http://hdl.handle.net/2248/1705 2026-05-14T16:56:29Z 2026-05-14T16:56:29Z Das, A. K http://hdl.handle.net/2248/6631 2020-10-27T14:08:09Z 1938-01-01T00:00:00Z

Progress of meteorology in India Das, A. K Open Access

1938-01-01T00:00:00Z Das, A. K Ramanathan, A. S http://hdl.handle.net/2248/4530 2020-12-07T10:13:45Z 1953-01-01T00:00:00Z

Distribution of radiation flux across a sunspot Das, A. K; Ramanathan, A. S Open Access

1953-01-01T00:00:00Z Das, A. K Abhyankar, K. D http://hdl.handle.net/2248/4529 2020-10-27T13:45:35Z 1955-01-01T00:00:00Z

Temperature at the poles and at the equator of the sun Das, A. K; Abhyankar, K. D The equivalent widths of the g and K lines are measured at the pole and at the equator of the Sun during a period of minimum solar activity. The difference of temperature between pole and equator is evaluated by Woolley's method of the calcium ionization temperature. The pole is found to be hotter than the equator by 96° ± 18° or 86° ± 16°, depending upon the choice of the values of the continuous absorption coefficients. This result lends support to Bjerknes's thermohydrodynamical theory of sunspots. Using Bjerknes's theory, the depth of the sunspot umbral column is calculated from the observed difference of temperature between pole and equator and is found to be 125 km or 140 km. Restricted Access

1955-01-01T00:00:00Z Das, A. K http://hdl.handle.net/2248/4518 2020-10-27T13:13:34Z 1952-07-12T00:00:00Z

Kodaikanal Observatory Das, A. K Restricted Access

1952-07-12T00:00:00Z