THE WINTER months of December-January will have the met department roll out the ‘chill index’, just the same way as it had announced ‘heat index’ for the summers.
With 100 major cities, including Pune to have incorporated this, the met department will give area-specific temperature guide to people.
Met officials said that just as the heat index, the department has decided to introduce the chill index as they got repeated feedback from people that they felt either colder or less cold than the temperature predicted by the meteorological department.
The timely updates are bound to help people. Just as the heat index is defined for summer, the wind chill index is defined for winter and is determined by temperature under various wind speeds and temperatures, said Met department officials.
“We had started the trials early this year and we should be operational this December-January for 100 major cities, including Pune. Following the success of this experiment, it would be replicated in all the cities by next year,” said Additional Director General of Meteorology B Mukhopadhyay of the project.
Explaining further, he said, this programme is part of the Climate Services Programme and the chill is usually calculated on the basis of factors such as expected air temperature, relative humidity and wind strength at 5 feet–the typical height of a person’s face. This is calibrated with an understanding of how heat is lost from the human body on cold and windy days.
According to met officials, we feel colder because our skin temperature is lower and the sensation of cold is what the wind chill index quantifies.
The officials add that as such an index is not real temperature and is expressed without units, even though it is calibrated according to the Celsius temperature. In general, the feeling of minimum temperature is much below the actual due to winds called wind chill and this will be put up by the National Weather Forecast Centre for the cities. Also, to boost the people-to-people connect, an interactive website will seek opinion of people on weather updates in their areas.
According to weather forecasters, people often feel colder than the actual temperature. This is due to the wind chill factor. The IMD, as part of its Climate Services Programme under the Health and Climate Programme, plans to create an interactive website through which people can give their feedback in the section “feels like”. Based on these responses, the IMD will get additional help in calculating the ‘chill index’.
For example, if the minimum temperature given by Met officials is 10°C, the website will ask people to quantify how cold they feel. Citizens can make their entries, anywhere between 9°C and 12°C, said Mukhopadhyay.
The objective behind issuing a specific city-wise heat advisory is to help local governments and civic bodies to take precautionary measures in advance to protect from heat wave. This year being the hottest, the proposal was mooted but did not take off as expected. The advisory was to be given through colour-coded maps, marking comfortable, uncomfortable and highly comfortable levels, which was to be updated every three hours. This forecast was mainly based on temperature and relative humidity and if the temperatures were high, the colour scheme was to reflect ‘uncomfortable’ and if the temperatures increased, it was to be shown as highly uncomfortable.