Tropical rainfall comprises more than two-thirds of global rainfall.
It is the primary distributor of heat through the circulation of the atmosphere. Understanding rainfall and its variability is crucial to understanding and predicting global climate change. Our current knowledge of rainfall is poor, especially over the oceans. These new measurements will increase our knowledge of how rainfall releases heat energy to drive atmospheric circulation. TRMM's orbit will range between 35 degrees north and 35 degrees south of the equator, allowing TRMM to fly over each position on the Earth's surface at a different local time each day.