Sentence:  The north boundary of Zone A is a belt of high barometric pressure known to many generations of seafaring men as the "<WSD>Horse Latitudes</WSD>." Here air currents are divergent and there is relatively low humidity. 
Meaning of the word marked with <WSD> tags:  The warm, subtropical bands which encircle the globe between approximately 30 and 35 degrees both north and south of the Equator, characterized by high atmospheric pressure and dry variable winds ranging from calm to light.