Another cold spell likely

The minimum temperature in Delhi on Sunday was 10.5 degrees Celsius.

The disturbances will be the season’s 11th and 12th — normally, no more than five to six western disturbances affect north India each winter.

Meteorologists said the rise in intensity and frequency of these disturbances is an indirect impact of the weakening of the Polar Vortex.

“It’s the end of February, so we are not expecting a cold wave [when the temperature is less than 4 degrees Celsius] but there will definitely be a fall in temperature. Western disturbances mainly develop over the Caspian Sea and Mediterranean Sea, and travels eastwards across Iran, Afghanistan, Pakistan and north India. The system develops due to a temperature difference between northern and southern latitudes. They are more intense this time because of the higher temperature gradient which is a result of the weakening of the Polar Vortex,” explained M Mohapatra, director general of meteorology, at the India Meteorological Department (IMD).

The Polar Vortex is a pocket of very cold air in the northern hemisphere which lies near the Polar region in winter. Due to disturbances in its jet stream, cold air affects parts of US. This year, for instance, large parts of North America were gripped by an influx of Arctic air. There were dangerous wind chills across a significant portion of the Upper Midwest and northeast USA. The US’S national low temperature record was measured at -56 °F (-48.9°C), a statement by World Meteorological Organisation said earlier this month.

Delhi recorded a minimum temperature of 2.6 degrees on December 29, the lowest for the season.