Climates around the world are classified according to the Köppen Climate Classification System. The classifications in this system are based on temperature and precipitation averages on a monthly and yearly basis. One of the classifications is that of tropical wet climates, or rainforests. Humid tropical climates have distinguishing characteristics other than temperature and precipitation. Tropical humid climates have distinct locations and abundant animal and plant life.
Rainforests are warm with temperatures staying around 80 degrees Fahrenheit year-round and fluctuating little during any given month or year. More fluctuation occurs in daily temperature than in monthly or yearly temperature. Areas with a humid tropical never experience frost.
The high year-round temperatures cause intense heating of the surface of the earth. This heating results in the formation of cumulus and cumulonimbus clouds every day, usually in the afternoon. The clouds generate almost daily thunderstorm activity. Rainforests receive approximately 103 inches of rainfall a year, with rain falling all year. Humidity hovers between 77 and 88 percent every day.
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Latitude is a determining factor in the existence of tropical climates. All humid tropical climates are near the equator between the Tropic of Cancer and the Tropic of Capricorn or latitudes that range between 10 degrees south to 25 degrees north. For example, rainforests are in the Amazon Basin, the Congo Basin of equatorial Africa and parts of the East Indies.
The humid tropical climate features thick vegetation that grows in two layers. The canopy, or top layer, contains trees that grow to staggering heights, as high as 250 feet or more. Thick vines grow into the canopy. The next layer comprises smaller trees, vines, palms, orchids and ferns. Little sunlight reaches this layer because of the dense canopy overhead, so only plants that can tolerate low light grow in this layer. Many houseplants come from this layer. They are able to thrive in homes because, like the rainforest, a home provides the plants with the reduced light levels to which they are accustomed. The floor of the rainforest has few plants because the vegetation above it blocks most sunlight. Rainforests make up one of the most diverse plant ecosystems on the planet and scientists continue to find new plant life.
Rainforests are home to almost half of the animals inhabiting the globe. Scientists estimate that many species of animals residing within the areas of humid tropical climate have not yet been identified. Several factors allow for the diversity and large number of animals found in this type of climate. Many rainforests are old -- scientists believe one in Asia is more than 100 million years old -- so animals have had a long time to evolve. The climate also fosters animal life. Year-round warm temperatures and abundant food and water make it easier for animals to survive and flourish. Some animals that live in the rainforest include tarantulas, jaguars, gorillas, toucans, parrots and okapis.