Horse Latitudes

The horse latitudes are the subtropical high-pressure belts near 30 degrees north and south, where descending air in the poleward branch of the Hadley cell warms, dries, and suppresses cloud. Surface winds are light and variable, with frequent calms, clear skies, and low rainfall, which is why most of the world’s deserts and the major ocean subtropical gyres sit beneath them. Sailing vessels could stall here, the supposed origin of the name. The belts mark the divergence between the equatorward trade winds and the poleward mid-latitude westerlies, and they shift several degrees with the seasons.