The Weatherman Is Not a Moron: This is a really interesting article about how computers are making weather forecasting better.
In 1972, the service’s high-temperature forecast missed by an average of six degrees when made three days in advance. Now it’s down to three degrees. More stunning, in 1940, the chance of an American being killed by lightning was about 1 in 400,000. Today it’s 1 in 11 million
One of the problems is that all the atoms swirling around in the atmosphere is just a lot of data to keep track off, and small errors have massive implications.
After spending weeks double-checking their hardware and trying to debug their code, Lorenz and his team discovered that their data weren’t exactly the same. The numbers had been rounded off in the third decimal place. Instead of having the barometric pressure in one corner of their grid read 29.5168, for example, it might instead read 29.517.
When you think about it, analyzing weather might be the largest physical problem in the world. It’s certainly the problem with the largest physical component – the entire atmosphere. The scale of the problem in numbers is defined by how granular you divide up the physical domain.