David Hirst, age 12, of Allentown, Pennsylvania, for his question:

What causes the doldrums?

There are two types of doldrums, one personal and one global. A personal attack of the doldrums is a gloomy spell of depression. It may be caused by boredom, indigestion or almost any other ailment. The global doldrums is a depressing region, caused by a loop in the pattern of prevailing winds. It was named by the mariners of old sailing ships because to them, a doldrums was a dull depressing person or a dull depressing mood.

The dreary situation occurs because the north and south trade winds arrow towards the equator. There, all around the wide waist of the world, warm light air ascends in rising currents. This creates a region of calm which is most noticeable on the ocean. Day after day, sometimes week after week, there is never a breeze to ruffle the waves. This region of equatorial doldrums is depressingly calm because currents of air are moving vertically.