The advent of satellite imagery opened our eyes to many unseen aspects of the airflow in the atmosphere which had been invisible to most scientific instruments. It gave us the possibility to trace the transportation of moisture from tropical regions to the higher latitudes. Further, we could integrate the amount of the water vapour throughout the depth of the troposphere (lowest layer of the Earth’s atmosphere) everywhere, especially over the oceans. The latter approach proved to be an invaluable tool to discover a weather phenomenon called “atmospheric river”.