These infrared, microwave, and visible images were created with data retrieved by the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite.
From the National Weather Service:
HURRICANE BILL INTERMEDIATE ADVISORY NUMBER 21A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
200 PM AST THU AUG 20 2009
...LARGE HURRICANE BILL RACING NORTHWESTWARD...SPREADING HIGH SWELLS OVER THE WESTERN ATLANTIC...
AT 200 PM AST...1800 UTC...THE EYE OF HURRICANE BILL WAS LOCATED NEAR LATITUDE 23.2 NORTH...LONGITUDE 62.6 WEST OR ABOUT 645 MILES...1035 KM SOUTH OF BERMUDA.
BILL IS MOVING TOWARD THE NORTHWEST NEAR 18 MPH...30 KM/HR...AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE TROUGH FRIDAY. ON THIS FORECAST TRACK...THE CORE OF HURRICANE BILL IS EXPECTED TO PASS OVER THE OPEN WATERS BETWEEN BERMUDA AND THE EAST COAST OF THE UNITED STATES EARLY SATURDAY.
MAXIMUM SUSTAINED WINDS REMAIN NEAR 120 MPH...195 KM/HR...WITH HIGHER GUSTS. BILL IS A CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON SCALE. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS AND BILL COULD REGAIN CATEGORY FOUR STATUS ON FRIDAY.
BILL IS A LARGE TROPICAL CYCLONE. HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 105 MILES...165 KM...FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 260 MILES...415 KM.
THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY AN AIR FORCE RESERVE HURRICANE HUNTER PLANE WAS 951 MB...28.08 INCHES.
Because infrared radiation does not penetrate through clouds, AIRS infrared images show either the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the storm. In cloud-free areas the AIRS instrument will receive the infrared radiation from the surface of the Earth, resulting in the warmest temperatures (orange/red).
In the AIRS microwave imagery, deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. On the other hand, land appears much warmer due to its high radiation emissivity.