The effect goes beyond simple self-report and plays out in decisions that matter a great deal. On rainy days, students looking at potential colleges pay more attention to academics than they do on sunny days—and for every standard deviation increase in cloud cover on the day of the college visit, a student is 9 percent more likely to actually enrol

All to the north the rain had dragged black tendrils down from the thunderclouds like tracings of lampblack fallen in a beaker and in the night they could hear the drum of rain miles away on the prairie.

The NWS keeps two different sets of books: one that shows how well the computers are doing by themselves and another that accounts for how much value the humans are contributing. According to the agency’s statistics, humans improve the accuracy of precipitation forecasts by about 25 percent over the computer guidance alone,31 and temperature foreca