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Module 03

Cloud & storm-structure identification

Naming what you are looking at, and telling it apart from the thing it resembles. Eleven lessons that work down the storm from the anvil to the ground, ending at the two hardest calls a spotter makes: is that lowering outflow or inflow, and is that a tornado or not.

Start lesson 01

Lessons11

Reading timeabout 4.5 hrs

Objectives45

The lessons

Take them in order, or don't

01Cloud building blocks for spottersBefore you can tell two features apart you have to be able to name them. This is the vocabulary the other ten lessons are written in.Visual IDCloud taxonomy to exactly the depth a spotter needs, and no further. Enough to name the stage, not enough to sit a WMO exam.20 min 02Upper storm structureOvershooting top, backsheared anvil, striations, flanking line, mammatus. Four of those tell you about the updraft. One of them tells you nothing, and is the most misreported cloud in the sky.Visual IDThe top of the storm is the part you can see from furthest away, and it is the part most spotters never learn to read.25 min 03The updraft base and the precipitationTwo regions under a storm, doing opposite things. Getting the boundary between them right is what makes every later lesson possible.Visual IDIncludes the terminology change the NWS itself made: "updraft base", not "rain-free base".25 min 04Inflow features: bands, beaver tail, tail cloudAir being pulled into a storm makes clouds of its own, and two of them are long, low and sinister-looking from the wrong angle.Visual IDThe inflow-side features that get reported as funnels. NWS Northern Indiana documents this exact false report, repeatedly.20 min 05Outflow features: gust front, shelf, roll cloud, scudThe cold air a storm makes has to go somewhere, and on its way out it builds the most dramatic and most misreported clouds in severe weather.Visual IDThe arcus family taught as a family, so the shelf cloud arrives in lesson 6 already understood as outflow rather than as a mystery.25 min 06Shelf cloud versus wall cloudTwo lowerings. One is the storm breathing out and one is the storm breathing in. Everything about how you report them is different, and this is the call spotters get wrong more than any other.Visual IDThe keystone. This one distinction is the documented dominant spotter error, and it carries a quarter to a third of the module exam on its own.30 min 07Funnel, tornado, and the reporting thresholdThere is a bright line between a funnel cloud and a tornado, it is written down, and it is not about how the thing looks.Visual IDThe exact test, in the exact words module 7 will use, so the two modules cannot drift apart.25 min 08Gustnado, landspout, dust devil, waterspoutNot every spinning thing under a storm is a tornado, not every tornado comes from a mesocyclone, and the boundary between those two statements is genuinely disputed.Visual IDIncludes the hard part: the experts do not fully agree on what counts as a tornado here, and you should know that.25 min 09Classic, HP and LP from the groundThe same storm type in three costumes. One of them shows you everything, one shows you enough, and one shows you nothing while doing everything.Visual IDModule 2 gave you the three archetypes as environments. This is what they look like through a windshield, and which one is trying to kill you.30 min 10What a squall line looks like from underneathA line of storms gives you a shelf cloud, a lot of wind, and almost none of the visual vocabulary the rest of this module just taught you.Visual IDTreats QLCS spotting as its own skill rather than as supercell spotting with the storm in a different shape, because visually it is a different job.25 min 11Perspective, light, distance and darknessEverything you have learned to identify can be made unrecognizable by the angle you are standing at, the light behind it, or the ten miles between you and it.Visual IDThe lesson about the observer rather than the storm. It comes last so it can use every feature in the module as a worked example.20 min

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