We can download data as a single snapshot in a single file, but oftentimes that data is generated piece-by-piece. In the map above, NASA shows how they piece together rain data with a network of satellites:
The ten currently-flying satellites in the Global Precipitation Measurement Constellation provide unprecedented information about the rain and snow across the entire Earth. This visualization shows the constellation in action, taking precipitation measurements underneath the satellite orbits. As time progresses and the Earth’s surface is covered with measurements, the structure of the Earth’s preciptation becomes clearer, from the constant rainfall patterns along the Equator to the storm fronts in the mid-latitudes.