A swirling mass of air sweeps a cloud of dust into the Mediterranean Sea in this image acquired on December 14, 2005. The brown and tan colors in this image represent the sand dunes and stone plateaus of the Sahara in North Africa. The country at the left of the image is Algeria; to its right is the country of Tunisia. The far right side of the image is the country of Libya. At the top of the image, just across the Mediterranean, are (from left to right) portions of Sardinia, Sicily, Italy, and Greece. The Sahara, which means “desert” in Arabic, is the world’s second largest desert (after Antarctica) spanning 9 million square kilometers (3.5 million square miles). The Sahara is of course very hot and dry, with a mean annual temperature of about 30 degrees Celsius (86 degrees Fahrenheit) and mean annual rainfall of 25 millimeters (less than an inch). But what makes this such a challenging environment for both people and wildlife is the extreme variability of climate: both have to adapt to extreme hot and cold, as well as prolonged droughts followed by massive storm events. Dust storms of this sort are a significant natural hazard, posing dangers to navigation and causing respiratory distress. Images like this one can be used to track the movement of storms as well as serve as an early warning system, alerting local and region officials of impending storms and allowing for improved preparation and response.