Philip Kennicott visited New Gourna and Cairo in Egypt and Diyarbakir in Turkey to explore historic cooling techniques. Sima Diab photographed them in Egypt. Dec. 28 at 6:30 a.m.

Winter is by far the most popular time to visit Egypt's capital because the days are warm and sunny and the evenings are cool and breezy. If you're planning a trip between December and February ...