Orange alert in Delhi-NCR: What is driving the intense rain, hailstorm?
Delhi-NCR received sudden rain and hail on April 30, offering relief from an intense heatwave that pushed temperatures close to 44 degrees Celsius. Here is the science behind it.
Delhi woke up to a sky that couldn’t make up its mind. Blazing Sun one moment, dark clouds and hailstones the next.
On April 30, rain and hail swept across the Delhi-NCR region, catching residents completely off guard and offering instant relief from a punishing stretch of heatwave conditions that had pushed temperatures close to 44 degrees Celsius in several pockets of the capital.
But what exactly triggered this dramatic and sudden shift in weather?
WHY IS THERE RAIN AND HAIL TODAY?
The answer lies in a classic clash of winds. Delhi is currently caught between two opposing air masses: dry, hot westerly winds blowing in from Rajasthan, and moist easterly winds carrying humidity all the way from the Bay of Bengal.
When these two very different air masses collide, the atmosphere turns deeply unstable.
Think of it like hot oil meeting cold water. The result is turbulent and explosive.
This instability triggers what meteorologists call convective activity, which simply means warm, moist air near the surface rises rapidly into the cooler atmosphere above.
As it rises, it cools down, condenses, and forms towering storm clouds known as cumulonimbus. These are the classic thunderstorm clouds that can darken an entire sky within minutes.
WHAT CAUSES HAIL TO FORM INSIDE THESE CLOUDS?
Inside these storm clouds, powerful upward gusts of wind, called updrafts, carry water droplets high into the atmosphere where temperatures are well below freezing. The droplets freeze into ice pellets.
These pellets then get coated in more water as they are tossed up and down repeatedly inside the cloud, growing larger with each cycle, until they become too heavy to stay aloft and fall to the ground as hailstones.
HOW BAD COULD IT GET?
These weather systems are expanding across the region. Short bursts of heavy rainfall, thundershowers and possible hailstorms could affect 20 to 30 per cent of Delhi-NCR, 30 to 40 per cent of Haryana, and up to 50 per cent of districts in western Uttar Pradesh.
Coverage remains patchy, and not every locality will experience the same intensity.
Intense activity is expected to continue until around 7 PM. Residents are urged to avoid open areas during lightning and watch out for waterlogging in low-lying spots.
For now, at least, Delhi is finally catching its breath.