Rainfall variation in the tropics also can affect the weather in locations thousands of miles away, influencing the lives and livelihoods of populations worldwide. NASA's Goddard Space Flight Center in Greenbelt, Md., fabricated the observatory's structure and support systems, integrated and tested the spacecraft, provided two science instruments and operates the TRMM satellite via NASA's Tracking and Data Relay Satellite System. TRMM is part of NASA's Earth Science Strategic Enterprise, a long-term research program designed to study the Earth's land, oceans, air, ice and life as a total system. Satellite has a collection of instruments designed to remotely sense rainfall in tropical regions of the globe. One unique aspect of TRMM is that it carries the first spaceborne weather radar.
Weather radar transmits microwaves and then measures the waves reflected back to it.
This is called backscatter. It is the backscatter energy that is converted into radar reflectivity values and rainfall rates useful to scientists and the public. Meteorologists call these hydrometeors. Hydrometeors vary in size and shape due to the conditions within the clouds such a, temperature and convective motions. Lay out a piece of waxed paper the length of a table or desk.