Tree ferns in a cloud forest on Mount Kinabalu, Borneo

One of the hanging bridges of the sky walk at the Monteverde Cloud Forest Reserve in Costa Rica

A cloud forest or fog forest is a tropical or subtropical, contains mostly evergreen trees, and is high up on a mountain. There is a large amount of water in the air. Cloud forests have cloud cover for much of the year, usually at the same height as the canopy, the place where the trees' branches meet.