In the doldrums

What meteorologists call the Intertropical Convergence Zone is known to sailors as the Doldrums.

The trade winds from the southern hemisphere and the northern hemisphere meet near the equator. The winds converge and, for most of the time, produce upward air currents that cancel out the surface winds. Pockets of low-pressure air form that often create hot, humid and very still conditions.

These equatorial conditions became known as the Doldrums by the sailors who travelled through them. The sailing boats, without winds, could become becalmed for weeks at a time.

Samuel Taylor Coleridge described being becalmed in his Rhyme of the Ancient Mariner:

Day after day, day after day,

We stuck, nor breath nor motion;

As idle as a painted ship

Upon a painted ocean.

This is what Eric Hiscock said in Voyaging Under Sail (1966) about sailing through the Doldrums:

… an experience which every sailor-man ought to have once in his lifetime … But once is enough, and if I ever have to pass through that area of calms, squalls, heat, and rain again, I hope to have an engine of useful power and a plentiful supply of fuel for it.

The sailors of the time before engines found these long periods of inactivity at first monotonous and then despairing. Frustration built up as the water and food started to run out. Hence, the Doldrums gave its name to periods of stagnation and depression.

According to the Oxford English Dictionary the first recorded use of Doldrums is in 1811 with an origin from Old English dol meaning dull or foolish. This may have been preserved in a local English dialect spoken by some of the sailors. The OED also suggests that the ending is perhaps based on tantrum (first recorded 1748), which describes a fit of passionate bad temper. It is more likely to have been based on humdrum (first recorded use in 1553), an older word that describes a sense of monotony and dullness.