Module 09: Radar basics for spotters

A network of about 160 radars run by three agencies, each one listening far more than it talks, and each measuring two things that are not what you think they are. (25 min)

Why the radar sees higher and coarser the further out it looks, what sits directly overhead that it cannot see at all, and how to spot an echo that is not weather. (30 min)

What a volume scan is, what the low-level supplementary cuts buy you, and the arithmetic that converts data age into distance on the ground. (25 min)

A logarithmic scale, a conversion that is an assumption rather than a measurement, and the difference between the two reflectivity products your app offers. (25 min)

Hook echo, inflow notch, weak echo region, three-body scatter spike, bow echo and debris ball. Six shapes, and six limits on what they mean. (30 min)

Radar measures motion along the beam and nothing else. Everything confusing about the velocity display follows from that one sentence. (30 min)

Three new fields, one of which answers a question the old radar could not: is what I am looking at even made of water? (30 min)

One grid built from the whole network, updating every couple of minutes, and four derived products that are estimates rather than observations. (25 min)

Radar is for knowing where to be and what is coming. It is not a source of observations, and a report sourced from it is not a spotter report. (25 min)

Six well-documented events from six parts of the country, each illustrating one limitation this module has spent nine lessons describing. (30 min)