In late January and early February 2026, surges of Arctic air funneled into eastern North America, causing cold and wintry conditions across much of the United States. Snow and ice blanketed large swaths of the country, stretching as far south as Georgia, in a layer of white. Meanwhile, waters off the west coast of Florida lit up in brilliant shades of blue.
In this rare outbreak of intense winter weather, cold air infiltrated Florida and drove temperatures below freezing in several counties at the start of February. This frigid intrusion not only caused beautiful phenomena in the atmosphere, forming cloud streets, but it also produced a colorful display in the shallow marine waters below, stirring up carbonate sediment from the seafloor.
On February 3, the MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA’s Terra satellite captured this image (right) of brightened waters over the West Florida Shelf, a broad and shallow continental shelf region known as a carbonate ramp. The blue color comes from suspended calcium carbonate (CaCO3) mud, which consists primarily of remnants of marine organisms that live on the shelf. For comparison, the left image shows the area on January 24, before the cold air arrived.
The mud was mostly kicked up by wind-stirred ocean waters during the cold air event, said James Acker, a data support scientist at the NASA Goddard Earth Sciences Data and Information Services Center. Sediment suspension events like this are more typically associated with hurricane winds that churn the water, as with Melissa in 2025, but the winds brought by strong cold fronts can have a similar, if less dramatic, effect.
“Another interesting aspect of these events is that the cold air cools off the shallow water on the banks and makes it denser than the surrounding warmer open ocean water,” Acker said. When this dense water sin …