Where in the world are the “doldrums”?

The doldrums is a nautical term for the Inter-Tropical Convergence Zone, (ITCZ) which extends about five degrees north and south of the equator.

Sailing ships sometimes get stuck in this zone due to light, unpredictable winds in the region, where the prevailing southwesterly trade winds of the Northern Hemisphere collide head-on with the northeast trade winds coming from the Southern Hemisphere.

Due to intense solar heating near the equator, upon collision, the warm, moist air is forced up into the atmosphere, much like a hot air balloon. As the air rises, it cools, resulting in sudden showers and storms. As a side effect, because the air direction is primarily upward, little surface wind remains over the water in the ITCZ.

Sailors often refer to the area as “the calms” because the monotonous, windless weather can becalm sailing ships for weeks. In the “Age of Sail” (the period from approximately 1571-1862 during which international trade & warfare depended on wind power), to find oneself becalmed in the doldrums could mean death, since wind was the only effective way to propel ships across the ocean. Calm periods within the doldrums could strand ships for days or weeks, causing food and drinking water supplies to be exhausted. Even today, leisure and competitive sailors attempt to cross the zone as quickly as possible as the erratic weather and wind patterns may cause unexpected delays.