What factor distinguishes wet tropical climate from dry climate?

The primary factor that distinguishes wet tropical climates from dry climates is the amount of precipitation received throughout the year. Wet tropical climates experience high levels of rainfall, typically exceeding 60 inches (1,500 mm) annually, and maintain high humidity and warm temperatures. In contrast, dry climates receive significantly less precipitation, often less than 20 inches (500 mm) annually, and can have extreme temperature variations. This difference in moisture availability primarily shapes the vegetation and ecosystems found in these regions.