Week 02 — When Does Bad Weather Become a Drought?
Building an operative definition: threshold, span, recovery allowance, scope, season.
Week 02 · definition · 3 August 2026
You cannot design against an event until you define it, and changing the definition changes what counts as failure.
- Property
- definition
- Stance
- Complicates it
- How
- The same fortnight, classified four ways.
- Studio activity
- Vary threshold, duration, area and source mix, and watch which periods survive classification.
Week 1 asked you to find the worst period. This week asks what gave you the right to call it an event at all.
How this complicates the thesis#
The thesis says a defensible design names the event it survives. Week 2 shows that naming is not a neutral act. Four defensible-looking definitions applied to the same fortnight produce four different sets of qualifying periods — sometimes including the empty set. The line is a modelling decision, and it decides what the rest of the semester is even allowed to see.
In the session#
We classify one fortnight several ways, changing the threshold, the minimum span, the recovery allowance and which sources count. You watch periods appear and disappear from the qualifying set without the weather changing at all.
The dial below is the instrument we use. It runs the course’s own classifier over the shared trace, so what you see is what the definition actually selects.
Its relationship to the canonical event#
This is the week that earns the event. That page fixes one definition so the cohort argues about systems instead of vocabulary — and it says plainly that the boundary is contestable. Here is where you contest it.
What next week needs#
Once you can define an event, the next question is whether generators fail independently of one another. Week 3 shows they do not.
The definition dial
Move a control and watch which periods qualify.
Combined wind and solar output across fourteen synthetic days, counting wind and solar together, against a 12% threshold and a 48-hour minimum span. One period qualifies as an event: a 61-hour trough beginning on day 8, with output falling to 0.9% of capacity. six shorter low periods are rejected by the duration rule.
- Events found
- 1
- Longest span
- 61 h
- Worst starts
- day 8
- Lowest output
- 0.9%
- Rejected as too short
- 6
At the course definition, one period qualifies — 61 hours beginning on day 8. Six low periods are rejected for being too short, so the duration rule is doing most of the discarding.
A sandbox for the definition, not a change to it. The course's own boundary stays as published. Output series Synthetic trace, boundaries you set here are yours to defend.
The spec
What to bring. Written so you can tell whether you have met it without asking.
- you can state what you looked for in week 1's trace, in numbers
- you have read the course's operative definition