Hurricanes cool ocean temperatures by absorbing energy from the water and by churning up colder water from below. There is no better way to show this process than by looking at the sea surface temperature after a storm. In this case, the image shown here compares the satellite sea surface temperature data from September 12, 2011 to the average for that day over the 1971-2000 time period. The signatures of Hurricane Katia and Tropical Storm Nate are clearly visible as areas of colder than normal water in areas that are otherwise warmer than average. Similar features can also be seen in the actual sea surface temperature data from the same day.