On September 5, 2017 at 1 p.m. EDT (1700 UTC) the radar on the Global Precipitation Measuring Mission (GPM) satellite captured a 3-D view of the heat engine inside of category-5 Hurricane Irma. Under the central ring of clouds that circles the eye, water that had evaporated from the ocean surface condenses, releases heat, and powers the circling winds of the hurricane. The radar on the GPM satellite is able to estimate how much water is falling as precipitation inside of the hurricane, which serves as a guide to how much energy is being released inside the hurricane's central "heat engine."