Rainforests are clustered around the equator (Central and South America, Africa, South Asia and Australia) and occur on the 7% of the dry land surface of the planet where it is both warm enough and wet enough. There are temperate rainforests such as in the Olympic peninsula, but without tropical temperatures they have much lower biological diversity. Rainforests require a minimum of 100 inches of rain a year. They normally have dry seasons but require moisture even in the drier months. In contrast, a New England forest receives about 40 inches of rain a year and the Arizona desert 7 inches.

Rain forest tress are about 100 feet tall, but there are taller trees known as “emergents” that can easily reach an additional 30 feet above the canopy. The forest is also very stratified with different animals and plants living at different levels. Virtually the only species the canopy and the rainforest floor share in common are the trees themselves. The birds of the rainforest canopy are a completely different set of species from those at lower levels. The canopy is in brilliant sunlight during the day, but it is dark (almost gloomy) at the rain forest floor, where only one to two percent of light reaches.