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This is an archive article published on February 12, 2024
Know Your City: From thermometers under a thatched roof to GPS data, the evolution of weather forecasting in Bengaluru
In 1894, the Mysore State Met Meteorological Department came into being, and was later merged with the IMD. The older instruments at IMD, Bengaluru will be on display on Feb 28, National Science Day.
3 min read
Bengaluru residents have relied on IMD's weather forecasts for years, with the headquarters using cutting-edge instruments.(Representational Photo)Whether it is the scorching heat of an unseasonal February or the likelihood of flooding after heavy rain, Bengaluru residents have long relied on the weather forecasts of the India Meteorological Department (IMD). Today, the weather office’s headquarters near Palace Road uses cutting-edge instruments but long ago, things were not so smooth.
According to A Prasad, scientist at IMD, the first instruments were set up in a makeshift observatory on the premises of Bowring Hospital the year before the hospital was formally opened in 1868. The only instruments at the time were a few thermometers, housed under a thatched roof. While the initial work had been done at the suggestion of the Asiatic Society of Bengal, one Professor John Cook of Central College, Bangalore took the initiative to have the observatory moved there in 1892. Cook is today remembered as the first Director General of the observatory, Prasad says.
Mysore State Meteorological Department
The very next year, an observatory was built at the current IMD premises along the lines of the observatory in Kolkata’s Alipore, built in 1877, after Cook raised the matter with the Mysore government. Unfortunately, this building no longer exists, having been demolished after time took its toll on the structure. In 1894, the Mysore State Meteorological Department came into existence, and was later merged with the IMD after Independence.
Prasad says, “In the initial thatched structure, only temperature was taken with the thermometers. Slowly, in the later years, we were able to take upper-air observations as well. The surface parameters are not enough – we need to know what is prevailing in the upper atmosphere with wind speed, wind direction, dew point, humidity, etc. Later, pilot balloon observation and radio sounding were started.”
Today, GPS data has been added. Satellite and other data all come together at the Automatic Weather Station on the main premises, a large antenna-like structure several metres high that measures several parameters at once.
Older instruments
However, the older methods have not been neglected. A ‘Stevenson screen’ box nearby houses several antique thermometers, measuring the temperature in much the same way as it might have been done in 1867. Other throwbacks include a hair hygrometer – which relies on the properties of specially treated human hair’s reaction to the humidity in the air to inscribe a graph, a beaker measuring rainfall, and a pond exposed to the elements used to measure the rate of evaporation.
The main observatory houses several older instruments as well, despite modern equipment providing precise data, including a weathervane linked to an ink-based graph a floor below, and a spherical lens measuring the intensity of sunlight by burning the material placed beneath it.
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The older instruments at the IMD will be on display to the public on the occasion of National Science Day which is observed on February 28, when IMD officers will explain their functioning in detail to visitors.
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