Officials of the Meteorological Department said a combination of factors led to such dense fog that blanketed most parts of the city.
Chennaiites woke up to dense fog that descended over the city on Friday morning with visibility falling below 50 metre in several places, particularly around Meenambakkam, according to the Meteorological Department.
The visibility improved in many areas only after 8.30 a.m. Officials of the Meteorological Department said a combination of factors led to such dense fog that blanketed most parts of the city.
B.Amudha, Scientist-E and in-charge, Aviation Meteorological Office, Meenambakkam, said the visibility dropped below 50 metre between 5.30 a.m. and 8.30 a.m. over the Chennai Airport. It improved to 2,000 metre around 9 a.m.
Clear skies and calm winds that prevailed on Thursday night led to formation of dense fog. “The outgoing radiation emitted by earth escapes faster because of clear skies. The earth’s surface also cools off and the moisture content in lower atmospheric levels due to high relative humidity became favourable for formation of dense fog,” said Ms. Amudha.
Long wave radiation would not get trapped if there were winds. The relative humidity was close to 100% around 5.30 a.m. over Meenambakkam and it was 97% around 9 a.m. on Friday. This also led to an increase in minimum temperature to 24 degree Celsius in both the weather stations at Nungambakkam and Meenambakkam.
The Meteorological Department predicts light rains in one or two places of interior Tamil Nadu on Friday and dry weather would continue over the rest of the State. During the past 24 hours ending 8.30 a.m. on Friday, Sankarapuram and Kadavanur in Kallakurichi district received light rains of 2 cm.
Chennai will experience partly cloudy sky and mist will occur in some areas during early morning hours till the weekend.