... the broad belt around the earth known as the trop-ics the region 23 1⁄2° north and south of the equator— the weather is much different from that of the middlelatitudes. In the tropics, the ... stable atmosphere tends to spread horizontally, rather than mix vertically. The stability of the atmosphere is determined by the way the air temperature changes with height (the lapse rate). When the ... spell. The winds in the tropics generally blow from the east, northeast, or southeast the trade winds. Because the variation of sea-level pressure is normally quitesmall, drawing isobars on a weather...