Quick Facts
Biography
L. A. Ramdas (1900–1979) was an Indian physicist and meteorologist, known for discovering the atmospheric phenomenon of the Ramdas layer or Lifted Temperature Minimum where the lowest temperature in the atmosphere is not on the ground but a few tens of centimeters above the ground.
Life
Ramdas was trained in physics and was a student of C. V. Raman, and worked for many years in the Indian Meteorological Department. By 1931, he was working on agricultural meteorology at the Met observatory at Pune.
During this period, he started a project on "Weather in relation to crops" which was to become the "Agri Met" division of the IMD, among the earliest groups in the world to have such a specialization. As part of this work, he started lookiong at climate phenomena near the ground.
Ramdas was a Fellow (since 1935) of the National Institute of Sciences of India (which became Indian National Science Academy in 1970). He also served as President of the Physics Section of the Indian Science Congress. He was also a recipient of the Padma Shri Award. He received the title of the Member of the Order of the British Empire (MBE) in 1945.
L.A. Ramdas died on January 1, 1979.
Discovery of Lifted Minimum Temperature
At the time, it was believed that the temperature at night is lowest at the ground and increases with altitude. These were based on meteorological observations that started taking temperature measurements of the atmosphere starting at a height (called the screen height) of 1.2m from the ground.
Ramdas however, conducted such measurements at a number of points closer to the ground. Observations conducted at Pune, Agra, Madras and Bhadrachalam all indicated that on clear windless nights, the minimum temperature is not on the ground but is lifted by a distance between 20 and 50 cm.
The phenomenon was first reported in a 1932 paper by Ramdas and S. Atmanathan in the journal Beiträge zur Geophysik. Initially, these observations were doubted but they have been replicated widely in subsequent decades by others. The phenomenon has been named the Ramdas Layer, and is attributed to the interaction of thermal radiation effects on atmospheric aerosols and convection transfer close to the ground.