Abnormal rise in day temperature due to absence of dry cold wind from north

Bhubaneswar: Feeling of summer heat in Ocober has caused consternation among weather watchers with the temperature abnormally soaring to 36 degrees C in the capital city on Wednesday which is four degrees C above normal.

The night temperature on Wednesday was found to be 27.4 degrees C which was 3.5 degrees C above normal, Dr. Sarat Chandra Sahu, Director of SOA’s Centre for Environment and Climate (CEC) here said.

Dr. Sahu said temperature recorded at CEC in October between 2019 and 2023 and at SOA’s agriculture farm at Chhatabar on the outskirts of the city indicated the sharp rise in temperature. As Chhatabar is located away from the city in a rural setting, the day and night temperature at the farm indicated a difference of 1.5 degree C against the higher temperature recorded in the city.

One of the causes of the abnormal rise in day temperature was the absence of dry cold wind from the north and north-east due to movement of low pressure over Odisha on September 29 and 30 towards North Jharkhand, West Bengal and Bihar and the consequent cloudburst over Sikkim in the first week of October, he said.

Strong southerly wind flow from the Bay of Bengal towards North of West Bengal and Sikkim was prominent between October 1 and 5, Dr. Sahu said.

Light to moderate rainfall was experienced across Odisha due to a cyclonic circulation and low pressure over the state up to October 4 but moisture with 60 to 65 per cent humidity and cloud cover caused the day temperature to hover between 30 to 33 degrees C up to October 5, he said.

As rain stopped from October 4, presence of 60 to 65 per cent humidity in the lower atmosphere and significantly less humidity in the upper atmosphere coupled with westerly wind flow towards Odisha favoured the rise of day and night temperature from October 6, Dr. Sahu said adding day temperature remained 35 degrees C (or more) and night temperature was 27 degrees C (or more) from October 6.

This trend is expected to continue till October 18, he said.

He explained that the high humidity in lower atmosphere did not favour rain in the absence of any circulation to push the moisture upwards for cloud formation and subsequent rain. So the moisture remained in the lower atmosphere while the clear sky allowed penetration of solar radiation towards earth’s surface.

Models, however, indicate that wind patterns could change from October 18 due to formation of a cyclonic circulation over the south Bay of Bengal which is expected to favour decrease of day and night temperature, he said.