When giving thanks this year, think of Lena Woebbecke. She and many others paid a terrible price for misreading the prairie sky on the afternoon... 1888. That day was unseasonably balmy, by prairie standards — some temperatures were in the 20s — and many children scampered to school without coats or gloves. Then, at about the time schools were adjourning, death, in the shape of a soot-gray cloud, appeared on the horizon of Dakota Territory and Nebraska. In three minutes the temperature plunged 18 degrees. The next morning hundreds of people, more than 100 of them children, were dead beneath...