Horse latitudes

Seamen were paid partly in advance before a long voyage, and they frequently spent their pay all at once, resulting in a period of time without income.

Ships often became becalmed in mid-ocean in this latitude, thus severely prolonging the voyage; the resulting water shortages made it impossible for the crew to keep the horses alive, and they would throw the dead or dying animals overboard.

[3] A third explanation, which simultaneously explains both the northern and southern horse latitudes and does not depend on the length of the voyage or the port of departure, is based on maritime terminology: a ship was said to be 'horsed' when, although there was insufficient wind for sail, the vessel could make good progress by latching on to a strong current.

Furthermore, The India Directory in its entry for Fernando de Noronha, an island off the coast of Brazil, mentions it had been visited frequently by ships "occasioned by the currents having horsed them to the westward".

[5] A further explanation is that this naming first appeared in the English translation of a German book [example needed] where Rossbreiten was incorrectly understood as Pferdbreiten.

[citation needed] The heating of the earth at the thermal equator leads to large amounts of convection along the Intertropical Convergence Zone.

The equatorward migration of the subtropical ridge during the cold season is due to increasing north-south temperature differences between the poles and tropics.

[9] The latitudinal movement of the subtropical ridge is strongly correlated with the progression of the monsoon trough or Intertropical Convergence Zone.

The subtropical ridge across North America typically migrates far enough northward to begin monsoon conditions across the Desert Southwest from July to September.

[15] In summer, On the subtropical ridge's western edge (generally on the eastern coast of continents), the high-pressure cell pushes poleward a southerly flow (northerly in the southern hemisphere) of tropical air.