GLOBE Cloud Watching: Ground Reports & Satellite Matches

Looking Up vs. Looking Down: Why NASA Needs Ground Observers

Whenever you look up at a cluster of puffy cumulus or wispy cirrus, you are seeing something orbiting satellites often struggle to fully capture. NASA has state-of-the-art instruments circling our planet—from Terra and Aqua to the new PACE mission—measuring solar radiation, aerosol layers, and cloud tops. But satellites only see clouds from above, looking down against the bright, reflective backdrop of land, snow, and oceans. They cannot see the cloud base, nor can they always resolve thin low-level stratus tucked underneath high cirrus layers.

That is where ground citizen scientists step in. Through the GLOBE Observer app, everyday observers record sky cover, cloud types, and surface conditions right from the ground. When your ground observation aligns with a satellite flyover, NASA can stitch together a complete top-to-bottom atmospheric cross-section. It is genuine, collaborative Earth science that anyone with a smartphone can join—no telescope or weather station required. ✨☁️

Timing the Flyover, Taking Photos & Reading Your Match Table

Participating is wonderfully straightforward once you master a couple of practical habits. First, while you can submit an observation anytime, the most scientifically valuable data happens within a 15-minute window of a documented satellite overpass. The app calculates exact overpass times for your location, giving you a friendly heads-up before Terra, Aqua, or geostationary satellites scan your sky.

Second, taking cardinal photos (North, South, East, West, up, and down) gives researchers visual ground truth to compare against radiometric readings. And the coolest part? A few days later, NASA sends you an automated satellite match email with a side-by-side comparison table showing your ground report alongside satellite imagery of that exact location. TuTu rounded up walkthroughs from NASA Goddard, Langley, and seasoned educators so you can set up your account, nail your overpass timing, and understand the observation workflow.