Weather forecasting and early warning

What a Doppler Weather Radar does

• A Doppler Weather Radar sends out a microwave pulse and reads the echo returned by raindrops, snow and hail, which tells it where precipitation is and how heavy it is.
• The Doppler effect in that echo also gives the speed at which those drops are moving, so the radar reads the wind inside a cloud and not only the rain falling out of it.
• Because it scans again every few minutes it follows a storm or a cloudburst as it develops, which is what turns a forecast into a warning.

Why the hills are harder

• A radar beam travels in a straight line, so a ridge standing in front of it blocks the beam and the valley behind that ridge goes unwatched, which is beam blockage.
• Siting is a trade-off: a radar placed high sees over more ridges, but its beam then passes above the low cloud that is dropping the rain.
• A cloudburst builds and empties within the hour, so a gap in cover is not a slow loss of accuracy but a warning that never comes.

The network behind a warning

What Mission Mausam is

• Mission Mausam is the Ministry of Earth Sciences programme to widen India's observing network, sharpen its models and take up weather modification research.
• Phase one ran from 2024 to 2026 and built most of the network above.
• Its targets are set for 2030: forecasts 10 to 15 per cent more accurate, and hazard forecasts on a 5 km by 5 km grid reaching every household.