Section 01
Arithmetic
A forecast you calculate rather than guess.
This section
Pieces5
Long reads3
Opens withSix Weeks of Arithmetic for Six Hours of Weather
Six Weeks of Arithmetic for Six Hours of Weather
Richardson calculated a single six-hour forecast by hand in 1922.
Bjerknes states the problem
Before anyone could calculate a forecast somebody had to say precisely what calculating one would mean: a set of equations, a set of initial measurements, and no meteorology in between.
Why it came out wrong
The arithmetic was sound; the initial data was not smoothed, so the calculation amplified noise that was never in the atmosphere.
Sixty-four thousand people with slide rules
His estimate of what it would take to keep pace with the weather, arranged in a hall like an orchestra, is the clearest picture of what a model does.
What a Forecast Actually Is
A probability dressed as certainty, derived from a snapshot that no one quite gets right.
Every piece in Arithmetic
The same set as a list, for reading rather than browsing.
- Six Weeks of Arithmetic for Six Hours of WeatherLongRichardson calculated a single six-hour forecast by hand in 1922.
- Bjerknes states the problemLongBefore anyone could calculate a forecast somebody had to say precisely what calculating one would mean: a set of equations, a set of initial measurements, and no meteorology in between.
- Why it came out wrongLongThe arithmetic was sound; the initial data was not smoothed, so the calculation amplified noise that was never in the atmosphere.
- Sixty-four thousand people with slide rulesMediumHis estimate of what it would take to keep pace with the weather, arranged in a hall like an orchestra, is the clearest picture of what a model does.
- What a Forecast Actually IsShortA probability dressed as certainty, derived from a snapshot that no one quite gets right.
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