Monsoon to hit Delhi and other parts of northern India on June 29
Pre-monsoon showers that hit Delhi and areas in Rohtak and Hisar in Haryana. Pilani and Jaipur in Rajasthan and Sundernagar in Himachal Pradesh on June 18 brought the much needed relief to people in these areas reeling under intense heat waves.
There is more good news. The India Meteorological Department (IMD) has said that these pre-monsoon showers from western disturbances will bring relief from the heat wave to north India over the next few days, too.
Till now, parts of eastern Uttar Pradesh (UP), Punjab, Himachal Pradesh, Uttarakhand, northern Rajasthan, Haryana and pockets of Jammu had been battling an intense heat wave.
IMD defines heat wave as a spell of weather wherein maximum temperature of a station reaches at least 40°C in the plains and at least 30°C in hilly regions. This summer, Lucknow in eastern UP recorded a maximum temperature of 44°C on June 17, which was 5°C above the average maximum temperature, while Amritsar recorded a maximum of of 46.5°C, the highest temperature recorded across the region. In Dehradun, the capital city of Uttarakhand, the temperature on June 17 was 42°C, 8°C more than its average and the record-high in the decade. Heat wave is still predominant in northern India while other parts of the country, including Maharashtra, Karnataka and Tamil Nadu, have been swept by the southwest monsoon.
Heat waves more frequent and intense now
Research shows that these heat waves have intensified in India and have become more frequent. According to an IMD study published in 2004, the number, duration and area of spread of heat waves in India increased sharply during 1991-2000 in comparison to the earlier two decades. The data, which compiled observation from 35 sub-divisions, showed that between 1991 and 2000 average of 22.7 sub-divisions in the country were hit by heat waves each year, while between 1971 and 1980 an average of 9.9 sub-divisions were hit by heat waves per year. During 1981-1990 the average was 7.3. During 1991-2000, the highest duration of heat waves was 16 days, while in the previous decade the longest heat wave was of nine days and a decade before that was 11 days.
D S Pai, senior scientist at IMD’s Pune division, blames the heat wave spell on a combination of factors, including intense sun rays and hot winds from north-western parts of the country. “Intense sun rays are the main cause behind rising temperatures but its impact can be accentuated by hot winds blowing into north India from the north-western desert region.”
IMD continues to rule out climate change from the equation, but Pai adds that increased urbanisation also intensifies the impact of heat waves. Concrete structures like buildings and roads especially trap heat, and release it later, adding to the heat wave effect.
May hit pulse yields
Soora Naresh Kumar, senior scientist with division of environment at the Indian Agricultural Research Institute, New Delhi, says the rising temperatures could adversely affect summer crops like pulses grown in parts of central and northern India. “These crops are grown as additional crops by farmers, because other crops can’t survive in such temperatures. But very high temperatures can affect the yield of summer pulses.”
Going by its current progress, monsoon is set to arrive in Delhi and other parts of northern India around June 29.