Tropical Savannah (Tropical Wet and Dry) climate is characterized by a distinct alternation of a wet season (when the ITCZ moves overhead bringing rainfall) and a dry season (when the ITCZ moves away). This is the defining characteristic — a definite dry season and a definite wet/rainy season. The dry season can be quite prolonged (3-8 months). This contrasts with the Tropical Rainforest climate which has rainfall throughout the year.