A Bit Of Tropical Meteorology

摘要

In the low-latitude atmosphere, air mass properties are quite uniform B across hundreds, if not thousands, of miles. Over tropical oceans, the air mass is very warm and humid. Land areas tend to be hotter, yet high humidity also prevails, particularly when rain forest is the predominant vegetation. Cool and dry air masses from the far north seldom if ever invade; their province is the mid latitude zone of westerly winds, and the polar regions. But over the tropical Atlantic, the influence of Africa's great desert, the Sahara, is sometimes experienced far downstream. The Sahara is subtropical, but a massive arid landmass. And occasional bursts of winds sweeping westward off the northern continent export gigantic clouds of dust, and low-level dry air. The hot, dry, dusty layer can dip into low latitudes on its journey toward the Americas, a voyage that takes about ten days, within the trade wind flow.