NASA's Atmospheric Infrared Sounder (AIRS) was monitoring Tropical Storm Hanna as it took aim at southern Texas on July 26. Perched on NASA's Aqua satellite, AIRS is an instrument that studies Earth's weather and climate.

Hanna made landfall as a Category 1 hurricane around 5 p.m. local time over Padre Island, Texas, on July 25. Since then, the storm has lost steam, weakening to a tropical storm in the early morning hours of July 26, and then to a tropical depression by the afternoon. The purple areas in the AIRS image — taken at 1:35 a.m. local time on July 26 — show regions within the tropical storm with cold clouds high in Earth's atmosphere that tend to produce heavy rainfall. The National Hurricane Center predicts that Hanna will continue over northeastern Mexico, where it will dissipate by late in the day on July 27.

AIRS, in conjunction with the Advanced Microwave Sounding Unit (AMSU), senses emitted infrared and microwave radiation from Earth to provide a three-dimensional look at Earth's weather and climate. Working in tandem, the two instruments make simultaneous observations down to Earth's surface. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, three-dimensional map of atmospheric temperature and humidity, cloud amounts and heights, greenhouse gas concentrations and many other atmospheric phenomena. Launched into Earth orbit in 2002, the AIRS and AMSU instruments fly aboard NASA's Aqua spacecraft and are managed by NASA's Jet Propulsion Laboratory in Southern California, under contract to NASA. JPL is a division of Caltech.

More information about AIRS can be found at https://airs.jpl.nasa.gov.