For each 1,000 foot rise in altitude there is a 4°F drop in temperature. For example, if at sea level the average temperature is 75°F, at 10,000 feet the average temperature would be only 35°F. This has a dramatic effect on plant and animal distribution.

In tropical mountainous areas several types of forests occur. Montane forests are cooler and may contain deciduous trees. At sea level, there are lowland rainforests and mangroves. At cloud level, moist, dripping cloud forests may occur. They are cooler than lowland forests. High mountains may also have alpine, tundra, and snow covered peaks.