#evaporation

"Hydroclimate" - Acrylic paint on canvas

Cooling with clay: Terracotta evaporative systems benefit both ancient and modern civilizations

June 21 marked the first day of summer in the Northern Hemisphere, and meteorologists are forecasting that temperatures will only climb up from here. People globally will need ways to stay cool in the coming months, and in certain cases, terracotta structures may be an affordable, eco-friendly solution to this need. Terracotta, Italian for “baked earth,” is a type of earthenware pottery that fires to a distinct reddish-brown color. It has been around for thousands of years, serving in various applications spanning architecture, art, and functional household items. Like other earthenware, terracotta is highly porous due to being fired at lower temperatures. This property allows it to be used as a conduit for evaporative cooling.

Water cycle.

Naturlehre für die Volksschulen. 1948.

Clouds refueling

It's the most fundamental of processes—the evaporation of water from the surfaces of oceans and lakes, the burning off of fog in the morning sun, and the drying of briny ponds that leaves solid salt behind. Evaporation is all around us, and humans have been observing it and making use of it for as long as we have existed. And yet, it turns out, we've been missing a major part of the picture all along. In a series of painstakingly precise experiments, a team of researchers at MIT has demonstrated that heat isn't alone in causing water to evaporate. Light, striking the water's surface where air and water meet, can break water molecules away and float them into the air, causing evaporation in the absence of any source of heat. The astonishing new discovery could have a wide range of significant implications. It could help explain mysterious measurements over the years of how sunlight affects clouds, and therefore affect calculations of the effects of climate change on cloud cover and precipitation. It could also lead to new ways of designing industrial processes such as solar-powered desalination or drying of materials.