On December 10, I posted a blog about the Khamseen winds, the hot winds that choke the Eastern Mediterranean during the spring, but then summer brings the Etesian winds to the region.
In THE DEADLIEST LIE, Miriam mentions how the Etesian winds cool their home and the entire city:
“The cool breath of the Etesian winds billow and snap the purple, tied-back drapes that skirt the floor and separate Papa’s study from the peristyle. The arrangement of our cobblestone streets takes full advantage of these salubrious northwesterly winds. Originating in the Aegean, they whisper across the Mediterranean to temper our summer sun.”
In the summer, the air above the North African desert becomes hot. As the air heats, it expands, becomes lighter, and rises. The air above the Mediterranean Sea stays cooler than the air above the desert. Because the cooler air is heavier, it stays close to the ground. The cool air flows south to replace the hot air rising from the desert, and this flow of air toward the desert causes the Etesians.
By harnessing the power of these gentler winds, the Egyptians could carry on a two-way trade along the Nile. Whereas the river current carried boats northward (downstream) toward the Mediterranean, the Etesian winds pushed sailboats southward (upstream) toward the interior of Africa. Thus they could move goods against the current.