Weather mystery: Why are Bengaluru's days as cool as nights?

Bengaluru: For the next two days, Bengaluru's days are expected to be almost as cool as its nights due to a minimal difference between the maximum and minimum temperatures, according to the India Meteorological Department (IMD). 

On Tuesday, the maximum temperature in the city dropped to 21.9°C, which is 6.6°C below the normal. In contrast, the minimum temperature stayed slightly above normal (20.2°C vs 20°C). As a result, the difference between the minimum and maximum temperatures — diurnal temperature variation — was only 1.7°C. 

Thanks to the incessant rainfall all through Tuesday, the temperatures remained the same throughout with little fluctuation. There was hardly any sunlight anywhere in the city because of the persistent rainfall that began on Monday night. Additionally, easterly winds have brought cold air to the city, explained N Puviarasan, Scientist F and Head, Meteorological Centre, Bengaluru. 

"If there had been no rain or cloud cover through the day, then the maximum temperature would have naturally risen. Additionally, there is a low-pressure area (trough) in the Bay of Bengal, extending up to the (Coromandel) coast, which is why there are cloudy conditions through the day, bringing the temperature down," he told DH. 

The minimum temperatures are also not falling because of the cloud cover. "If there was no wind and cloud cover, then radiation cooling would occur, allowing the heat to pass into the atmosphere. But the cloud cover blocks this cooling process, thus not allowing the temperature to fall further," Puviarasan added. 

The IMD official clarified that the small difference between the minimum and maximum temperatures was a common phenomenon in hilly and inland areas. "These conditions will exist until October 17," he said. 

The IMD has forecast a minimum temperature of 21°C and a maximum of 25°C until October 17. This means that the diurnal temperature variation will remain below 5°C, causing days and nights to feel equally cool.