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Two days before Hurricane Maria devastated Puerto Rico 

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a NASA satellite captured a 3-D view of the storm

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revealing the processes inside the hurricane that would fuel the storm’s intensification. 

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NASA’s precipitation satellite has an advanced radar 

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that measures both liquid and frozen water inside hurricanes. 

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This satellite is called the Global Precipitation Measurement Core Observatory, or GPM. 

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Now, for the first time, we can take you inside a hurricane in a 360-degree view of this data.

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You can look around by moving your device or clicking and dragging on the screen. 

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We’re currently inside Hurricane Maria when it was a Category 1 hurricane in September 2017.

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This was a few days before it rapidly intensified to a Category 5 hurricane.

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Look down and you'll see a map showing where we are inside Hurricane Maria 

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and what the colors are showing.

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The dots around you show areas of rainfall, 

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where green and yellow show low rates and red and purple show high rates.

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The colored areas below the dots show how much rain makes it to the surface.

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Look up and you’ll see blue and purple dots that show light and intense frozen precipitation.

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Right now we are traveling through a gap between rainbands.

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Now we’ll collapse the clouds of dots into the actual data values, 

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which are in millimeters of precipitation per hour.

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The rates in this storm vary from less than 0.5 millimeters per hour 

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to over 150 millimeters per hour.

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It’s these actual values that scientists use to figure out what’s going on inside hurricanes. 

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Next we’ll turn the numbers into a representation 

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that helps us to see other 3-D structures in the distance. 

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Wider, red and purple ellipsoids show higher rainfall rates 

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and spherical green and yellow ellipsoids show lower rainfall rates. 

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Rising to 5 kilometers, you’ll see a distinctive change to frozen precipitation, shown in blues and purples. 

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This transition is the melting layer where falling snow and ice 

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warm to the point that they melt into water drops.

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We are currently moving up a tall column of intense precipitation.

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Scientists call these hot towers. 

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Lots of heat and energy are released in hot towers 

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as rising water vapor condenses into precipitation.

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Most hot towers are between 10 and 15 kilometers high 

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- roughly the altitude that commercial jets fly. 

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Multiple hot towers are common in intensifying hurricanes. 

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Here’s another hot tower that’s about 17 kilometers tall.

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Hot towers often appear near the eyewall, 

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a ring of heavy wind and rainfall surrounding the center of the storm.

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We’re now in the eye of Hurricane Maria. 

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At this stage of development, Maria’s eyewall is asymmetrical 

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with heavier rain in the northern part colored in purple.

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This is common in storms impacted by environmental winds. 

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A few days after this time, Maria’s eyewall intensified and became more symmetrical.

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While NASA's GPM satellite can detect big features like the shape of the eyewall, 

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it can also measure tiny precipitation particles.

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These blue drops show the size and density of ice and water particles inside Hurricane Maria, 

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which is also known as the drop size distribution.

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Big drops are colored in dark blue and small drops in light blue and white.

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Looking at drop sizes and rainfall rates provides a key part of the equation

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in understanding hurricane intensity. 

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Factors such as temperature, humidity, wind speed, and clouds 

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influence the size of the precipitation particles, 

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which in turn affects how much rain falls and how a storm grows.

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These advanced satellite measurements are critical for improving forecasts 

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of how these powerful storms may intensify and where they may go.

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Scientists are seeing things never measured before, 

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revealing new insights into hurricanes -- drop by drop. 

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