The residents of North and Central India are in for a challenging week as a severe heatwave is expected to commence on June 8with temperatures potentially reaching a blistering 46 degrees Celsius. This intense heat spell is set to test the resilience of those living in the affected regions, stretching from Punjab to Uttar Pradesh.
Independent weather forecaster Navdeep Dahiya has warned of a significant rise in daytime temperatures across PunjabHaryanaRajasthanDelhi-NCRand Uttar Pradesh. The peak of this heatwave is anticipated around June 10 and 11with some relief expected by Friday.
The Science Behind the Rising Temperatures
The primary driver of this heatwave is a continuous stream of hot, dry winds blowing in from the northwest, a phenomenon scientists refer to as advection. These winds, known as loo windssweep across the Thar Desert and the dry plains of Rajasthan and Pakistanabsorbing heat as they travel. The relentless flow of these winds pushes aside any cool air that forms locally, replacing it with more hot air.
Adding to the intensity of the heat is a ridge of high pressure, or anticyclonethat often parks itself over the region. This high-pressure system acts like an invisible lidpressing warm air downwards. As the air sinks, it gets squeezed and warms up further, a process known as subsidence. The lid also clears away clouds, allowing the strong June Sun to beat down with little obstruction. This outcome is sometimes referred to as a heat domewhere warmth is trapped near the ground.
The Role of Dry Soil and the India Meteorological Department’s Criteria
Dry soil exacerbates the situation. With little moisture left to evaporate, almost all the Sun’s energy goes into heating the air rather than turning water into vapor. This is why parched land bakes the fastest. The India Meteorological Department (IMD) declares a heatwave in the plains when the maximum temperature crosses 40 degrees Celsius and runs at least 4.5 degrees above normalor simply when it touches 45 degreeswhichever comes first.
A forecast of 42 to 46 degrees comfortably meets the IMD’s criteria for a heatwave, especially across west Rajasthan and the Bundelkhand belt of Uttar Pradesh.
When Will the Heatwave Break?
Relief is on the horizon. A western disturbancea band of moisture-carrying winds that travels eastward from the Mediterraneanis expected around June 13. This disturbance will bring clouds, a chance of rain, and a change in wind direction, knocking the temperature down by a few degrees. However, the monsoon, which reached Kerala on June 4is still far from the north. Until it climbs up the map, these short, fierce heat spells will keep returning.
In the meantime, residents are advised to keep their curtains drawn, stay hydrated, and keep the loo winds at arm’s length.
