Kerala frost
© Kerala Tourism/Twitter
As the snow blanketed north India's Uttrakhand, Kashmir and Himachal Pradesh on Monday, Delhi woke up to a chilly morning with the fog impacting visibility, hitting transport services. While such developments are relatively mundane when it comes to Delhi and northern part of India at this time of the year, what is happening in an otherwise tropical Kerala has left many baffled.

The usually pleasant Kerala hill station of Munnar has been experiencing sub-zero temperatures since the New Year arrived. As per reports, Munnar experienced a dip as low as -3 degrees Celsius the previous Wednesday, which severely affected acres of tea plantations in the region.

Kerala Tourism tweeted frost covered pictures of Munnar with a tweet, "We woke up to a chilly surprise this morning. Take a guess where; it's perhaps our most popular hill station."

Located at an altitude which ranges from 1,450 meters (4,760 ft) to 2,695 meters (8,842 ft), Munnar is no stranger to low temperatures, however, the chill in the region this year is something it has not experienced in the last 10 years. The hill station has not experienced any snowfall so far but the mercury was low enough to turn the morning dew into frost every morning, giving the region a generous spread of the white layer.

And it's not just Munnar, most towns of Kerala are experiencing relatively lower temperatures ranging from 17 to 20 degrees Celsius since the past few weeks.

Additionally, what is intriguing is the fact that the gap in the daytime and night time temperatures in Kerala are said to be imitating desert-like conditions which is admittedly abnormal in the southern state.

Manoj M, a scientist at Cochin University of Science and Technology (CUSAT), attributed it the sudden weather change to "the weakening of the polar vortex", saying that this causes "a sudden atmospheric warming over the north pole at the level of the stratosphere", reported Manoramaonline.

And when the stratosphere over the north pole is warmed, that over the tropical regions is cooled, and hence the weather in Kerala, he concluded.

The dip in the mercury is quite rare in a rather pleasant southern state of Kerala, especially in the recent decades.