A towering wall of dust is sweeping across Delhi and the National Capital Region (NCR), with thunder, lightning and rain.
The India Meteorological Department had warned of a dust storm trailed by thunderstorms, with winds of 50 to 70 kilometres per hour.
Aandhi is the local name for the violent pre-monsoon dust storms that hit northwest India in late May.
Fierce summer heat warms the ground and makes the air unstable, the fuel storms feed on.
Dry, loose soil from Rajasthan and the Thar Desert supplies the dust.
Inside a growing storm cloud, cool air plunges towards the ground in a downdraft.
When it lands, it spreads outwards as a gust front, a sudden rush of wind that scoops soil into a moving wall, also called a haboob.
The same tall cloud then releases its rain.
WHY IS THERE SO MUCH LIGHTNING?
High up, ice crystals and water droplets smash together and swap electric charge.Lighter positive charges gather at the top and heavier negative ones sink to the base.When the gap grows large enough, it snaps as a lightning bolt, and the air it heats expands to give the thunderclap.
HOW DO SATELLITES SPOT THESE STORMS COMING?
Forecasters watch water vapour satellite images, which sense moisture in the middle and upper atmosphere.Dark patches show dry air higher up, while bright white areas reveal damp air or tall storm clouds.
These pictures also trace the high winds and jet streams that steer and organise the storms.
The IMD says the heat wave has eased over central India, and Delhi's maximum is several degrees below normal, around 36 to 38 degrees Celsius.
The rain also marks the advancing southwest monsoon, though a below normal season is expected, near 90 per cent of the long period average, as El Nino builds.
Source: India Today