Go ad-free with Premium

Topic: heating and cooling systems

In this July 8, 2016 photo, icicles hang from the roof of an adobe home in San Antonio de Putina in the Puno region of Peru, where farmers raise alpacas and sheep for their wool. Every winter freeze destroys the tough grasslands the animals feed on and almost no crops can survive in the nutrient-poor soil. (AP Photo/Rodrigo Abd) (AP)

Ask Umbra