The presence of very dry materials is the main factor that leads to extreme fire behavior and growth at night, as found in a new Canadian study.

A version of this essay appeared in The New York Times Book Review. A cloud is a spell against indifference, an emblem of the water cycle that makes this planet a living world capable of trees and tenderness, a great cosmic gasp at the improbability that such a world exists, that across the cold expanse of spacetime strewn with billions upon billions of other star systems, there is nothing like it as far as we yet know. Clouds are almost as old as this world, born when primordial volcanos first exhaled the chemistry of the molten planet into the sky,… read article

Two new studies document rare cases in which people who rinsed sinuses with unsterilized tap got infected with brain-eating amoebas.

Following the removal of invasive goats, giant tortoises are once again thriving in the Galápagos islands.

Less than half of more than 400 mammal species studied have males that are, on average, heavier than females, challenging a long-held assumption.

Iloprost has been proven to prevent the amputation of frozen fingers and toes. It is now authorized for treating severe frostbite in the U.S.