One problem we must face is that in the real world, and even in tropical rainforests where the extremes of winter cold and summer are absent, leaf color and shape change over time, as "wet" and "dry" seasons come and go. Tree phenology (study of a tree's response to seasonal and climatic changes) is a significant phenomenon even in tropics. Without information about appearance of the tree canopy at a given time, identification of tree species in tropics from aerial photographs may result in errors. A simple method to obtain phenological knowledge about a particular tree species is to take daily photographs during a complete seasonal/climatic cycle. These photographs illustrate tree phenology of one particular tree species near the INPA tower. Look specifically at the tree near the center of the image, and follow it during the period of one year. Four distinctly different appearances of the canopy can be seen.