You be the Forecaster

摘要

When winter arrives, snow-storms grab the headlines. However, cold waves are just as important. Not only do they shape the day-to-day lives of millions of people, but they have a great effect on agriculture, construction, and the petroleum industry. This issue's puzzle takes us to the core of the cold snap: the polar air mass. One hint: no fronts will be found! Draw isobars every four millibars (992, 996, 1000, 1004, etc.) using the plot model example at the lower right as a guide. As the plot model indicates, the actual millibar value for plotted pressure (xxx) is 10xx.x mb when the number shown is below 500, and 9xx.x when it is more than 500. For instance, 027 represents 1002.7 mb and 892 represents 989.2 mb. Therefore, when one station reports 074 and a nearby one shows 086, the 1008 mb isobar will be found halfway between the stations.