A Dry Rainforest?
In class I learned to classify a rainforest as a forest that receives ample precipitation throughout the year. I was confused then to find out that the Carara National Forest, while still a vibrant green, is currently in its dry season. We learned that there are different formations, or classifications, of rainforests that depend on factors including climate, soil, and elevation. Carara, for example, is a seasonal forest because it experiences a wet and dry season.
The seasonal changes in Carara are not due to Earth’s axial tilt, like the seasons we are used to in temperate climates. Instead, the seasons are a result of wind patterns over the mountainous continental divide. During the summer strong trade winds drive clouds from the Caribbean side of Costa Rica over the continental divide to the Pacific side. On their journey up the mountains the clouds lose much of their precipitation and create a rain shadow effect in Pacific forests like Carara. In the winter, the trade winds die down and allow clouds from the Pacific side to rise up over the central mountains, thus beginning the wet season.