper air, as well as in the field of atmospheric ozone are outstanding. He was the first to publish the now famous diagram showing the distribution of upper air temperatures over the world upto 25 km in summer and winter. As Director of Physical Research Laboratory, his major contributions to the study of atmospheric ozone were: (i) the discovery of the quasi biennial oscillations of total ozone in the tropics, (ii) the dependence of ozone distribution on meteorological phenomena such as jet streams and their location, tropopause discontinuities and inter-latitudinal air exchange, and (iii) on the whole its relationship with the general circulation of the atmosphere. These studies led to a large number of theoretical investigations by several authors on the behaviour and transport of ozone in the upper atmosphere. In International circles, Professor Ramanathan used to be called Mr Ozone. Besides ozone, he was mainly connected with studies of night air glow, ionospheric and space physics and solar and galactic influences on the ionosphere. He established the nocturnal and seasonal variations of the green and red lines of oxygen, and the effect of solar flares on the green emissions. Another significant contribution, was the estimation of the role of secondary and higher order scattering in twilight. The contributions to ionospheric physics by Professor Ramanathan and his students at PRL, Ahmedabad over a period of nearly thirty years, have been outstanding. They are the effect of electron-ion collision in the F-region of the ionosphere on the absorption of cosmic radio noise, the effect X-rays from discrete galactic sources to the lower ionosphere, and the existence of atmospheric general circulation systems in the ionospheric regions also.

Other Contributions: Under Ramanathan’s stewardship, the Physical Research Laboratory, Ahmedabad, grew into one of India’s leading research centers. His involvement with International Geophysical Year (IGY) was a great fillip to PRL’s growth. He was also INSA Council Member (1942-44).

Awards and Honours: Dr Ramanathan was recipient of the International Meteorological Organization Award for Meteorology (1961); Padma Bhushan (1965); SK Mitra Memorial Lectureship by INSA (1966); Padma Vibhushan (1976); and Aryabhatta Medal by INSA (1977). He was Foundation Fellow, Indian Academy of Sciences, Bangalore; Honorary Fellow, Royal Meteorological Society, London; President, Mathematics and Physics Section, Indian Science Congress (1939), International Association of Meteorology (1951-54), International Ozone Commission (1960-67); and Vice President, INSA (1955-56).

The Indian National Science Academy has instituted ‘Kalpathi Ramakrishna Ramanathan Medal’ in his honour.