PASSIVE REMOTE SENSING
Passive remote sensing refers to the sensing of electromagnetic waves that did not originate from the satellite or instrument itself. The sensor is merely a passive observer collecting electromagnetic radiation. Passive remote sensing instruments onboard satellites have revolutionized weather forecasting by providing a global view of weather patterns and surface temperatures. A microwave imager onboard NASA's Tropical Rainfall Measuring Mission (TRMM) can capture data from underneath storm clouds to reveal the underlying rain structure.